TRCI-2009Publisher BCI Basle Chemical Industry Edition: 2009
replaces: Edition 2001
TRCI Page 2 of 70
TRCI Edition 2009 Tank Farm Guidelines for the Chemical
Industry
Preface to the 2009 The TRCI Guidelines of 2001 had to be reviewed
since the VWF (Ordinance for the Protection of Water from
Potentially Water-Polluting Liquids) was withdrawn. Instead of the
VWF, two enforcement regulations of the KVU (Conference of the
Heads of Environmental Protection Offices in Switzerland) are now
applicable. The review also updates the entire document and
restructures it. The TRCI Guidelines are applicable to storage
facilities and plant tank farms in the chemical and pharmaceutical
industry. They are applicable to liquid chemicals and can also be
used for plant facilities in an analogous manner. They are listed
as Engineering Rules by the Swiss Federal Office for the
Environment (BAFU). The guidelines are obligatory for the design of
storage facilities in the BCI, they serve as a supplement to the
provisions and directives of the authorities. A team of experts
from CIBA, CLARIANT, HOFFMANN-LA ROCHE, HUNTSMAN and LONZA reviewed
the TRCI Guidelines for the BCI. All rights reserved © Copyright
2009 by BCI/TRCI The TRCI Guidelines are available in German,
French and English via: http://www.bafu.admin.ch/tankanlagen
TRCI Edition 2009
1.2 Purpose and scope of
application....................................................................................
6
1.3 Conditions for the operation of tank farms according to TRCI
...................................... 6
1.4 Water pollution control areas, ground water pollution control
zones and water pollution control measures
.......................................................................................................................
7
1.5 Classification of liquid chemicals
...................................................................................
7 1.5.1 Water pollution
control..........................................................................................
7 1.5.2 Fire
protection........................................................................................................
7 1.5.3 Air pollution control
..............................................................................................
8
2.1 General
comments...........................................................................................................
9 2.1.1 Site selection and assessment of construction
site................................................. 9 2.1.2
Planned arrangement
.............................................................................................
9 2.1.3 Tanks in underground concrete spaces
................................................................ 11
2.1.4 Filling points and drum filling points
..................................................................
11
2.2 Tank and protective
clearance.......................................................................................
12 2.2.1 Outdoor storage tanks and drum storage
............................................................. 12
2.2.2. Storage tanks in
buildings....................................................................................
15 2.2.3 Outdoor filling points and drum filling
points.....................................................
16
3 Protective structures,
foundations..........................................................17
3.3
Foundations...................................................................................................................
20
TRCI CONTENTS Page 4 of 70
TRCI Edition 2009 Tank Farm Guidelines for the Chemical
Industry
4 Storage tanks and equipment
.................................................................21
4.1 Storage tanks
.................................................................................................................
21 4.1.1 General comments, terms
....................................................................................
21 4.1.2 Storage tanks of metal
.........................................................................................
22 4.1.3 Storage tanks of plastics
......................................................................................
23 4.1.4 Heating and cooling systems
...............................................................................
23 4.1.5 Inert gas blanketing
.............................................................................................
23 4.1.6 Tank surface
coating............................................................................................
24 4.1.7 Thermal
insulation...............................................................................................
25
4.2 Piping
............................................................................................................................
26 4.2.1 General comments, terms
....................................................................................
26 4.2.2 Requirements of piping
.......................................................................................
26 4.2.3 Design, installation
..............................................................................................
26 4.2.4 Connection of pipes to tanks and tankers
............................................................ 27
4.2.5 Hoses
...................................................................................................................
27 4.2.6 Gas balance, pressure compensation
lines........................................................... 27
4.2.7 Overspill, overflow equipment
............................................................................
28 4.2.8 Distributing and return lines
................................................................................
28 4.2.9 Testing of
piping..................................................................................................
28 4.2.10 Pipe insulation
.....................................................................................................
28
4.3 Valves and fittings
........................................................................................................
29 4.3.1 General comments
...............................................................................................
29 4.3.2 Shutoff valves
......................................................................................................
29 4.3.3 Vent valves
..........................................................................................................
29 4.3.4 Flame
arresters.....................................................................................................
29
4.4
Pumps............................................................................................................................
31
5 Ecology, safety and fire protection
.........................................................34
5.1 Displacement and breathing losses
...............................................................................
34 5.1.1 Displacement
losses.............................................................................................
34 5.1.2 Breathing losses
...................................................................................................
34 5.1.3 Measures to prevent or reduce emissions
............................................................
35
5.2 Liquid losses
.................................................................................................................
36
5.4 Fire and explosion
protection........................................................................................
38
TRCI Edition 2009 Tank Farm Guidelines for the Chemical
Industry
5.4.1 General comments
...............................................................................................
38 5.4.2 Definition,
terms..................................................................................................
38 5.4.3 Alarms
.................................................................................................................
39 5.4.4 Outdoor fire protection measures
........................................................................
39 5.4.5 Protective measures in buildings
.........................................................................
42 5.4.6 Protective measures in electrical rooms
..............................................................
42
5.5 Earthquake safety
..........................................................................................................
43
6.2 Obligations of the sponsorship or construction management
....................................... 44
6.3 Operating permit
...........................................................................................................
44
6.6 Existing facilities and facility
parts...............................................................................
47
7.1 Minimum dimension of sealed pavings at transfer sites
............................................... 49
7.2 Air pollution control (limit values)
...............................................................................
51
7.3 Test procedures for facility parts
..................................................................................
52
7.4 Leakage testing of protective
structures........................................................................
53
7.6 Precautions against the hazardous effects of electric current
....................................... 55
7.7 Protection indices (to determine min. fire protection measures)
.................................. 56
7.8 Calculation of the required quantity of cooling water
.................................................. 57
7.9 Tank farm design
terms.................................................................................................
65
7.11 Abbreviations
................................................................................................................
69 7.11.1 Abbreviations for authorities, regulations, specialist
agencies, etc. .................... 69 7.11.2 Technical
abbreviations.......................................................................................
70 7.11.3 Material
abbreviation...........................................................................................
70
TRCI Edition 2009 Tank Farm Guidelines for the Chemical
Industry
1 General information 1.1 Introduction The TRCI are to be applied
to the construction and operation of facilities for the storage and
transfer operations of liquid chemicals. They take into account the
specific requirements of the chemical industry and are mainly based
on - the federal law governing environmental protection
(Environmental Protection Act [USG])
[3]; - the Swiss Water Protection Act (GSchG) [1] and pertaining
regulations; - Ordinance for the protection against accidents
(Accident Ordinance, StFV) [7]; - Enforcement regulations and
guidelines of the KVU [34 and 35]; - Clean Air Ordinance (LRV) [5];
- SUVA Bulletin 2153, Explosion Protection: Principles, minimum
provisions, zones [16].
The TRCI only takes into account regulations, which are valid
throughout Switzerland. Depending on the location of the
facilities, any special Cantonal or local regulations are also to
be taken into account. Any deviation must be agreed during the plan
approval procedure. The Engineering Rules are to be adhered to on
principle (KVU [34-05]). Chapter 7.10 contains a summary of the
basic documents.
1.2 Purpose and scope of application The TRCI are applicable to
storage facilities and plant tank farms of the chemical and
pharmaceutical industry. They take into account facilities used for
storing and transfer of liquid chemicals (tanks and drums with a
usable volume above 20l). They only ensure adequate safety when
they are applied in their entirety and serve, in particular - the
protection of watercourses - fire protection - air pollution
control - labour protection (personal protection)
The TRCI may also be applied to plant facilities in an analogous
manner. The TRCI do not cover the following items - Storage and
transfer of liquid fuels (see CARBURA guidelines [8]; - Liquified
gases (SUVA [16]) 1.3 Conditions for the operation of tank farms
according to TRCI Location: Tank farms are to be installed within
an enclosed and supervised area. Tank farms for
flammable liquids may only be installed in an area for which a fire
brigade trained to deal with chemical hazards is responsible;
Operation: The operation of storage facilities must be registered
or approved, on principle (see Chap. 6);
Safety: Tank farms are to be equipped with safety devices according
to Chap. 5; Maintenance and Inspection: Tank farms must be
maintained and inspected according to Chap. 6; Register: The
operator has to keep a register on storage facilities with
potentially water-
polluting liquids.
TRCI Edition 2009 Tank Farm Guidelines for the Chemical
Industry
1.4 Water pollution control areas, ground water pollution control
zones and water pollution control measures
Switzerland is divided into water pollution control areas, ground
water pollution control zones and ground water pollution control
sites with regard to water pollution control measures to be applied
(see GSchV Art. 29 and 31 [2]). The principles of handling
potentially water-polluting liquids are stated in the Water
Protection Act (Art. 22 ff. GSchG [1]) and provisions concerning
facilities with potentially water-polluting liquids in particularly
endangered water pollution control areas are contained in the GSchV
(Art. 32 and 32a as well as Appendix 4, Items 21, 22 and 23). Water
pollution control measures outside of ground water pollution
control zones and sites (see also KVU [35-1.1]): These include -
Prevention of liquid losses; and, depending on the storage facility
and the transfer point, - the easy detection of liquid losses or -
the easy detection and retention of leaking liquids are demanded.
Water pollution control measures in ground water pollution control
zones and sites: In relation to the pollution control measures
stated above, respective pollution control measures are to be
implemented for facilities permitted in ground water pollution
control zones and sites which ensure that liquid losses are easily
detected and leaking liquids are completely retained. Industrial
and commercial operations emanating a danger for ground water are
not permitted (see GSchV Art. 29 and 31 [2]). 1.5 Classification of
liquid chemicals All liquid chemicals are classified according to
the aspects listed below.
1.5.1 Water pollution control Furthermore, the GSchV differentiates
between liquids which can pollute water in small quantities and
other potentially water-polluting liquids. Correspondingly, the
potentially water-polluting liquids are divided into two classes in
relation to their properties according to KVU [35-4]: - Class A: if
they can change water adversely in small quantities; - Class B: if
they can change water adversely in large quantities.
In mixed storage, the measures are in line with liquids of Class A.
A list of classified liquids issued by BUWAL (now BAFU) [4] is to
be observed. Class 1 of the 1999 list corresponds to Class A today
and Class 2 to Class B. 1.5.2 Fire protection The classification of
liquids for fire protection purposes is based on the degree the
fire hazard as represented by the flash point (according to VKF
[Association of Cantonal Fire Insurance Companies], Fire Protection
Guidelines, Flammable Liquids [9]). Flammable liquids are allocated
to the following hazard classes according to their fire and
explosion properties (EN classification see also allocation table
[9]).
TRCI 1 General information Page 8 of 70
TRCI Edition 2009 Tank Farm Guidelines for the Chemical
Industry
F1 = Liquids with a flash point below 21°C
F2 = Liquids with a flash point of 21 to 55°C
F3 = Liquids with a flash point above 55 to 100°C
F4 = Liquids with a flash point above 100°C
F5 = Liquids, not easily inflammable
F6 = Liquids non-flammable
1.5.3 Air pollution control The maximum permitted concentrations
stated in the Clean Air Ordinance (LRV [5]) must be complied with
for tanks venting into the air (Chap. 7.2). Further requirements by
Cantonal authorities are to be observed. For information on tank
breathing losses, see Chap. 5.1. 1.6 Tank farms and transfer sites,
definition 1.6.1 Tank farms Storage facilities with a usable volume
above 450 l must be registered or approved (KVU [34- 01]).
Installation A distinction is made between - Facilities
outdoors,
· Free-standing or · Non-free-standing (buried)
- Facilities in underground concrete spaces and buildings ·
Free-standing or · Non-free-standing (buried)
Free-standing refers to storage tanks and pipelines the external
walls of which are visible to such an extent that liquid losses can
be easily detected from outside; storage tanks are also free-
standing if their bottom cannot be seen from the outside but they
are permanently monitored by a leak detection system for liquid
losses. All other storage tanks and pipelines are considered
buried. 1.6.2 Drum storage Drum storage refers to storing
potentially water-polluting liquid chemicals in drums. Drums refers
to vessel from 20 l up to a usable volume of 450 l. 1.6.3 Transfer
sites Filling stations and drum filling systems are considered to
be transfer sites. - Filling stations: Transfer between transport
vessels or between transport vessels and
vessels of storage and plant facilities; - Drum filling systems:
Transfer from storage or transport vessels to drums.
TRCI 2 Planning and design of tank farms Page 9 of 70
TRCI Edition 2009 Tank Farm Guidelines for the Chemical
Industry
2 Planning and design of tank farms 2.1 General comments 2.1.1 Site
selection and assessment of construction site Important site
selection aspects for a new plant or the extension of an existing
one: - Local conditions: Ground water pollution control zone
including ground water pollution
control site, water pollution control area (Chap. 1.4), building
zone (according to town planning), transport links (railway, road),
availability of firefighting water and containment basin, utility
connections (power, nitrogen for blanketing, compressed air for
instrumentation and controls, steam for heating purposes, cooling
media, etc.), building ground, sewer connection, exhaust air
treatment, existing pollution by immission;
- Classification of liquid chemicals according to their
water-polluting properties and according to their fire hazard
ratings (Chap. 1.5);
- Liquid chemicals requiring, due to their hazard class, special
safety measures; - Obligation to approve, register and control
facilities with potentially water-polluting liquids
of Class A (KVU [34-01] and [34-01-1]), see also Chap. 6.1:
Medium-sized tank farms (with tanks from 2 up to 250m3) in Water
Pollution Control
Areas A ; Large tank farms (with tanks starting 250m3) in Water
Pollution Control Areas A only with
exceptional approval and in Area Z only with approval; - Impact of
the facility on the neighbourhood:
Possible water pollution in the event of an accident, e.g. being in
the vicinity of a river, endangering potable water supplies,
etc.;
Hazard to the neighbourhood through explosion or fire in case of
adjoining residential areas, roads with heavy traffic, railway
lines, schools, hospitals, due to the immission of aerosols or
decomposition products or concurrent evaporation of stored products
released in firefighting, etc.;
- Impact of the neighbourhood on the facility: Traffic accidents in
the immediate vicinity involving reservoirs, neighbouring facility
with increased hazard potential, air traffic, earthquake risk,
flooding, climatic conditions, e.g. corrosive air from heavy
traffic, chlorine or chloride plants (salines), etc.
The site selection and decisions on the size of the tanks and the
farm as a whole must be made as part of a hazard analysis.
2.1.2 Planned arrangement When planning a tank farm attention must
be paid to: - A clear arrangement of the individual units (rows of
tanks, filling/discharging bays, piping
networks, pump groups); - Logical division of the complete facility
by individual protective structures and fire sections; - Products
which could react dangerously with each other or cannot be
extinguished with the
same fire extinguishing equipment must be stored separately in a
suitable manner; - Structural, hazard-oriented separation of tank
farms from production facilities, e.g. by safety
clearances, fire walls, water curtains, tank zone with
non-flammable liquids; - Escape and emergency routes (VKF Guideline
16-03d [9]) - Good accessibility for maintenance, operation and
event rectification;
TRCI 2 Planning and design of tank farms Page 10 of 70
TRCI Edition 2009
- The accessibility of tank farms for flammable liquids must be
safeguarded for mobile fire extinguishing equipment (vehicles) from
at least two sides and every individual tank must be accessible by
mobile fire extinguishing equipment from outside of the tank area
(Fig. 1+2). Within a group of tanks, the layout of the tanks should
be such that "shadow zones" (i.e. zones which the fire
extinguishing equipment cannot reach or only with difficulties) do
not occur in case of a fire. If this demand cannot be met due to
the operational situation, fixed firefighting installations must be
provided, firefighting from the top may also be taken into
consideration (Fig. 3 + 4);
- The distances between tank groups have to be defined according to
fire-extinguishing aspects (accessibility, possibility of inserting
water walls, etc.). It is advantageous to subdivide bigger tank
groups into smaller fire sections (e.g. by fireproof walls or with
tanks of non-flammable liquids in between).
Fig. 1 + 2 Tank farm accessible from two sides
F
Tank Farm Guidelines for the Chemical Industry
Perimeter, drainage In case a storage tank leaks, liquid sprayed
beyond the bed (spray parabola) must be collected and handled in a
controlled manner. The strip to be drained must have a width of at
least 0.5 times the height of the tank above the bed, measured from
the tank wall. If tanks are thermally insulated or if they are
equipped with protective cladding, this measure is not
required.
ig. 3 Tank farm only Fig. 4 Tanks inside of the tank field (shadow
accessible from one side zone) not accessible by mobile fire
extinguishing equipment or only with difficulties.
TRCI 2 Planning and design of tank farms Page 11 of 70
TRCI Edition 2009
0,5 x h
h
For the size of the drained area and retention volume at transfer
sites see Chap. 3. The surface of the tank farm perimeter which can
be wetted by leaking liquid during operation or in case of
accidents is to be of a structure impermeable to liquid, weather-
resistant and principally resistant against the goods stored there.
These areas are to be drained in a controlled manner.
2.1.3 Tanks in underground concrete spaces General comments Storage
tanks can be erected individually in underground concrete spaces;
this arrangement is predominantly employed, if site conditions
require the use of space under streets and yards. Structure On
principle, the structure is subjected to the same requirements in
relation to impermeability as normal protective structures.
Selection of tanks For liquids of Hazard Classes F1 and F2 only
explosion-resistant or blanketed tanks may be used. Liquids of
Hazard Classes F3 and F4 and hardly or non-flammable products can
be stored in tanks which are not explosion-resistant. Tanks in
underground concrete spaces must be designed without a bottom
outlet nozzle. Clearances The clearances between storage tanks and
protective structure are to be designed in such a way that visual
check of the storage tanks and the protective structures for
impermeability is feasible. Where this is not possible, a leakage
monitoring system is needed and the storage tanks have to be
checked and cleaned inside at appropriate intervals (at least every
10 years). 2.1.4 Filling points and drum filling points
Construction Filling points are preferably to be constructed as an
open or semi-open structure, where necessary with a roof for
protection against the elements. Easy detection of liquid losses
must be guaranteed. If liquids of Hazard Classes F1 and F2 are
filled, non-flammable construction materials are to be used and
sufficient separation in terms of fire protection has to be
arranged between the filling point, tank farm and the other
facilities and buildings. Containment trays, containment beds and
containment basins or their coating must be resistant to stored
media and leak-proof for at least 6 months, only in exceptional
cases for chemical- physical reasons, the authority issuing the
permit may allow a resistance to stored media for the period
required to identify the loss, repair the leak and remove the
liquid.
Ventilation If a closed type of structure is to be used for special
reasons, appropriate ventilation and accessibility is to be
particularly considered usually requiring induced ventilation. It
is to be ensured that ventilation apertures are available also
immediately above ground level.
Tank Farm Guidelines for the Chemical Industry
TRCI 2 Planning and design of tank farms Page 12 of 70
TRCI Edition 2009 Tank Farm Guidelines for the Chemical
Industry
In semi-open construction, the natural air change is usually
sufficient. Appropriate measures must be taken to prevent liquids
and escaping vapours from accumulating in rooms at a lower level,
or in sewers, pits and the like. See also VKF Guideline 28-03,
Chap. 5.5 [9].
2.2 Tank and protective clearance Tank clearance Minimum tank
spacing is defined as the effective clearance between tanks or
between a tank and the wall. Anything reducing the effective
dimension, e.g. thermal insulation must not reduce the minimum
clearance. If a leak occurs in the wall of a tank, the spray
parabola must be caught inside or outside of the tank bed (see Chap
2.1.2). Thermal insulation or protective cladding meets this
requirement.
Protective clearance Protective clearance is measured from the
outer edge of the protective structure of the tank farm to the
adjoining building under the same ownership or to the building line
of the neighbouring lot. The protective clearance can be reduced
after consulting the authorities, if suitable measures, such as
protective walls, deluge spray systems, or foam, are provided. For
tank diameters larger than 10m, it must be verified for each
product that the radiant heat on the building line of the
neighbouring lot does not exceed 8kW/m2 in case of a fire.
Calculation e.g. according to the Swiss Reinsurance Company [30].
2.2.1 Outdoor storage tanks and drum storage Based on the "Fire
Protection Guidelines, Flammable Liquids" [9], the following
standard values are applicable.
Table 2.2.1: Hazard to neighbourhood (degree of hazard)
Use of building
Fire hazard low1)
Fire hazard normal 2)
Fire hazard high 3)
Min. EI 60 (nbb) and facing wall without any openings small small
small
Min. not combustible small medium great
Combustible or no wall medium great great
Rating examples for type of use according to fire hazard: 1)
Manufacturing, processing and storage of non-combustible materials
and goods, metal processing 2) Machine manufacturing, offices,
apartments 3) Processing and storage of flammable or explosive
materials and goods, wood processing
TRCI 2 Planning and design of tank farms Page 13 of 70
TRCI Edition 2009 Tank Farm Guidelines for the Chemical
Industry
Table 2.2.2: Outdoor drum storage
Clearance from drum storage to buildings (in m) Hazard to
neighbourhood
(degree of hazard) Hazard Classes F1 and F2
Hazard Classes F3 to F5
Size of store (in m3) Size of store (in m3)
up to 5 up to 50 more than 50 up to 5 up to 50 more than 50
small 5* 10 15 - 5* 8
medium 10 15 20 5 8 12
great 15 20 25 8 12 15
* No protective clearance if the facing wall corresponds to EI 60
(nbb) and does not have any openings and the accessibility is
safeguarded.
The protective clearance refers to drum storage if the same drums
are stored for a longer period of time. Protective clearance to
railway tracks, high-voltage lines and motorways should be the same
as for tank farms.
Table 2.2.3: Minimum tank and protective clearance
Type of vessel Tank size Hazard class Protective clearance Tank
clearance A B X
2) Y
NBG high 20m
10m
0.5 m 1) 0.5 m 1)
F1 and F2 NBG low 20m
NBG medium 25m NBG high 30m
30m
15m
500m3
40m
NBG high 20m 20m
non-explosion- resistant
0.3 D, min. 1m
Clearance A and B (VKF), X (KVU), Y (TRbF / CARBURA) see the
following figure NBG: Danger to neighbourhood according to Table
2.2.1 D = Tank diameter, if there are various diameters the largest
one applies. 1) = 0.8m gangway on one side per tank row 2) = The
"perimeter, drainage" Chap. 2.1.2 must be met. 3) = At least the
Building Dept. regulations have to be met.
TRCI 2 Planning and design of tank farms Page 14 of 70
TRCI Edition 2009
(Building line) (Building line)
Explanation concerning tank and protective clearance (special
cases) "Fire Protection Guideline, Flammable Liquids" [9] Railway
tracks A protective clearance of 15m to the main tracks is
applicable according to the VKF Guideline (28-03) [9]. Further
details are also contained in the VKF Guideline. High-voltage lines
A protective clearance of 10m is applicable to high-voltage lines
[9]. Protective clearances to high-voltage facilities of third
parties are to be determined according to the directives of the
Swiss Federal High-Voltage Inspectorate Article 16, [23]. If these
clearances cannot be complied with, a commission of experts decides
on a case-by-case basis on compensatory measures. Roads
Tank Farm Guidelines for the Chemical Industry
A protective clearance of 10m is applicable to public roads (up to
the roadside) [9]. For motorways, a special Swiss clearance
provision in relation to tank farms does not exist. The building
lines must always be taken into account. The safety spacing, which
is applicable inside the works area, must be complied with as a
minimum clearance. Cantonal building authorities are empowered to
impose additional clearances from these building lines.
TRCI 2 Planning and design of tank farms Page 15 of 70
TRCI Edition 2009
2.2.2. Storage tanks in buildings Table 2.2.4: Minimum tank and
protective clearance for medium-sized, cylindrical
tanks
Tank Farm Guidelines for the Chemical Industry
F1
No protective clearance Building walls min. EI 90 (nbb)
Tank to wall 0.15m Tank to tank 0.25m Service gangway 0.5m Gangway
on one side (escape route) 0.8m
F5 Non-explosion- resistant
and No protective
clearance F6 tanks Tank to ceiling 0.7m
The minimum tank clearances refer to the effective clearance from
tank to tank or from tank to wall.
0,5 m
min 0,8 m
The clearance between tank (manhole flange) and ceiling must also
be ensured. Anything reducing the effective dimension, e.g. thermal
insulation, must not reduce the minimum clearance.
TRCI 2 Planning and design of tank farms Page 16 of 70
TRCI Edition 2009 Tank Farm Guidelines for the Chemical
Industry
2.2.3 Outdoor filling points and drum filling points At transfer
points for tank wagons, firm installations are to be located
outside of the clearance profile for shunting tracks.
Table 2.2.5: Minimum protective clearances of filling points
Hazard class To buildings and facilities outdoors
To building line on neighbouring lot
F1 and F2
10m NBG high 15m
NBG high 8m
NBG: Danger to neighbourhood according to Table 2.2.1
The clearances are determined from the manhole or from the outlet
nozzle. For explanations concerning the protective clearance and
measures to reduce the clearance as well as special cases see Chap.
2.2 To the pertaining tank farm, a protective clearance is not
required. Drum filling points Drum filling points for liquids of
Hazard Class F1 to F4 should have, in relation to buildings and
facilities, a clearance of at least 3m. For measures to reduce the
clearance see Chap. 2.2.
TRCI 3 Protective structures, foundations Page 17 of 70
TRCI Edition 2009 Tank Farm Guidelines for the Chemical
Industry
3 Protective structures, foundations 3.1 General comments The
structural design, dimensioning and the realisation of tank farms
are subject to standards and guidelines. These are, in
particular:
KVU Guideline [35-1.5] and [35-1.4] SIA 261, SIA 261-1, SIA 262,
SIA 262-1 [25] SN EN 206-1 [27]
The regulations and directives of the Federation, Cantons and SUVA
as well as standards based on the same are to be observed. 3.2
Protective structures 3.2.1 Definitions Protective structures are
constructions which make liquid losses (leakage or overfilling)
easily detectable in free-standing facilities or which retain
leaking liquid. - Discharge surfaces serve the secure discharge of
spray losses or leakages (e.g. suitable roads
and yards); - Connecting channels and connecting pipes between
discharge surfaces and basins; - Containment trays are waterproof
and weather-resistant structures and serve the easy
detection of liquid losses; - Containment beds are waterproof
structures principally resistant to stored goods and serve
the
detection as well as retention of leaking liquid. Leaking liquid
can also be retained by a separate containment basin;
- Containment basins are waterproof structures principally
resistant to stored goods and serve the retention of liquids
draining from trays and beds. They can also be used to burn off
flammable liquids;
- Firefighting water containment basins have to be provided for
tank farms with flammable liquids. A contingency plan must be
available for each case, based on the water quantities of the
fire-extinguishing concept.
3.2.2 Requirements of protective structures The requirements of the
KVU Guideline [35-1.4] are to be met. Protective structures must
thus be of concrete and placed on a ground which is capable of
bearing and frost-resistant. They must resist strains during
testing and operation, should not show any permanent deformation
and stay waterproof. In particular, the expected chemical strain
and earthquakes (see Chap 5.5) are to be taken into consideration.
The protective structure is to be dimensioned in such a way that it
is resistant to stored media for at least 6 months. In justified
cases, the authority issuing the permit may allow a resistance to
stored media for the period required to identify the loss, repair
the leak and remove the liquid. For protective structures in
Ex-zones, measures against static electricity are to be verified.
Separate containment basins are recommended for flammable liquids.
For checks and maintenance see Chap. 6.4 and 6.5. Repairs must be
agreed with qualified persons and sealings should be realised
according to the engineering rules.
TRCI 3 Protective structures, foundations Page 18 of 70
TRCI Edition 2009
3.2.3 Discharge surfaces Discharge surfaces shall be waterproof and
require a slope to the containment basin.
3.2.4 Containment trays The containment trays require a slope.
Containment trays without a slope require a curb of at least 10cm.
3.2.5 Containment beds, containment basins Containment beds,
containment basins for tank farms The overall area of a tank bed
shall not exceed 400m2 as a rule, otherwise the beds must be
subdivided into sections. To limit the water requirement for
cooling and foam blanketing in tank farms with flammable liquids,
the containment bed is to be divided into sections (e.g. for 2 to 9
tanks) and must have a slope of at least 1.5% so that in case of
leaks or overfilling, the liquid cannot spread out under the tank
but flows into a suitable containment basin or a separately
arranged pump sump (see the following diagrammatic figure).
Examples: Containment bed
min. 1,5%
Protective wall Siphon/check valve; may need protection against
freezing Separate containment basin quick, safe runoff of larger
quantities in case of damage
pump sump
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In areas where containment volumes are stipulated by law, openings
for piping or similar arrangements are not permitted in walls. In
exceptional cases, specially appropriate sealing techniques must be
used. The dividing walls are lower than the perimeter walls, but,
as a rule, are not higher than 0.5m in order to ensure
accessibility. Containment basins for liquid losses and drainage
for transfer sites If liquid losses have to be retained, the
following arrangements may be used as containment basins: -
Containment bed in the area of the transfer point; - Lower
containment basin of an adjacent tank farm if functioning of the
same is not impaired
and the transferred goods are not allocated to Hazard Class F1 or
F2. At filling points without any roofing, precipitation must be
collected and also channelled to the containment basins. The
availability of sufficient containment volume is to be checked
prior to every transfer. This must correspond to the maximum
quantity which may escape up to the rectification of the leak,
however, minimum 5m3 (see also KVU [35-1.1]). For the minimum area
of the containment tray for tank wagons and tank lorries see Chap.
7.1. 3.2.6 Size of protective structures Protective structures for
liquids of Class A must be able to retain at least 100% and liquids
of Class B at least 50% of the usable volume of the largest vessel.
Possible firefighting water and water from outdoor precipitation
are to be calculated in addition. Firefighting water containment
basin Containment trays and containment bed, possibly with a
separate containment basin, also serve firefighting water
containment. The level of the tank bed may only rise to a point
where the tanks are not lifted by buoyancy forces, if they are not
reliably anchored in this respect. In addition to the containment
volume for the tanks, it must be possible to retain at least the
firefighting water emerging from the fixed firefighting equipment
during 30 minutes as well as an appropriate quantity from the use
of mobile equipment (during 30 – 60 min.), if separate firefighting
containment basins are not available (for details of firefighting
water quantities see Chap. 4 and 5). Quantity of precipitation This
quantity must correspond to that for a long weekend (3 days at 25
l/m2 = 75 l/m2). Different climatic conditions may be taken into
account depending on the location. 3.2.7 Protective structures of
metal - Protective structures may only be of materials which are
sufficiently corrosion-resistant (see
Chap. 3.2.2); - The thickness of beds is to be determined by static
calculations, if required.
3.2.8 Protective structures of mineral-based building materials
Protective structures of reinforced concrete or prestressed
concrete consist of a concrete construction prepared on site and,
if required, of a sealing. The concrete structure must be designed
in such a way that occurring deformation, particularly creep and
shrinking deformation, does not have any adverse influence on the
sealing. Building materials: Only high-quality concrete according
to EN 206-1 [27], e.g. NPK C, may be used.
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3.2.9 Linings and coatings Linings and coatings are used as
sealings and corrosion protection in protective structures: -
Coatings based on epoxy resin or bitumen; - Laminates (reaction
resins from unsaturated polyester resin, from phenylacrylat resin
or from
epoxy resin free of solvents are to be used); - Plastic plates; -
Joint sealing compounds and joint tapes; - Ceramic linings; -
Metallic linings. Sealings of plastic material must have a
certificate for water protection capability of an accredited test
body (KVU [35-1.6]), must provide the required elasticity and stick
to the substrate (base). Foils of plastic material are fixed to the
walls (they do not stick to the substrate).
3.2.10 Testing of protective structures The manufacturer or the
erector must check and document the parts (KVU [35-1.4]). Testing
comprises: - Inspection of construction: Workmanship, conformity to
drawings; - Quality: Of materials and workmanship (in case of metal
beds, in particular the welding
seams); - Leakage testing: Water test or another comparable test
procedure (see Chap. 7.4 and 7.5). The manufacturer or the erector
must issue a test protocol on these tests which records the
results. The same must confirm that the part of the facility has
been constructed and tested according to the engineering rules and
the provisions of the TRCI. The test protocol is to be signed by
the manufacturer or the erector and to be delivered to the test
report administrator, the owner or the operator of the facility
latest upon the acceptance of the facility; the manufacturer or the
erector must keep a copy. In case of facilities requiring approval,
testing is to be respectively repeated after 10 years (KVU
[34-03]). 3.3 Foundations Foundations must be laid in frostproof
ground with a good bearing capacity. Dimensioning of the tank
supports and the pertaining foundations must be in line with the
expected static load as well as with the load-bearing capacity
provided for the respective region and the classification of
protection requirements in respect of earthquakes (see Chap. 5.5).
If the risk exists that a tank might float, the corresponding
buoyancy forces must be taken into account when calculating the
anchor bolts.
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4 Storage tanks and equipment Manufacturers of facility part must
check whether the same correspond to the engineering rules and must
document the test results (GSchG, Art. 22 paragraph 4 [1]). See
also KVU [35-1.6]. 4.1 Storage tanks 4.1.1 General comments, terms
This chapter covers medium-sized tanks (usable volumes 2 to 250m3)
of metal and plastic material as well as large tanks (usable volume
more than 250m3) of metal. Storage tanks of reinforced concrete and
prestressed concrete are not covered by the TRCI.
Terms - Standard volume: The standard volume is specified according
to the R5 series of standard
numbers and is smaller or equal to the nominal volume; - Nominal
volume: The nominal volume is the maximum quantity of liquid a
vessel can hold on
basis of the stress calculation and its technical construction; -
Usable volume: The usable volume amounts to 95% of the nominal
volume for drums, small
and middle-sized tanks, 97% of the nominal volume for large tanks;
- "Free-standing" storage tanks: see Chap. 1.6.1.
Requirements for storage tanks - Storage tank construction material
must be resistant to the stored medium (liquids and
vapours), protected against external corrosion and able to
withstand the expected thermal and mechanical stress (for metal
vessels see EN 12285-1 steel tank horizontal, Annex B [27]).
- For leakage monitoring, tanks can also be constructed with a
double bottom or a jacket (see Chap. 4.5.4).
- For flammable liquids, metallic (incl. coated and lined) storage
tanks are to be used. - Dimensioning of tanks and their supports
must take the additional forces resulting from an
earthquake into consideration (see Chap. 5.5). - Every medium-sized
tank or large tank must be equipped with at least one manhole (DN
600).
Small tanks must have at least one inspection hole. Classification
according to size (usable volume) - Drums 20 l to 450 l - Small
tanks above 450 l to 2m3 - Medium-sized tanks above 2m3 to 250m3 -
Large tanks above 250m3
Types of vessels - Drums Cans, barrels, etc. - Small tanks
and
medium-sized tanks explosion-resistant or non-explosion-resistant
prismatic or cylindrical Tanks with a domed or flat bottom; - Large
tanks Vertical, cylindrical vessels with flat bottoms are
differentiated as
follows: a) Vertical tanks where the free space above the stored
medium has free access to the atmosphere; b) Vertical tanks with a
fixed roof which can support a gauge pressure or
partial vacuum in the free space above the stored medium, according
to operating conditions;
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c) Vertical tanks with a fixed roof equipped with an internal
membrane floating on the stored medium (membrane tanks);
d) Vertical tanks whose roof is constructed as a float (floating
roof tanks).
Other types of vessels not listed above (e.g. spherical tanks) are
possible. 4.1.2 Storage tanks of metal Corrosion
When choosing the material and wall thickness, both safety against
corrosion (if corrosion is expected, additional costs should be
foreseen) and the economic efficiency are to be considered.
Explosion-resistant tanks A tank is considered explosion-resistant,
if it can withstand an internal explosion and still does not leak.
Storage tanks equipped with an inert gas blanketing system are
considered to be equivalent to explosion-resistant tanks in
relation to their use (hazard class). As a rule, they are used for
usable volumes of up to 250m3 for free-standing storage of highly
flammable liquids. - Construction according to BN 76 [36] and
Annex, explosion-resistant storage tanks (according
to BN 110 [36], flat-bottom tank).The vessel does not leak, even at
a maximum explosion pressure of 10bar. A major permanent
deformation is acceptable. The tank is operated unpressurised,
although a breathing pressure of +200mbar is permissible. Vacuum
resistance according to construction drawing;
- Construction according to BN 98 [36], explosion-resistant vessels
and equipment for flammable liquids and dusts. Designed for a max.
explosion pressure or for an explosion pressure reduced by means of
relief devices or explosion suppression (see VDI Guideline 2263,
[26]). Only small localised permanent deformation may occur. Any
desired operating pressure can be taken into account in the
calculation;
- For horizontal tanks (installation under or above ground)
explosion-resistant or non-explosion- resistant see EN 12285-1 or
-2 [27];
Calculation and testing according to BN: Dimensioning and stress
analysis calculation is according to BN 76 and Annex or BN 98. The
position, number and nominal width of the required nozzles,
manholes and supports are defined in dimensional drawings or
sketches (e.g. according to BN 110). The manufacturer must
initiate, at one of the listed offices (Switzerland: e.g. SVTI),
the preliminary check of the calculation and construction drawing
as well as the acceptance after production. Vertical tanks
Free-standing vertical cylindrical tanks with a flat bottom resting
on a base and a fixed roof (with or without a floating ceiling) or
with a floating roof can be used for the storage of all liquids at
atmospheric pressure or a slight operating gauge pressure.
Calculation and testing: According to SVTI regulations P 5,
[24].
Prismatic tanks The vessels must be constructed in such a way that
they are resistant to the static head of liquid and to pressures
and partial vacuums occurring during operation as well as external
stress. If these tanks are tested with a minimum of 0.5bar gauge
pressure, they are authorised for the free- standing storage of
liquids with flash points of more than 55°C. Calculation and
testing: According to SVTI regulations P 2, [24].
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4.1.3 Storage tanks of plastics Generally used up to 100m3 usable
volume for storage of potentially water polluting liquids with a
flash point of more than 55°C. Calculation and testing: According
to engineering rules, e.g. of the Plastics Association of
Switzerland (KVS). In case of a deviation from the technical rules,
evidence must be provided that the legal requirements have been
fulfilled in another way.
4.1.4 Heating and cooling systems The following methods are
available - Jacket around the tank or pipe wall; - Half coils or
heating panels welded to the outer tank walls; - Tubular coils or
heating panels inside of the tank; - Tubular coils touching the
outer wall of the tank or pipe, possibly embedded in heat
transfer
cement for improved heat transfer; - Electric heating system by
cables or elements; - Closed refrigerant system with circulation
pump and cooling machine. - Direct vapour injection into the stored
medium; - Re-circulation of the stored medium through a heat
exchanger; - Induction-heating systems, which transfer the
electrical energy directly into the stored
medium, can be considered for heat exchangers and non-flammable
liquids; - Tank sprinkling with water. Remarks - The surface
temperature of the heating elements or the heating medium
temperature to heat
flammable liquids must be adhered to according to TR BCI 155, Table
3.3.4-1 [36]; - A heat transfer medium which is non-flammable or
flame retardant and frost-resistant and
whose boiling point is above the maximum heating temperature is to
be preferred in order to avoid system pressure due to vapour
tension, e.g. mixtures of water/ethylene glycol;
- Any heat transfer medium used must not cause a dangerous reaction
when in contact with the stored medium;
- Electric heating systems and tracing systems for pipes have the
advantage of a uniform heat transfer (W/m2), cost-effective
division into individual pipe sections, virtually not heat loss and
they represent an economical method of supplying heat energy;
- For hazardous zones, heating elements require an Ex test
certificate.
Cooling procedures Cooling equipment as described above. The
refrigerant should be non-flammable or flame retardant, and must
not be too viscous at low temperatures, e.g. refrigerating
brines.
4.1.5 Inert gas blanketing In order to avoid the ingress of air
into storage tanks, the liquid is blanketed with inert gas (e.g.
N2) (see ESCIS Volume 3, [17]). To keep the consumption of the
inert gas as low as possible, a large permissible difference
between the gas supply pressure and the relief pressure is used.
For breathing, automatic pressure relief valves or overflow valves
as well as controllers with auxiliary power can be used. They are
selected according to tank stability and properties of the stored
medium. The set pressure of the control valves must be aligned to
the response pressure of the safety valves.
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If a storage tank according to BN 110 is used for non-flammable
media or flammable media under inert gas blanketing, the maximum
permissible operating gauge pressure amounts to +500mbar, otherwise
max. +200mbar. Vacuum protection according to the permissible
operating negative pressure of the tank (see details in
construction drawings).
Example: For a tank according to BN 76 / BN 110:
N
Tank Farm Guidelines for the Chemical Industry
2-gassing by automatic low pressure reducing valve; e.g. set point
15mbar. N2 relief by automatic overflow valve; e.g. set point
80mbar (max. permissible 200mbar).
4.1.6 Tank surface coating - Function: In addition to its main task
of protecting the storage tank against corrosion, the tank
coating can also influence warming of the tank and thus breathing
losses. The painting system to be used for carbon steel tanks is
specified. e.g. by the following guidelines: · BN 108 according to
System WBZ or SBZ; · For insulated tanks, coating with System AB or
2U according to BN 108 is recommended; · Non-insulated tanks with
primer and topcoat according to BN 108, according to System
WBZ or SBZ; · Colour of the topcoat as desired; preferred shades
Al-silver to white with a total heat
reflectance factor W above 70% (see table below). R Special coating
materials may also be used as fire protection measures;
- Influence of the surface coating on tank warming: According to
VDI Guideline 3479, [26] there is a linear relationship between the
surface temperature of a hollow body and the total heat reflectance
factor. The surface temperature of a body painted in black can be
up to 25°C higher in central Europe than that of a similar body
painted in white.
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The table below, provides an overview of the total heat reflectance
factor WR for the wavelength spectrum of natural sunlight (300 to
4200nm) for various coating colours.
Description of the colour
Total heat reflectance factor
WR in % (rounded off)
Black RAL 9005 3 Machine grey RAL 7031 10 Brown RAL 8011 12 Mouse
grey RAL 7005 13 Green RAL 6010 14 Blue RAL 5010 19 Silver grey RAL
7001 27 Pebble grey RAL 7032 38 Red RAL 3000 43 Light grey RAL 7035
51 Ivory RAL 1014 57 Aluminium silver RAL 9006 72 Creamy white RAL
9001 72 White RAL 9010 84
Surface coatings: The total heat reflection factors given above as
examples were determined for freshly completed coats of paint; they
thus correspond to "good paint conditions". For an exact
calculation see VDI Guideline 3479, [26].
4.1.7 Thermal insulation Thermal insulation (see e.g. BN 56 and BN
58) may be used: - In heated tanks; - For the reduction of
temperature fluctuations in the gas space of tanks and thus for
the
reduction of breathing losses; - As fire protection to prevent the
storage medium and the construction from heating up fast
instead of tank cooling (see Chap. 5).
If thermal insulation has been provided as a fire protection
measure, it has to be designed in such a way that dangerous
conditions cannot arise at any filling level in the tank for 30
minutes. This requirement is fulfilled, on principle, if BN 111 is
used. In this case, the following aspects are to be observed: -
Insulating materials must have a Fire Hazard Index of 6
(non-flammable). Mineral fibre
sheets bound with wire netting (without any plastic components) and
mineral fibre fire protection sheets (coated on one side with
aluminium foil) are examples of suitable materials;
- The insulating materials must be securely fastened. If, for
example, mineral fibre fire protection sheets are used with
aluminium as cladding, the fire protection sheets must be secured
additionally with a wire mesh;
- Tank legs or skirts must also be protected. If it is possible for
fire to enter beneath the tank, then this part including the piping
and valves and fittings must also be protected;
- If other materials are used instead of mineral fibres or foamed
glass (e.g. sublimation coatings, sprayed cement, etc.) their
suitability must be checked by an authorized institution;
- The danger of self-ignition of organic liquids which can soak
into the insulation must be assessed in relation to local
conditions. Mineral fibres or open-celled material must only
be
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used after carrying out a hazard assessment. Where necessary for
safety reasons, a closed-cell material such as foamed glass must be
used.
With insulated tanks it must be taken into account that if heat is
generated within the tank due to an exothermic reaction, cooling
from outside is not effective. 4.2 Piping 4.2.1 General comments,
terms - Piping includes: Pipes, valves, fittings and connecting
elements which connect storage tanks
transfer sites, pumps and production plants; - "Freestanding or
buried" piping: see Chap. 1.6.1. - Hoses are connecting parts
of
· Elastomeres or thermoplastics; · Parallel corrugated, braided
hoses of stainless steel and the pertaining hose fittings.
4.2.2 Requirements of piping - In relation to design,
manufacturing, installation, testing and safety facilities, piping
(with a
permissible operating pressure ps above 0.5bar) has to fulfil the
requirements of the European Pressure Equipment Directive (PED)
[29];
- The piping materials and valves and fittings must be resistant to
the medium being transferred (liquids and vapours) and protected
against external corrosion as well as the expected thermal and
mechanical loads. For leak monitoring, piping can also be equipped
with a jacket (see Chap. 4.5.4). For piping of steel, copper and
plastics, see also KVU [35-1.2] Chap. 3.4;
- For flammable liquids, metallic (incl. coated or lined) piping
must be used. Connecting parts of elastomeres, e.g. hoses, require
a hazard analysis;
- Depending on the medium, measures in relation to electrostatics
have to be taken (see Chap. 5.2.5);
- Piping must be designed for at least PN 10. Exception: Pipes of
plastic materials minimum PN 4, however, connecting parts must also
be PN 10;
- On principle, any liquid loss from piping must be easily
detected. In case of buried piping, liquid losses must be
retained;
- Piping and its support must withstand earthquake loads (Chap.
5.5); - To reduce the possibility of leakage, all system parts
shall be welded wherever possible.
Excluded are parts which need to be removed such as control valves,
safety valves and fittings, etc. For further information see DIN
4754, [28].
4.2.3 Design, installation - Whenever possible and expedient,
pipelines must be installed above ground, and be visible
and accessible. They should, however, be largely protected against
possible damage; - Determination of distances for piping supports;
- Avoidance of impermissible pressure surges (e.g. in closed pipes,
pressure blows) see also
DGV [29]; - The number of joints between individual pipe sections
and valves and fittings that can be
disassembled must be kept to a minimum, and must be easily and
safely accessible. For increased protection against leakage,
special measures (e.g. tongue and groove and flanges or special
gaskets) are to be provided;
- For pipe leak monitoring purposes and leakage containment, e.g.
double-walled pipes can be used;
- In case of dangerous liquids a check has to be conducted as to
whether detachable joints at exposed locations need any special
spray guards for personal protection.
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4.2.4 Connection of pipes to tanks and tankers - Any re-siphoning
of liquid from the tank via an immersion pipe must be prevented
by
technicalmeans (e.g. vent holes);
- If pipe connections are required under the level of the liquid,
special tank valves and fittings must be used (see Chap.
4.3.2);
- If hoses are used as a connection between mobile tanks or tankers
and fixed piping see next chapter;
- Instead of hoses, articulated pipes can be used as floor arms or
wall or gallery arms for connections at the bottom or top of a
mobile tank or tanker. These have to be selected according to
medium requirements and are to be identified and tested by an
authorised inspector;
- Measures against electrostatic hazards (see Chap. 5.2.5).
4.2.5 Hoses Hoses are particularly used in tank farms to - connect
mobile and fixed parts of facilities; - load and discharge tankers,
tank wagons or containers.
Hoses should only be used as a permanent alternative to fixed
pipes, if the advantages offered by their use cannot be abstained
from (they should not be just a "convenient substitute" for a fixed
pipe). A hazard analysis must be carried out. It may be that
additional safety measures are needed. If hoses are used, the
instructions of ESCIS, [17] and the "BG Chemical Bulletin" [31] are
to be taken into consideration. The safe use demands that - The
hose quality is carefully selected for the respective conditions of
use; - The hoses correspond to relevant standards and the state of
the art and that they have been
tested; - There is an unambiguous identification of the hoses (see
DIN 2823 a. 2827 [28]); - The hoses are appropriately stored; - The
hoses are manufactured, assembled and installed by skilled persons;
- The hoses are used as intended (regular training of operators); -
Regular tests are conducted; - Depending on the medium, measures in
relation to electrostatics are taken (see Chap. 5.2.5). 4.2.6 Gas
balance, pressure compensation lines - It must not be possible to
isolate vent lines (pressure compensation lines). If outlets lead
into
the atmosphere, they must be protected against the ingress of
rainwater and dirt and must be positioned in such a way that
escaping vapours can dissipate without representing a hazard. The
minimum nominal pipe diameter amounts to DN 40 (Exception:
Ventilation by pressurised inert gas);
- Facilities in the vicinity, e.g. ventilations, stacks, sewer
systems, lights and lift shafts, are to be taken into
consideration;
- The dimensions of pressure compensation lines must be sized in
such a way that dangerous gauge or negative pressure cannot result
when tanks are rapidly filled or discharged or rapid temperature
fluctuations occur. The pressure losses of vent systems and flame
arrestors must be taken into account;
- To determine the max. breathing volume flow, the formulae
according to TRbF [15] may be used;
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- In gas balance and pressure compensation lines, possible
condensate formation must be taken into account;
- The installed pipes usually need a slope towards the tank,
otherwise a drainage device must be installed on the lowest
point;
- Several tanks may be vented by a common pipe, provided the
different media do not enter into any dangerous mixtures,
condensation or solids formation with each other.
4.2.7 Overspill, overflow equipment The arrangement must ensure
that leaking liquid flows into the protective structure in case of
overspilling (see KVU [35-1.3]). 4.2.8 Distributing and return
lines If a filling line serves several tanks, it must be ensured
that overspilling of these tanks is prevented (see Chap. 4.5.3). If
facilities use return lines, it must be ensured that the return
liquid flows into the vessel from which it was taken. Incorrect
connections must be excluded (see KVU [35-1.2]).
4.2.9 Testing of piping Piping must be tested by the erector in
accordance with applicable regulations (e.g. DGV or TR BCI 151).
Testing comprises: Non-destructive testing (e.g. visual, radiation
and/or penetrating tests), pressure testing and leakage testing.
Leak detection pipes are to be tested according to KVU [35-1.2]. A
protocol is to be prepared for conducted tests.
4.2.10 Pipe insulation Pipe insulation may be designed, e.g.,
according to BN 55 and BN 56.
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4.3 Valves and fittings 4.3.1 General comments - Valves and
fittings must be able to withstand the same loads as piping; - They
are to be arranged in an accessible manner and easy to operate; -
The measures to safeguard impermeability in relation to the
atmosphere must correspond to
the hazards associated with the medium, e.g. bellow seal valves or
diaphragm valves with backup stuffing boxes.
4.3.2 Shutoff valves Shutoff valves at the tank which are subject
to the static head of the tank contents must fulfil the following
requirements: - They must be installed directly on the tank; - They
must be resistant to frost (i.e. they cannot be destroyed by the
effects of frost, and frost
does not make them less effective); - In case of disk valves, the
static head of the tank contents must support the closing effect; -
When the valve is closed, the stem stuffing box must not be subject
to the static head of the
liquid in the tank. Piping components, flange connections and
shutoff valves which are subject to the static head of the tank
contents must be able to withstand a fire in the tank basin and
stay tight. It is therefore recommended, e.g. in tanks with bottom
outlets, to install a shutoff valve directly on the tank which
closes itself without external energy in case of a fire. In case of
pneumatically operated valves, flammable control air connections
are thus to be used. In addition, the shutoff valve should be
either fireproof or protected by insulation or cooled by a deluge
spray system.
4.3.3 Vent valves If the gas space in a tank is separated from the
atmosphere or from a connected exhaust air system a vent valve is
needed. - Mechanical (dead weight or spring-loaded) control valves
or seal pots can be used as vent
valves. The response pressure is to be selected in such a way that
the pressure change (depending on the type of valve 10 – 100% of
the response pressure), which is reached at the max. volumetric
flow rate, causes the design gauge and negative pressure to be
adhered to. In the determination of the volumetric flow rate, that
of breathing (Chap. 5.1.2) as well as that of the filling or
discharging pump (ISO 28300 [[20]]) is to be taken into
consideration;
- Commercially available breather valves involve high maintenance
costs to ensure the reliable impermeability of the valve seats. For
small pressure differences, seal pots offer higher operating
reliability; for larger pressure differences pressure/vacuum relief
valves with actuators controlled by external energy should be
installed. It must be ensured that if the external energy supply
fails, backup relief devices still provide protection;
- If the vent devices are not adequate to cope with a major mishap
(failure of the blanketing gas valves), additional relief valves or
bursting disks can be installed;
- Fire emergencies must be covered by other safety measures.
4.3.4 Flame arresters Flame arresters are devices which are
installed at the opening of a part of equipment or in the
connecting pipe of a facility system; their intended function is to
facilitate flow but prevent a flame front from entering the
system.
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Explosion in piping: The pipe deflagration is an accelerated
explosion in a pipe. Having passed through an instable transient
region, it becomes a stable detonation. In this detonation region,
which is stable again, temporary pressures of more than 80bar can
occur. In addition to the "dry" devices subsequently described,
"wet" devices (liquid seal chambers), fast-acting valves, devices
for suppressing explosions or other specific solutions may be used
for certain applications. Types of dry devices Dry flame arresters:
Are based on the principle of dividing the flow cross section,
e.g., into narrow passages in which flame propagation is no longer
possible. Only those devices may be used, which - according to
94/9/EC ("ATEX 95“) [[32]] and EN 12874 [[27]] - are approved by an
inspection authority for the intended purpose of use (explosion
group, operating temperature/pressure, etc.). Flame arresters are
classified according to the combustion process (endurance burning,
deflagration, detonation as well as their variants) and according
to the type of installation (explosion end, volume or pipe
arrester). Endurance-burning-proof devices: Prevent the propagation
of a flame front in case of prolonged burning of a combustible-air
mixture and/or in case of an atmospheric explosion. The device must
withstand the occurring temperature and pressure load. In case of
endurance burning, the flame must be able to burn off freely.
Deflagration-proof devices: Are devices which prevent the
propagation of a flame front in case of an explosion (observe the
max. permissible L/D ratio) and withstand the occurring thermal and
mechanical load. Mostly, they are not endurance-burning-proof.
Depending on the individual application and the purpose of
protection deflagration end, deflagration volume and deflagration
pipe arresters are installed. Detonation-proof devices: Prevent the
propagation of a flame front in case of an explosion and in case of
a detonation and withstand the occurring pressure load.
Detonation-proof flame arresters, however, are not in themselves
resistant to endurance burning. Application guidelines Substances
involved: - Flammable liquids with a flash point below 55°C; -
Liquids with a flash point above 55°C, if the flash point is not at
least 5°C above the liquid
temperature. Protected installations: - Vent outlets and other
openings, such as level gauge tubes which are open to the
atmosphere
or which are led into other gas-filled spaces; - Gas balance lines;
- Liquid lines which can run empty in the course of operation and
which are not separated by a
self-closing shutoff valve from the atmosphere or other facility
parts.
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Installations not requiring protection: - Openings which as a rule
are closed, e.g. manholes, dipstick, sampling and cleaning
openings; - Inlet and outlet lines which are continually filled
with liquid during operation; - Vent nozzles directly open to the
atmosphere on explosion-resistant tanks; - Blanketed tanks -
Discharge lines after safety relief valves. Installation guidelines
- Vent nozzles and short vent lines (L/D less than 20) must
terminate at their free end with an
endurance-burning-proof flame arrester; - Longer vent and gas
pressure balance lines must be provided with detonation-proof
flame
arresters and located immediately next to the tank or equipment
which is to be protected; - If the vent lines from several tanks
are brought together in a common header, as a rule, a
separate detonation-proof device must be installed immediately in
front of each tank; - Larger facilities must be divided into
emergency compartments to prevent a fire, explosion or
detonation from spreading; - The pressure drop in flame arresting
devices and the associated piping must not go beyond the
permitted gauge pressure/vacuum of the tank at the maximum
occurring volumetric flow rate; - Flame arresters must be protected
against the ingress of foreign matter. Restrictions in the use of
dry devices Flame arresters for media which tend to - foul -
polymerise - corrode - solidify - freezing in tight gaps are to be
replaced by other safety devices (see above). Appropriate heating
of the device (not possible for all devices) can prevent the danger
of freezing or solidifying in many cases.
Safety, maintenance and checks (SIWAKO) To ensure adequate
protection by flame arrestors, these must be periodically subjected
to a visual check. The intervals and the type of cleaning used
(mechanical and/or chemical) depend on the instructions of the
manufacturer and the conditions at the site involved.
4.4 Pumps Pump types are to be selected according to tasks (e.g.
filling or discharging of tanks), the medium (e.g. flammable
solvents or acids, liquids with high viscosity) and the
installation location (e.g. on top of or next to the tank). For
critical liquids sealless pumps or pumps with double mechanical
seals are required. Simple mechanical seals or even stuffing boxes
can be sufficient for less critical pumps. For different pump types
different monitoring systems are recommended or even required. For
canned motor pumps, storage monitoring (temperature, bearing
vibration) is stipulated for flammable liquids. For magnetic clutch
pumps, monitoring of the shroud is recommended, depending on the
medium. Pumps may only be in operation as long as this is required
for the conveyance of liquids. Pumps must be automatically stopped
if filling or dry-running safety devices are activated.
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Flowrate when filling storage tanks (according to KVU [35-1.1]):
The Flowrate in small tanks must not exceed 200 l/min (12m3/h), in
medium-sized tanks 800 l/min (48m3/h). In gravity discharge, 1’800
l/min (108m3/h) may not be exceeded. Dry-running interlocks for
pumps Dry-running interlocks must be installed in tanks containing
flammable liquids without inert gas blanketing in order to prevent
that an ignitable gas mixture enters the pump (tank running dry).
They also avoid dry-running and resulting pump damage. Different
types are available: - Level switch (LS); - Flow switch (FS); -
Instruments for current/power monitoring. For Ex-protection, the
ATEX Guideline [32] is to be taken into consideration (see also
Chap. 5.2.). 4.5 Instrumentation and control systems 4.5.1 General
comments, terms General comments Instruments and equipment must be
defined in accordance with expected loads and environmental impacts
and protected, if required. In particular control devices and
sensors of overspill protection systems, leak detection devices as
well as automatic level instruments must have a certificate for
water protection capability of an accredited inspection authority
(KVU [35-1.6]).
Terms - Overspill protection: Systems which prevent storage tanks
and mobile container from being
overfilled; - Special overspill protection: Storage tanks in the
chemical and pharmaceutical industry
usually use special overspill protection systems. These comprise
sensor, control device, shutoff valve and alarms. For special
requirements see CSME [19].
- Leak detection systems: Enable the identification of liquid
losses from tanks and piping. 4.5.2 Level instruments (level
measurement) Storage tanks must be equipped with level instruments.
Level instruments are devices which indicate the level in % or the
liquid quantity according to volume or weight. On principle, level
instruments must be used without a connection (nozzle) below the
level of the liquid (KVU [35- 1.3]).
4.5.3 Overfill protection Overfill protection systems must ensure
that the maximum permissible level in a tank or transport vessel is
not exceeded using by cutting of the liquid supply automatically
and triggering an alarm. This measurement system should be
independent of the level measurement system and should preferably
use a different measuring principle. This requirement is also
applicable if tanks are connected by a common filling line. The
overfill protection must be allocated to the tank which is to be
filled (see KVU [35-1.2]). Storage tanks in the chemical and
pharmaceutical industry usually use special overfill protection
systems (see above).
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The maximum permissible level corresponds to the usable volume (see
Chap. 5.1.1) for liquids stored at room temperature. Fill and
special overfill protection systems must correspond to engineering
rules.
4.5.4 Leak detection systems If liquid losses cannot be easily
identified visually, a leak detection system must be installed. The
same enables the detection of liquid losses from tanks and piping.
- Leak detection systems for vertical tanks with double
bottoms:
The negative pressure between the two bottoms must be monitored and
recorded at least once a month for control purposes;
- Leak detection systems for double-walled vessels and piping: The
gauge or negative pressure in relation to the atmosphere between
the two walls of the component must be monitored. If this monitored
pressure deviates from a predetermined set value, an alarm must be
triggered;
- Leak detection systems with liquid sensors: Liquid sensors detect
any losses at the lowest point in the space between the walls of
the component or at the lowest point in the protective structure
(pump sump) and trigger an alarm;
- Leak detection systems with gas detectors: Gas detectors identify
gases and vapours escaping from leaks in piping and vessels and
trigger an alarm;
- Leak detection systems for vertical tanks with double bottoms:
Buried double-walled vessels and piping require a test
certificate.
4.5.5 Temperature switch / electric circuit breaker Electric
heating systems require a fault current circuit breaker (FI switch)
for TN systems or an isolation-monitoring instrument for IT
systems. Redundant temperature safety switches are required for the
temperature protection of resistance heating cables.
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5 Ecology, safety and fire protection 5.1 Displacement and
breathing losses The emission losses of a facility must range
within the permissible LRV limits (see Chap. 7.2).
5.1.1 Displacement losses Displacement losses arise during tank
filling. For tanks vented to the atmosphere, the volumetric rate of
discharge is usually provided in a sufficiently accurate manner by
the pump discharge rate. Possible measures for reducing these
losses are: - Pressure balance line - Other measures for breathing
losses Apart from breathing (see below) also the volume flow of a
discharging pump has to be taken into consideration in tank
venting.
5.1.2 Breathing losses Breathing losses occur due to changes in
atmospheric pressure and temperature. The most important parameters
influencing breathing losses are: - Saturation of the space above
the liquid with vapour. This is principally determined by the
temperature in the gas space and the liquid together with the
frequency and the extent of the transfer;
- The physical properties of the liquid, such as vapour pressure
and latent evaporation heat as a function of temperature;
- The meteorological conditions at the storage location, such as
outside temperature, direct and diffuse radiant heat, the effects
of wind, strong precipitation (e.g. thunder storms), etc.;
- The condition of the tank surface, e.g. thermal insulation,
colour, etc.
The volume of gas breathed due to a temperature increase in the gas
space is to be determined by means of the gas equations. In case of
highly volatile liquids, the change in the gas constant due to
widely varying vapour contents at the temperature prior to the
increase as compared to the temperature after the increase must be
taken into account. The breathing loss is calculated using the
breathing volume and the degree of saturated vapour. For storage
tanks with rare transfers, 100% vapour saturation is assumed. For
storage tanks with daily transfers, a relative vapour saturation of
approx. 57% in winter and 63% in summer may be assumed, e.g., for
substances similar to petrol (VDI Guideline 3479, [26] and ISO
28300 [20]). Apart from the flowrate of a discharging pump, also
the flowrate due to a temperature decline is to be taken into
consideration for purposes of tank safety (negative pressure).
Rapid cooling, e.g. by strong rains, is to be included (see ISO
28300 [20] in this respect).
Temperatures in storage tanks: Annual measurements of the gas
temperatures above the stored liquid in an uninsulated, flat-
bottom and half-filled tank of 100m3 SS resulted in the following
values at an outdoor site near Basle in 1989: - Annual extreme
values (absolute max. or min. temperature): tmax = 45°C, tmin = 0°C
- Monthly fluctuation (difference highest/lowest temperature): t =
30°C - Daily fluctuation (difference highest/lowest temperature): t
= 25 °C - The max. temperature rise due to the weather amounted to
approx. 5°C/h. On exposed sites (e.g. in the Canton of Valais) the
span between the extreme values throughout the year and the monthly
and annual fluctuations must be increased by 5° to 10°C. The daily
temperature fluctuations of the stored liquid are very small,
depending on the filling
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level. Measurements have shown that the temperatures agree with the
respective daily average temperatures.
5.1.3 Measures to prevent or reduce emissions Two-pressure control
systems: Tank breathing can be regulated by a two-pressure control
system. At a set gauge or negative pressure, air (or nitrogen) and
vapour is discharged or air (or nitrogen) admitted. For some stored
liquids, the daily gas space pressure fluctuations can be
compensated with this set pressure difference without any gas
losses. Thermal insulation: Thermal insulation on a free-standing
tank or locating a tank in the earth reduces the daily temperature
fluctuations in the gas space to a few centigrades. The long-term
temperature fluctuations take place so slowly that discharging into
the atmosphere frequently ranges within LRV tolerance values.
Thermal insulation, if designed according to BN 111, also provides
advantages in relation to fire protection. Tank sprinkling: This
method is used to reduce the daily temperature fluctuations in the
gas space above the stored liquid. This method is suitable to avoid
temperature extremes. As a rule, however, permanent sprinkling
cannot be considered because of the water consumption. Cold traps:
The gases leaving the tank are cooled, the evaporating liquid
condenses with the exception of a small residual amount and the
condensate can be returned to the tank. Blanketing liquid of low
vapour pressure: Represents an ideal method to prevent the space
over the liquid from becoming saturated with vapour, however, only
rarely is there a suitable blanketing liquid for the liquids
normally stored. The measure may be used, e.g. in effluent storage.
Roofing: This protects the tanks from direct sun radiation and
results in lower daily fluctuations in the temperature of the gas
space. As a rule, this method alone is not sufficient to keep the
breathing losses within the LRV tolerance values. In addition,
roofing is very undesirable if an automatic deluge spray system is
not available in case of a fire. Exhaust air treatment: This
concerns the treatment of the gas volumes discharged from tanks in
facilities established for this purpose, e.g. incinerators,
biofilters, adsorption with subsequent desorption and product
recycling, etc. Floating roof or floating membrane: The liquid
surface is covered by the tank roof floating on it or, in the case
of fixed roof tanks, by a floating membrane. When the liquid level
falls, however, all of the liquid still wetting the tank wall is
lost to the atmosphere. Reflecting coats of paint: See Chap.
4.1.6.
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5.2 Liquid losses Potentially water-polluting liquids are allocated
to 2 classes (Chap. 1.5.1). Different water pollution control
measures are required according to the water pollution control zone
(Chap. 1.4). In order to avoid or retain liquid losses,
organisational measures are also to be taken into consideration
apart from structural and equipment measures. For details see -
Chap. 2.1.2, Planned arrangement (drainage in tank surroundings); -
Chap. 3, Protective structures, foundations; - Chap. 4.2, Piping
(requirements, design, …) - Chap. 4.5, Instrumentation and control
systems (against overfilling or leak detection
systems); - Chap. 6.4, Operation and maintenance 5.3 Plant safety
5.3.1 Ex-zone classification If flammable liquids are stored or
transferred, the areas concerned are to be classified and
identified according to Ex-zones as well as explosion groups and
temperature classes corresponding to the stored goods. The
classification can be performed on basis of SUVA Bulletin 2153,
[16] and TR BCI 155 [36]. Only equipment parts may be used which
conform to the respective zone, explosion group and temperature
class.
5.3.2 Measures against hazardous effects of electric currents The
following measures are required for tank farms located in areas
influenced by other external electrical facilities and industrial
lines (EMC see TR BCI 119, [36]): - The tanks must be protected
against corrosion due to stray currents; - It is thus required to
have all electrically conducting components meshed as thoroughly
as
possible; - Stray currents from rail and industrial installations
must not cause any undesirable effects,
such as spark formation or potential differences; - The type of
protection of the electrical installations must be commensurate
with the product
and local conditions and must be specified by the authorities and
the operator. The highest hazard class to be expected in the future
must be used (see Chap. 1.5.2);
- Underground piping, which is not electrically insulated, must be
protected against external influences. Special attention must be
paid to the effects of metal DC cables laid in the earth and on
foundations;
- Rules to judge the explosion hazard in facilities with hazardous
areas as well as the zone classification are contained in SUVA
Bulletin 2153, [16];
- For proper EMC (electromagnetic compatibility) installations see
TR BCI 119. Devices and protective systems as well as auxiliary
equipment used in hazardous areas must conform to the ATEX
Guideline [32] and the VGSEB [33].
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5.3.3 Lightning protection systems The SEV 4022 [23] lightning
protection provisions must be met (see also SN EN 62305-1 to 4
[27]). For outdoor installations storing flammable liquids,
different measures are to be taken in accordance with their flash
point (under or above 55°C). All devices with electric cables
leading into the tank interior must be equipped with a lightning
protection system. It is not required to protect the other
instruments (see SEV 3425 [23]). Lightning protection system -
External lightning protection system (arrester line); - Internal
lightning protection system (potential equalisation), see sketch in
Chap. 7.6. For EMC and lightning protection/earthing see also TR
BCI 119 [36]
5.3.4 Protection against electrostatic charging For flammable
liquids the hazard of electrostatic charge has to be considered
(e.g. correct earthing, use of conductive hoses, no insulating
coating). Measures to be taken are included in TI BCI 8 [36]. This
is applicable to - Flammable liquids with a flash point below 55°C;
- Liquids with a flash point above 55°C, if the flash point is not
at least
5°C above the liquid temperature. - Mixed liquids with a flash
point above 55°C, if the flash point is not at least 15°C above
the
liquid temperature.
5.3.5 Safety measures in case of an energy failure In case of an
energy failure (electric power, control air, nitrogen, vapour,
water, etc.) the measures are to be defined in accordance with the
risk analysis and all transfer operations must possibly be
interrupted. I.e. valves assume the predetermined safety setting,
transfer pumps are automatically switched off. Restarting is to be
governed by operating instructions.
5.3.6 General safety measures Special product properties For
products, which can have a dangerous pressure or temperature
increase because of a quick reaction, e.g. polymerisation, special
safety measures must be specified. Inspection The operator shall
inspect tank farms regularly to monitor their safe operation and to
eliminate any defects. This is in addition to the maintenance and
inspection work according to Chap. 6.4 and 6.5. Railings,
stairways, platforms Railings, platforms, stairways and ladders are
to be constructed in accordance with Ordinance 4 concerning the
Labour Act [18] and the EKAS and SUVA Guidelines and "Merkblätter".
Roads The roads next to vehicles are to be kept free during the
whole period of transfer so that the unobstructed departure and
access of emergency vehicles is possible at any time. The vehicles
have to be protected against rolling and collisions with other
vehicles by constructional and/or organisational measures.
TRCI 5 Ecology, safety and fire protect