SSeslija MR DAY 7_Plant Design.ppt

Mechanical Mechanical EngineeringEngineering

1A Vocational Degree programme developed by MCAST and Fraunhofer IAO.

Day 7Pressure Equipment Directive – PED

Pipelines


Pressure equipment directive (PED) 97/23/EC

The directive:- Design- Manufacturing and- Conformity assessment of pressure equipment

Products:- Pressure accumulators- Heat transducers- Steam boilers- Industrial pipelines- Safety devices (safety valves, shut-off devices, etc. - will be covered in a

separate section)- Auxiliary pressurized devices, flanges, nozzles, etc.

Industries:- Gas and oil industry- Pharmaceutical and chemical industry- Plastics industry - Food/beverage industry- High-temperature industry (manufacturing glass, paper, etc.)- Energy production- Gas storing and transport

Overview: slides 2 to 15


Group 1 comprises dangerous fluids. A dangerous fluid is a substance or preparation covered by the definitions in Council Directive 67/548/EEC - classification, packaging and labeling of dangerous substances.

Fluid groups – used for vessel/pipe classification

PED 97/23/EC

Group 1 comprises fluids defined as: — explosive, — extremely flammable, — highly flammable, — flammable (where the maximum allowable temperature is above flashpoint), — very toxic, — toxic, — oxidizing.

Group 2 comprises all other fluids not referred to in group 1.


Vessels

Gas (*) Liquid (**)

Fluid group 1 Fluid group 2 Fluid group 1 Fluid group 2

V > 1 LPS x V > 200 bar L

V > 1 L PS x V > 25 bar L

PS > 200 bar

Diagram 1 (Chart 1)

PSV

PSV

Diagram 2

PS > 500 bar

V > 1 LPS x V > 50 bar L

PS > 10 barPS x V >10000 bar L

PS > 1000 bar

Diagram 3

PSV

PS > 1000 bar

Diagram 4

PSV

CategoryCategoryCategoryCategory

or or or

(*) gases, liquefied gases, gases dissolved under pressure, vapours and also those liquids whose vapour pressure at the maximum allowable temperature is greater than 0,5 bar above normal atmospheric pressure, (1 013 mbar)

or

(**) liquids having a vapour pressure at the maximum allowable temperature of not more than 0,5 bar above normal atmospheric pressure, (1 013 mbar)


Fired or otherwise heated pressure equipment with the risk of overheating

Steam or super-heated water generators TS >110ºC i V >2 L Pressure cookers

Diagram 5

PSV

Category


Piping

Gas (*) Liquid (**)

Fluid group 1 Fluid group 2 Fluid group 1 Fluid group 2

DN > 25PS x DN > 2000 bar

DN > 25

Diagram 6

PSDN

Category Category

PSDN

Diagram 8

DN > 32PS x DN > 1000 bar

PS > 10 barDN > 200

PS x DN > 5000 bar

Diagram 7

PSDN

Category

Diagram 9

PSDN

Category

(*) gases, liquefied gases, gases dissolved under pressure, vapours and also those liquids whose vapour pressure at the maximum allowable temperature is greater than 0,5 bar above normal atmospheric pressure, (1 013 mbar)

(**) liquids having a vapour pressure at the maximum allowable temperature of not more than 0,5 bar above normal atmospheric pressure, (1 013 mbar)


PED 97/23/EC

- Gas group 1

Gas qroup 2 -

Similar form of

diagram

Example: PS = 10 bar, V = 80 L


PED 97/23/EC

gas liquid

different form

of diagrams

Example: PS = 10 bar, V = 80 L


PED 97/23/EC



PED 97/23/EC

Pressure equipment classification: according to ascending level of hazard(previously in numerous national standard - descending)

Category I = Module ACategory II = Module A1,

D1, E1

Category III = Modules B1 + D, B1 + F, B + E, B + C1, H

Category IV = Modules B + D, B + F, GH1

Low-hazard equipment – classified into a separate group – handled in accordance with Sound Engineering Practice. Such equipment is covered by directive SPVD-87/404/EC

CONFORMITY ASSESSMENT PROCEDURES


CONFORMITY ASSESSMENT PROCEDURES

PED 97/23/EC

Module A (internal production control)

Module A1 (internal manufacturing checks with

monitoring of the final assessment)

Module B (EC type-examination)

Module B1 (EC design-examination)

Module C1 (conformity to type)

Module D (production quality assurance)

Module D1 (production quality assurance)

Module E (product quality assurance)

Module E1 (product quality assurance)

Module F (product verification)

Module G (EC unit verification)

Module H (full quality assurance)

Module H1 (full quality assurance with design examination and special

surveillance of the final assessment)


Design and construction of pressure equipment – important factorsPED 97/23/EC

— internal/external pressure,

— ambient and operational temperatures,

— static pressure and mass of contents in operating and test conditions,

— traffic, wind, earthquake loading,

— reaction forces and moments which result from the supports, attachments, piping, etc.,

— corrosion and erosion, fatigue, etc.,

— decomposition of unstable fluids.

Various loadings which can occur at the same time must be considered,taking into account the probability of their simultaneous occurrence.

Safe handling and operationParticular attention must be paid, where appropriate, to: — closures and openings, — dangerous discharge of pressure relief blow-off, — devices to prevent physical access whilst pressure or a vacuum exists, — surface temperature taking into consideration the intended use, — decomposition of unstable fluids.


The conformity to the PED is ruled by the Harmonized Standards used as a benchmark. In Germany (and cont. part of Europe) the conformity to PED is alternately ruled by the AD 2000 Code, which is adapted to the Harmonized Standards and conservatively evolved from earlier AD Code.


The conformity to the PED is ruled by the Harmonized Standards used as a benchmark. In Germany (and cont. part of Europe) the conformity to PED is alternately ruled by the AD 2000 Code, which is adapted to the Harmonized Standards and conservatively evolved from earlier AD Code.


Main physical properties and structural requirements need to be taken into account during the design of pressure vessels (PV).

The calculation is for the parts of the PV that are made of low carbon non-alloyed, low alloyed and alloyed steel, cast steel, cast iron, copper, aluminum and their alloys. Calculation of smallest thickness / dimensions of vessel parts must result in prevention of plastic deformations and destruction / catastrophic failure of PV in exploitation.

The vessel or part of the vessel under gage pressure (in the remainder of the pres.: pressure),is calculated taking into account the design pressure that must not be lower than the highest pressure in the vessel during exploitation. When calculating a part of the vessel that is at the same time exposed to both externaland internal pressure, the calculation must be done separately for each of these pressures.

For vessels under vacuum, p = 1 bar

DESIGNING THE PRESSURE VESSELS - general requirements for calculations -

Design pressure


Design temperature

Design temperature is determined by the actual temperature of the material that is expected under operating conditions for the observed part of the vessel. If different temperatures of the material are expected for different parts of the vessel, then the calculation for these parts is performed using these temperatures. If the temperature of the wall of the structural part of the vessel shell is between -10 ◦C and 20◦C the calculation temperature is presumed to be +20 ◦C.

Strength

Strength of the vessel material will be determined depending on the design temperature.

In general, yield point value is accepted as the critical value:- yield strength σY or

- proof (conventional) strength σp0,2,(σp1.0 for more ductile materials, A > 30%)

depending on the shape of the stress-strain curve of the material.


If working conditions affect the strength dependence not only on temperature but also on service time, the appropriate critical strength is the lower value between the yield point and term strength after 100 000 hours of work (σB/100000) at known design temperature. It is also necessary to take into consideration the safety factor.

CRITICAL STRENGTH VDESIGN STR

SAENG

FETTH

Y

ALUE

FA =

CTOR ! !

Design strength (f in EN, K/S in AD Merkbl.)– calculated based on the critical strength – which shouldn’t be reached during the exploitation

Safety factor

values of safety factor in regard to the yield point are given in the next slide,that is, continuous time strength for most commonly used structural materialsfor making pressure vessels exposed to internal pressure.


Type of material Material safety factor at calculating

temperature (S)Material safety factor at

testing pressure (S')

Steel 1.5 1.1 (1.05) (*)

Cast Steel 2.0 (1.9) 1.5 (1.33)

Aluminum and aluminum alloys

1.5 1.1(1.05)

For vessels with external heating/cooling (double jacket or an outer half-pipe coil) -

it is necessary to take into account the effect of external pressure !! !!

Safety factor values

(*) following designation is used: AD Merkblaeter value (EN 13445 value) (if the two values are different)


This coefficient (ν, z) takes into account weakening of the pressure vessel structure due to:

- connecting of elements (referring to inseparable connections such as welding and soldering) - existence of openings in the individual elements of the vessel, needed to construct pipe connections, introduce stirrers into the vessel, etc.

To highlight the difference in the source of weakening coefficient values (AD Merkbl), the value that relates to the quality of the welded joint is marked with ν and the value related to the existence of an opening is marked with νA.

Weakening coefficient (AD Merkblaetter) - Joint coefficient (EN 13445)


Type of welds according to regul. used in Serbia

Example


For the calculation of required thickness of certain welded components (e.g. cylinders, cones and spheres),

design formulae contain z - the joint coefficient of the governing welded joint(s) of the component

Joint coefficient (EN 13445)

Examples of governing welded joints are:

- longitudinal or helical welds in a cylindrical shell;

- longitudinal welds in a conical shell;

- any main weld in a spherical shell/end;

- main welds in a dished end fabricated from two or more plates.

Types of welds according to EN


The following welded joints are not governing welded joints:

- circumferential weld between a cylindrical or conical shell and a cylinder, cone, flange or end other than hemispherical;

- welds attaching nozzles to shells;

- welds subjected exclusively to compressive stress.

z 1 0.85 0.7

Testing Group

1, 2 3 4

Joint coefficient and corresponding testing group

Joint coefficient (EN 13445) – contd.

For normal operating load cases, the value of z is given in following table.It is related to the testing group (allowed class) of the governing welded joints.

In parent (base) material, away from governing joints, z = 1. Testing groups are specified in EN 13445-5:2009, Clause 6.


Allowance c1 is for permissible deviation of measures of the material.

In the use of structural material that is not resistant to corrosion, allowance c1 is permissible negative deviation of measures (thickness)

according to the applicable standards for the accepted material. When using materials resistant to corrosion (primarily referring to austenitic stainless steels and non-ferrous metal alloys), it is often not necessary to take into account the negative measures tolerances.

Allowances

To ensure a minimum required calculated wall thickness of a structural element of the vessel, according to the required service life, allowances c1, c2 and c3 must be adopted - to take into account reduction in wall thickness c1, c2 and c3 - designations acc. to AD code – in EN: c and δ (figure will be shown later)

Allowance c2 is added to the computational wall thickness due to the reduction of the thickness of sheet metal by corrosion and wear. For ferrite steels - usually in the range of 1 - 1.5 mm, and for thicker walls (s ≥ 30 mm), it is not necessary to take it into account.


Allowance c2 can be omitted when the vessel walls are protected against effects of the

working medium, e.g. with rubber, textile, synthetic material coatings, etc.., but must be taken into account when applying metal coatings.

If the working medium is very corrosive, or if in latter use it will not be possible to view the interior of the vessel, a higher value of c2 (up to 3 mm) is adopted.

When using stainless steels (not only austenite) and non-ferrous metals, allowance c2 is

determined for each specific case; in general case c2 = 0.

Allowance c3 is added in case of brickwork lining, due to the additional stressesvalues of c3 are determined by the standards.


Thickness designations

The inter-relation of the various definitions of thickness

s se

EN 13445

c2

c1

s

ADcode

EN 13445AD

code


According to AD Merkbl.

Symbol

According to EN 13445Symbol

Outside diameter of cylindrical shell

Da De

Calculation pressure p P

Calculation temperature

T T

Coefficient of welded joint

ν z

Required thickness s e

Safety factor S S

Proof strength K ReH Rp0,2 Rp1,0

Nominal design stress K/S f

Distance between two reinforcements

l L

DESIGNATION COMPARISON

EN 13445

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SSeslija MR DAY 7_Plant Design.ppt