02. Piping systems_general_2012 [Compatibility Mode].pdf

02 Piping systems- generalGeneral requirements, certification, NDT, testing

Course No. 2004

Det Norske Veritas AS. All rights reserved Slide 220 May 2013

Piping defined in Pt.4 Ch.1 Sec.1 B

Pipes

Flanges with gaskets and bolts and other pipe connections

Expansion elements

Valves, including hydraulic and pneumatic actuator, and fittings

Hangers and supports

Flexible hoses

Pump housing

General Piping System Requirements


System drawings layout Pt.4 Ch.6 Sec.1 C 103 The plans shall be diagrammatic, and shall include the following particulars: outside diameters and wall thicknesses of pipes materials used in pipes, valve bodies and fittings pump type and capacity type of valves and fittings type of expansion elements maximum working pressure, if exceeding 7 bar, and temperature if exceeding 60C hydrostatic test pressure after installation on board.For plastic pipes shown in system drawings the following information shall be given: fire endurance class conductive or non-conductive grade maximum working pressure and temperature, test pressure with duration.


Pipe classes

Pt.4 Ch.6 Sec.1 Table B1

Pipe classes are used for determining: Material requirements, Material certification, Product certification, NDT

requirements, Hydrostatic test, Type of different detachable pipe connections(flange), Application of slip-on sleeve joint etc..

More strict requirements

Less strict requirements


Pipe thickness

Pt.4 Ch.6 Sec.6 - For normal low pressure applications Tables A1 to A3 to be used

- Table A1: Copper and copper alloys- Table A2: Steel pipes- Table A3: Stainless steel pipes

- For hydraulic system and other high pressure systems the pipe thickness formula to be used


Pipe thickness



External Diameter D(mm) Minimum wall thickness (mm)10.2 to 17.2 1.021.3 to 48.3 1.660.3 to 88.9 2.0

114.3 to 168.3 2.3219.1 2.6273 2.9

323.9 to 406.4 3.6over 406.4 4.0

Note:The external diameters and thickness have been selected fromISO-Standard 1127. For pipes covered by other standards,thickness slightly less may be accepted.

Minimum wall thickness (mm)External Diameter D(mm) Copper Copper alloy

D 10 1 0.810 < D 20 1.2 1

20 < D 44,5 1.5 1.244,5 < D 76,1 2 1.576,1 < D 108 2.5 2108 < D 159 3 2.5159 < D 267 3.5 3267 < D 470 4 3.5470 < D 508 4.5 4

Table A3 Minimum wall thickness for stainless steel pipes

Table A1 Minimum wall thickness for pipes ofcopper and copper alloy



Air pipes above deck (Pt.3 Ch.3 Sec.6 I304)

For intermediate external diameter the wall thickness isobtained by linear interpolation

External diameter Wall thicknessin mm in mm

< 80 6.0> 165 8.5


< 155 4.5> 230 6.0

Scupper and sanitary discharge pipesinboard of closable valve (Pt.3 Ch.3 Sec.6 K202) :


< 80 7.0= 180 10.0> 220 12.5

Hull distance pieces (Pt.3 Ch.3 Sec.6 K201) :

Scrubber distance piece 15mm or shell platethickness, whichever is higher

hAdditional pipe wall thickness

Shipside pipes


Pipe thickness calculation

Corrosion allowance, depending on pipe material/service

Values for the material used can be found in tables for standard materials


Pipe thickness calculation


Example

Hydraulic pipes

Material St.35

Max. pressure 280 bar Pipe dimensions: 16 x 2, 20 x 2,5, 30 X 3, 38 x 4, 65 x 8 (mm) Find t : St.35 : tensile = 340 N/mm2 ; yield 0,2% = 235 N/mm2

t = lowest of 340/2,7 or 235/1,6 = 126 N/mm2

e = 1 (seamless pipes)

t0 = 28012620280

20 +

=

+

Dpe

pD

t


Result of calculation

D x t t0 Rule minimum

t = t0 + c

16 x 2 1,6 1,9

20 x 2,5 2,0 2,3

30 x 3 3,0 3,3

38 x 4 3,8 4,1

65 x 8 6,5 6,9


Conclusion

The pipes with outer diameter 30mm and 38 mm must be changed


Pipe thickness

Case 1

1) What is minimum acceptable thickness for a hydraulic pipe:Maximum pressure: 280 bar

Outer diameter: 38 mm

Material: Austenitic AISI 316: (b)tensile = 500N/mm2

(ft)yield0,2% = 220 N/mm2

2) What is minimum required thickness for a steel air pipe with outer diameter 88,9 mm?

3) What is minimum required thickness for a CuNiFer pipe with outer diameter 76,1 mm?


Detachable Pipe Connections

Flange connections

Pipe couplings other than flanges

Expansion bellows


What is PN and DN? PN (Pressure nominal) is the rating designator followed by a designation

number, which indicates the approximate pressure rating in bars.

DN (Diameter nominal) is a dimensionless designator of pipe size in the metric unit system, developed by the International Standards Organization (ISO).It indicates standard pipe size when followed by the specific size

designation number without a millimeter symbol.


Flange connections

Flange connections

- Flanges with their pressure-temperature ratings in accordance with a recognized national standard will be normally be accepted

- Examples of accepted flange connections for steel piping

- Typical applications of these types of connections are given in Table E1 depending upon the class of piping, media, size, pressure and temperature.

- Other types of flange connections will be considered in each particular case.


Flange connections


Types of flanges

1. Slip-On flanges

2. Lap Joint

3. Welding neck flanges

4. Blind flanges

5. Socket welding flanges


Slip-on Flanges

The Slip-on flanges has a low hub because the pipe slips into the flanges prior to welding. It is welded both inside and out to provide sufficient strength and prevent leakage. Slip-on flanges are all bored slightly larger than the O.D. of the matching pipe They are preferred over welding neck flanges by many users due to their lower initial cost, but final installation cost is probably not much less than that of the welding neck flange because of the additional welding involved.

Slip-on Flanges

Welding

Pipe


Lap Joint Flanges

The lap joint flanges is practically identical to a slip-on flange except it has a radius at the intersection of the bore and flange face. This radius is necessary to have the flange accommodate a lap joint stub end. Normally, a lap joint flange and a lap joint stub end are mated together in an assembly system.

Stub end


Welding Neck Flanges The welding neck flange is normally referred to as the

"high hub flange. It is designed to transfer stresses tothe pipe, there by reducing high stress concentrationsat the base of the flange. The welding neck flange isthe best designed butt-welded flange of those currentlyavailable because of its inherent structural value. It isexpensive because of the designed

Welding Neck Flanges

Pipe

Welding


Socket Welding Flanges The socket welding flange is similar to a slip-on flange except it has a bore and a counter

bore dimension. The counter bore is slightly larger than the O.D. of the matching pipe, allowing the pipe to be inserted into the flange similar to a slip-on flange. The diameter of the smaller bore is the same as the I.D. of the matching pipe.A restriction is built into the bottom of the bore which sets as a shoulder for the pipe to rest on. This eliminates any restriction in flow when using a socket welding flange.

Pipe

Welding


Blind Flanges The blind flange is a flange without a bore. It is used to

close off the ends of a piping system and/or a pressurevessel opening. It also permits easy access to the interior of a line or vessel once it has been sealed andmust be reopened.

Blind Flanges


TYPES OF FLANGE FACING

1. Flat Face

2. Raised Face


Flange Facing Types

The flat face variety allows the matching flanges to be in full face contact with the gasket clamped between them. This construction is commonly used in low pressure, cast iron and brass valves and minimizes flange stresses caused by initial bolting-up force.

The raised face flange features a circularraised face with inside diameter the same as the valve opening and with the outside diameter something less than the bolt circle diameter. Theraised face is finished with concentric circular grooves for good sealing and resistance to gasket blowout. This style of flanging is normally standard on steel and alloy steel bodies.

GASKET

Used for pipe flanges delivering fluids such as steam, water and oil.

1. Flat Nom-Metallie and Metal Clad or Jacketed Gaskets

2. Spiral Wound Gaskets

3. Flat Metal Gaskets

4. Ring Joint

5. Oval Ring Joint

GASKET


Pipe couplings other than flanges Mechanical Joints- Pipe unions- Swage type- Press type- Bite type- Flared type- Dresser coupling- Sleeve type coupling


Pipe couplings other than flanges Mechanical Joints including pipe unions, compression couplings, slip-on joints and similar

joints shall be Type Approved for the service conditions and the intended application.

Examples of mechanical joints

Pipe Unions - Welded and Brazed type


Pipe couplings other than flanges Examples of mechanical joints

Swage type Press type

Flared type



Examples of mechanical joints (Bite type)

Brass SUS



Examples of mechanical joints

Dresser coupling Sleeve type coupling


Application of mechanical joints

Footnotes:2) Not inside machinery spaces of category A or accommodation spaces. May be

accepted in other machinery spaces provided the joints are located in easily visible and accessible positions.

3) Approved fire resistant types5) In pump rooms and open decks - only approved fire resistant types

Table E3, Pt.4 Ch.6 Sec.6



Footnotes:1) Inside machinery spaces of category A - only approved fire resistant types3) Approved fire resistant types4) Above free board deck only



Abbreviations:+ Application is allowed Application is not allowed

Footnotes:2) Not inside machinery spaces of category A or accommodation spaces. May be

accepted in other machinery spaces provided the joints are located in easily visible and accessible positions.

3) Approved fire resistant types


Application of mechanical joints depending upon pipe classTable E4 Pt.4 Ch.6 Sec.6


Socket Welded Joints and Slip-on Sleeve Welded Joints

Socket welded joints and slip-on sleeve welded joints - used for class I and II pipes with O.D 88.9 mm and less.- used for class III pipes.- not be used in overboard pipes where substantial thickness is required.

Joint designs and socket dimensions in accordance with a recognized national standard

Socket welded joints and slip-on sleeve welded joints in stainless steel pipes will be subject to the Society's consideration in each case. Problem: Crevice corrosion and pitting.


Flexible hoses

h Not used for- Bilge systems- Ballast systems

hFlexible hoses (Pt.4 Ch.6 Sec.6 D)

h Short lengthh Type approved with couplingh Every hose hydrostatic tested to 1.5 times working pressure

h Means are to be provided to isolate flexible hoses used in the following systems:

- Fuel oil- Lube oil- Sea water cooling- Compressed air


Valve

A valve is a device attached to a pipe or a tube which controls the flow of air or liquid through the pipe or tube.

Valves are provided in a piping system to regulate or stop the liquid flow.

Various types exist with their associate particular function or advantages.


Valve

Pressure- temperature rating according to a recognized national standard

Screwed-on valve bonnets normally not accepted for class I piping above DN40, or for ship side or bottom valves or valves in flammable systems (Exemption: Ship side valves to JIS standard with stainless steel locking pin are normally accepted- rules will be updated to reflect this)

Screwed-on valve bonnets to be secured against loosening at operation

Indication to show the open and closed position of the valve

Welding necks of valves to be long enough to avoid the valve being distorted by welding/ heat treatment

Pt.4 Ch.6 Sec.7 C


Ship side valves

Ship side valves: It shall be possible to disconnect piping inboard of the valve without interfering with shell integrity e.g. should be separate double flanged or lug type, not wafer type (wafer type means a common bolt is used).


Flange TypeLug Type Wafer Type

Not hole through


Marking on valve body

DIN : DN100 : NDPN16 : PN : Flow directionGS-C25N : Body material

DIN : German Institute for Standardization



JIS : 20K-65 : PN-DNSC : Body material : Flow direction

JIS : Japanese Industrial Standards



ASME: 4 : DN (Inch)WCB : Body material

150 : Class #

ASME : American Society of Mechanical Engineering


STRUCTURE OF VALVE

BODY SEAT RING

BODY

STEM

HAND WHEELNAME PLATE

DISC

BONNET

DISC NUT

YOKE SLEEVE

PACKINGPACKING RING


STRAIGHT ANGLE

GLOBE /ANGLE VALVE - A glove valve has a somewhat spherical body enclosing the valve seat and valve disc. - The valve disc and seat are a prefect match and may be flat or, more commonly, mitred.- Glove valves exist in a straight or right-angled form where the inlet and exit flanges are

at 90 to each other.


GATE VALVE

- A gate valve should be fully open or closed. (it is not suitable for flow control)

- When open it provides a clear full-bore internal passage for the liquid since the valve or gate is raised clear.

- The gate may be parallel or wedge-shaped in section fitting against a matching seat.


BUTTERFLY VALVE

A butterfly valve is a type of flow control device, typically used to regulate a fluid flowing through a section of pipe.

The plate has a rod through it connected to a handle on the outside of the valve. Rotating the handle turns the plate either parallel or perpendicular to the flow.


BUTTERFLY VALVE

Flange TypeLug Type Wafer Type


BUTTERFLY VALVE

Eccentric Type Concentric Type

- Concentric Type- Eccentric Type- Double eccentric Type


BUTTERFLY VALVE

Double-eccentric type


CLOSE OPEN

BALL VALVE (2-WAY) which is good for on/off control.


BALL VALVE (3-WAY)

L-Type T-Type


NEEDLE VALVE

Normally, this valve is used for small tubing for instrumentation such as root valve for pressure gauge, transmitter and switches


CHECK VALVE

Chest valve or Non-return valve, allows the fluid to pass in one direction only.

Protection of any item of equipment that can be affected by reverse flow, such as flow meters, strainers and control valves.

Prevention of flooding, reverse flow on system shutdown an flow under gravity.

Screw Down Non Return Valve


CHECK VALVE

Folding-disc check valve

Swing check valve


STORM VALVE

Used in scuppers and sanitary discharges as closing appliances. Set in the annulus between the drill pipe and the well casing, the actuator

being designed to close the valve upon initial axial movement of the upper portion of the drill pipe

Become disengaged from the lower portion of the set drill pipe allowing the remaining surface suspended drill pipe and actuator to be retrieved as in the case of a floating drill ship or set aside for reconnection and reopening of the storm valve after a storm has passed.


STORM VALVE

Angle TypeVertical Type


QUICK CLOSING VALVE Oil tank suction valves are arranged for

rapid closing from a remote point by the use of quick-closing valves.

Mechanically kept open, usually hydraulic or pneumatic system to remove the mechanical lock, spring closed


HOSE VALVE Hose valves have heavy rough brass body with machined brass vandal-resistant lock shield

bonnet and are furnished with a removable wheel handle. Hose valve covering helps prevent damage to delicate tank or vessel linings, machines,

floors, and protects the valve. Innovative ball-and-seat design provides a tight shut-off to minimize leakage.


HOSE VALVE


COCK

Colloquial term for a small valve.


RELIEF VALVE

Safety valves and pressure-relief valves are automatic pressure-relieving devices used for overpressure protection of piping and equipment. Safety valves are generally used in gas or vaporservice because their opening and reseating characteristics are commensurate with the properties and potential hazards of compressible fluids. The valves protect the system by releasing excess pressure.Pressure-relief valves are used primarily in liquid service. These valves function in a way similar to safety-relief valves, except that as liquids do not expand, there is no additional lifting force on the disc and, therefore, the valve lift is proportional to the system pressure. Also, the valves reseat when the pressure is reduced below the set pressure.


RELIEF VALVE


REGULATING VALVE

Pressure Regulating Valve This valve is provided with a piston chamber at its actuator section. The inlet pressure is conducted to the lower side of the piston.

The object of this valve is inlet pressure regulation involving control of the inlet pressure of the valve.

This valve is used as a back pressure valve.


THERMOSTATIC VALVE

By-pass Outlet

Inlet(Source: atom controls)


Certification

Material certification (DNV (NV) certificate, works certificate, or test report) Product certification: DNV product certificate for each specific component

- In piping systems may be relevant for: Valves, pumps, pressure vessels

Type approval certification: Certificate for a component design, not for each specific component

- Product certification may in some cases still be needed for a product with type approval certificate (e.g. engines)

- Type approval required for flexible hoses, mechanical joints (not flanges). For bellows type approval or case approval.


Material certification

Same scopeTesting done for

the product itself

Testing done on similar product, but not the exact same


Material certification

Material certification: Pt.4 Ch.6 Sec.2 Table A2


Material requirements

Pt.4 Ch.6 Sec.2

Different requirements for different pipe classes

Note the limitations for use of grey cast iron in class I and II systems and in class III fuel oil valves on tanks and on ship side/ collision bulkhead valves

Fire endurance matrix for plastic pipes in Table A1 limits the use of materials with bad fire endurance properties

Note general material requirement in Pt.2 Ch.2 stating that materials with NV or works certificate shall come from DNV certified material works


Fire endurance matrix- plastic pipes


Product certification - pumps

Certification of pumps: Pt.4 Ch.6 Sec.6 B100


Product certification- pumps

Pump certification requirements in Pt.4 Ch.6 Sec.6 B300 and B400:- Hydrostatic tests- Capacity tests


Valve certification: Pt.4 Ch.6 Sec.6 C300

Product certification- valves


Product Certificates


Testing of valves

Valve bodies: Hydrostatic test to 1,5 times maximum allowable working pressure by manufacturer

- Ship side valve: Tested to not less than 5 bar

Butterfly valve for ship side/ bottom: - Also hydrostatic tested at a pressure equal to 5 bar applied independently on

each side of the closed disc

Same testing regardless of requirement for NV product certificate difference is DNV surveyor presence and who writes the certificate


Piping systems general

Case 2

1) What is the pipe class for steam piping system with design pressure p= 24 bar, t = 200 bar?

2) What kind of material certification is required for a DN80 steel valve body in this system?

3) And what kind of material certification is required for a DN80 pipe in this system?

4) Is DNV product certificate required for a DN80 valve?


Section 7

Manufacture, workmanship, inspection and testing

For drawing approval we need to verify hydrostatic test pressure- Depending on pipe class and medium

NDT mainly relevant for PM, but we may be asked for advice



h Functional testing ;

All piping systems are to be

1. Properly flushed

2. Checked for leakage

3. Functional tested under working conditions

To the satisfaction of the attending surveyor


Non-destructive testing Butt welded joints:

For class I pipes with O.D > 76.1 mm, 100% RT (radiographic testing) is required.For class II pipes with O.D > 101.6 mm and

For class I pipes with O.D 76.1 mm, as least 10% random RT is required

* More stringent requirements may be applied at the surveyors discretion depending on the kind of materials, welding procedure and controls during the fabrication


Non-destructive testing Fillet welds:

For fillet welds of flange type connections in class I pipes with OD > 76.1 mm, 100% MT(magnetic particle testing) is required.For class II pipes with an OD > 101.6 mm and

For class I pipes with and OD 76.1 mm, random MT at the discretion of the surveyor is required.

In additional welded joints in pipes for thermal oil shall be subject to at least 10% random RT.


Non-destructive testing of heating coils

1) If automatic welding is used, the percentage may be reduced at the surveyors discretion

2) Experience shows that pressure tests do not always reveal leaks in joint because a capillary gap can be temporarily sealed by flux residues. A recommended part of the precedure for testing a heating coil system should therefore be to apply a steam test, which will dissolve flux residues and reveal leaks.

Material in coils

Joint types

Butt welds 1) Sleeve or lap welded or brazed joints

Erection welds Shop welds Election joint

Shop welded or brazed joints

Mild steel 10% 5% 10% 5%

Stainless steel 10% 5% 10% 5%

Cu-Ni or Al-brass 10% 5% Spot-check NDT. Steam testing onboard

2)

Table A4 Pt.4 Ch.6 Sec.7


Nondestructive test Visual Inspection (VI) Dye Penetration Test (PT), Liquid Penetrating Test Magnetic Particle Inspection (MT) Ultrasonic Testing (UT) Radiographic Testing (RT)


Visual Inspection (VI)Method: The test object is subjected to examination by the experienced eye of an inspector assisted by viewing aids and measuring gauge.Application/advantage: The method may be used on all objects-cast, rolled and welded. Visual inspection before, during and after welding may be detect an aid in the elimination of discontinuities that might become defects in the final welding


Dye Penetration Test (PT)

MethodThe surface to be examined is covered with liquid that penetrates surface open cracks. The liquid in cracks bleeds out to stain powder coating to the surface after removal of excess liquid film from the surface of the test object.

Application/advantagePT is sensitive method to detect defects like cracks and pores that are open to the surface of the material. PT may be used on both ferromagnetic and non-ferromagnetic material.


Dye Penetration Test (PT)???????????? ????????????

???????? ????


Magnetic Test (MT)

MethodWhen an object is magnetized, iron powder applied to the surface will accumulate over regions where the magnetic field is disturbed as a result of surface flaws.

Application/advantageThe MT is applicable only to ferromagnetic materials. It is for example not applicable to stainless weld deposit on ferromagnetic base material. Trained operators are necessary to avoid misinterpretations.


Magnetic Test (MT)

Magnetic particle wet fluorescent indication of a crack at a sharp radius.

Magnetic particle wet fluorescent indication of a crack in a bearing.

From www.ndt-ed.org


Ultrasonic Test (UT)

Method: Ultrasonic pulses are directed into a test object. Echoes and reflections indicate presence, absence, and location of flaws, interfaces, and/or defects

Application/advantages: Ultrasonic testing is a sensitive NDT-method, which can be used on metals or non-metals. Best results are obtained when the sound beam is perpendicular to the defect.Defects may be detectedAt depths ranging from 5 mm to 10 mm in steel.


Radiographic Test (RT)

Method: Radiographic image is produced by the passage of X-rays or gamma rays through the best object onto a film.Application/advantage: Radiographic test can be used on all metals to detect defects with an appreciable dimension parallel to the radiation beam, on or below the surface of the object. Radiographic testing can be used on material thickness up to 100 mm Fe or more.


Piping systems general

Case 3

1) What is the pipe class of fuel oil piping with design pressure 9 bar

2) What is the NDT requirement for this piping?

3) What are the pressure testing requirements for this piping, before and after installation?

Documents

02. Piping systems_general_2012 [Compatibility Mode].pdf