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1、IssueDescriptors: Valves-TPS, ASME B31.3 PipingTechnical Purchase SpecificationValvesASME B31.3 Process PipingOrig.:Checked:Appr.:Total 8 PagesReplacesIssue 11.99eag1 1 2 2 2 p 3 二二eag1 1 2 2 2 p 3 二二ContentsScopeApplicable Codes, StandardsAdditional RequirementsDesignReview of Manufacturers Documen

2、ts355577788355577788WeldingPostweld Heat Treatment (PWHT)Surface FinishTestingMarkingCleaning, Coating and PackingInspectionDelivery notesCertification1 ScopeThis specification covers valves including control valves of steels, nickel alloys and aluminium alloys for use in process piping according to

3、 ASME code B31.3. It also applies to monoblock T- and Y-strainers.This specification does not apply to safety valves, rupture discs, pressure-, level- or temperature-gauges or similar items.In case of contradictions, the documents shall apply in the decreasing order of priority as follows:Purchase O

4、rder (P.O.);Material Requisition (M.R.) with purchasers valve specification and purchasers valve drawings; andThis specification 031-6XX.The word valve1, be in singular or in plural, hereinafter is synonymous with all items falling within the scope of this specification as described above.2 Applicab

5、le Codes, StandardsThe following codes, standards and specifications shall be applied besides those mentioned in P.O./M.R. Issues and addenda valid at the time of placement of order shall govern.ASME B31.3ASME B16.5ASME B 16.25ASME B16.34ASME B 16.47API Standard 598API Standard 600API Standard 602MS

6、S SP-9MSS SP-25MSS SP-55Linde Standard 001-02Linde Standard 141-74Process Piping (with all Standards and Specifications thereof)Pipe Flanges and Flanged FittingsButtwelding EndsValves - Flanged, Threaded and Welding EndLarge diameter Steel Flanges, NPS 26 Through NPS 60Valve Inspection and TestingSt

7、eel Gate Valves, Flanged and Buttwelding EndsCompact Carbon Steel Gate ValvesSpot Facing for Bronze, Iron and Steel FlangesStandard Marking System for Valves, Fittings, Flanges and UnionsQuality Standards for Steel Castings for Valves, Flanges and Fittings and other PipingComponents - Visual MethodI

8、nspection DocumentsAir Separation Plants, Surface Cleanliness3 Additional Requirements3-1 Design3.1.1 Thickness: Minimum thickness of the valve body shall as a rule be according to ASME B16.34 for standard class. For NPS beyond the limits of ASME B16.34, the method described in Annex F of ASME B16.3

9、4 shall apply with due consideration and observance of additional thickness referred to in paragraphs F1.3 and F1.4 of the annex for the determination of the minimum body wall thickness. Exception to the above are:For compact design check-, gate- or globe- valves of class 800 and below, the minimum

10、valve body thickness shall be as per API 602; andFor compact design gate valves above class 800 the minimum valve body thickness shall be as per API 600 for all materials and pressure-temperature rating shall be as per ASME B16.5.Any deviation from specified face-to-face and end-to-end dimensions re

11、quire prior express approval from the purchaser.Unless otherwise specified, all valves shall be of full-bore type with a flow passage diameter not less than 90% of the inside diameter at the valve end. This requirement does not apply to control valves.The valves shall be so designed that in the vert

12、ical or inclined position the hand wheel can be dismantled with the valve in open position without the stem and the closure part falling into the seat.The guiding system for the gate of gate valves shall have a minimum clearance and an overlap of at least 30% of NPS in the fully-open position so as

13、to enable the installation of the valve in any position.Wear travel for gate valves shall as per Table 1.Table 1 - Minimum Wear TravelSizeMinimum Wear TravelNPS up to and including 24NPS above 24 and up to and including 32NPS above 32 and up to and including 48according to API 60013 mm18 mmIn case o

14、f unidirectional flow valves, the design must be such that after disassembly a wrong reassembly of the closure part is not possible.The open and closed positions shall be clearly shown in case of butterfly valves and plug/ball valves, also when the operating devices like hand lever, hand wheel, gear

15、 drives have been dismantled. In case of multi-passage valves the selected flow direction must be clearly discernable, whether or not the drive unit is in position or is disassembled (not applicable to pneumatically operated valves).Threading in cast iron for stud bolts is not permissible.Review of

16、Manufacturers DocumentsThe purchaser shall be furnished for purposes of review/approval by the valve supplier/ manufacturer along with the offer, or latest before commencement of manufacture, (a) invariably with assembly drawings plus material lists (and welding procedure qualifications in case of w

17、elded valves) and (b) if required, with strength calculations.MaterialsDeviations from the materials specified require prior express consent of the purchaser.For valves of NPS 2 or less forged material shall be used for the body. However, investment castings are permissible for ball valves for water

18、, air or nitrogen.Heat analysis of C-steel valves either welded or with welding ends: Maximum carbon content shall be 0,25 % or as per material specification, whichever is lower.The material for the stuffing box flange shall be same as or similar to that of the valve body, or at least meet all the r

19、equirements set for the valve body.The packings shall be non-corrosive and in case of valves in oxygen service shall be free from any corrosion inhibitors.All gaskets and stuffing box packings shall be asbestos-free.Material imperfections and leakage shall not be repaired by peening, plugging, cemen

20、ting or sealing.In case of valves NPS 20 and above or having a minimum valve body thickness of 25 mm and more repairing defective materials by means of welding for repair depths of more than 40% of the wall thickness always requires prior express approval of the purchaser.In order to speed up the pu

21、rchasers decision application for approval shall contain the following minimum information:description of the defect(s),proposed method of defect removal,proposed nondestructive examination (NDE) after defect removal to ensure total removal of the defect(s),welding procedure specifications (WPS) alo

22、ng with the supporting welding procedure qualification records (PQR),proposed NDE after repairs to confirm the soundness of the repairs,any required subsequent heat treatments/NDEwhether or not pressure tests are repeated.Special attention is drawn to ASME B31.3, rule 323.2.2 as regards impact testi

23、ng requirements for materials for service below the minimum temperatures permitted by the code.For all non-metallic components for valves in oxygen service (see valve specification) certification from a reputed and independent testing laboratory, e.g., Bundesanstalt fur Materialprufung (Federal Inst

24、itue for Material Testing), Berlin, shall be furnished confirming their suitability for the specified oxygen service conditions.Austenitic stainless steel materials shall be delivered in a final solution heat treated condition.Cold drawn ASTM B 407 N08800 pipes for welded construction (see 3.4.1 bel

25、ow) shall be in a final condition after annealing at about 985 (1800F).In case of ERW pipes of ferritic steels for welded construction (see 3.4.1 below) suitable heat treatment such as normalizing shall be applied so that no untempered Martensite is present.All items made out of nickel alloys shall

26、be in suitably annealed “ condition.ASTM A 193 Grade B7 bolts shall not be used for design temperatures below -40 down to -46 unless they are in a final quenched and tempered condition.In case of ASTM A 193 and A 320 for Class 2 bolts the maximum hardness shall be Rockwell C35 immediately under the

27、thread roots. The hardness shall be taken on a flat area at least 3 mm across, prepared by removing the threads. No more material than necessary shall be removed to prepare the area. Hardness determination shall be made at the same frequency as tensile tests.ASTM A 194 Grade 7 nuts for use with ASTM

28、 A 320 Grade L7 bolts shall not be used for design temperatures below -46 down to -101 unless they are impact tested in accordance with ASTM A 320.ASTM A 320 Grade L7 + S3 bolts (size 2 inches and 13% Cr) are not permissible in the valve design. This requirement does not cover casting repairs at the

29、 foundry. Nevertheless 3.3.8 and 3.4.6 above are applicable.Postweld Heat Treatment (PWHT)PWHT for the welds of welded valves (see 3.4.1 above) shall be conducted as per the requirements of ASME B31.3 taking into consideration all requirements for any exemptions. Salient features are shown in Table

30、2 for ready reference.Table 2 - PWHT RequirementsMaterialP-NumberAnalysis RestrictionsSpecified Minimum Tensile StrengthpsiNominal Wall ThicknessmmHolding TemperatureHolding Time (The higher of the following applies.)Hour(s) minimumHour(s) per (inch ) 25 mmCarbon SteelsP-No.1noneall 19593-64911Alloy

31、 SteelsP-No.3Cr 1/2%71000 16 all593-64911Alloy SteelsP-No.41/2 % Cr2%71000 13 all704-74621Alloy Steels2 1/4%Cr10%P-No.5Cr3%&C 13 all704-76021Ni-Alloy SteelsP-No.9noneall 19593-63511Surface FinishAll castings shall be properly cleaned free from sand, foundry scales, scabs etcFlange back shall be spot

32、 faced for nuts as per MSS SP-9.Examination and TestingMaterial testing shall be in full compliance with the applicable ASTM material specifications as well as this specification certified material test reports are required for pressure loaded parts excepting bolting.See also 4 below.Nondestructive

33、Examinations(NDE)MaterialsNondestructive Examinations(NDE) shall be conducted as per Table 3 on each cast valve body of butt welding end type over a length of 50 mm from the welding ends. In case of valves with pipe extensions the pipe ends are excluded from these NDEs.Table 3 - Nondestructive Exami

34、nation of Valve Body CastingsUnmachined Thickness at Welding End TMaterialNondestructive ExaminationT 38 mmAllRadiography (RT)38 mm T 19 mmAllNon-magnetic materials: Liquid Penetrant Exam.(PT) Magnetic materials: Magnetic Particle Exam. (MT)T 19 mmP-No. 4 and 5Magnetic Particle Examination (MT)T 19

35、mmAll but P-No. 4 and 5noneIrrespective of the material each valve body casting having a minimum cast thickness of 19 mm or more in the valve body (excluding flanges in case of flanged valves) shall be subjected to an initial (prototype) radiographic examination after initially finalizing the foundr

36、y techniques as regards pouring, running, feeding, etc. All such locations in the valve body where the casting wall thickness is 150 % or more of the minimum valve body thickness shall be radiographed so that casting defects such as shrinkage porosity, cracks etc. can be consistently ruled out in pr

37、oduction batches later.The proof hereof shall be submitted by the supplier to the purchaser at the time of placement of the purchase order and shall also be included in the final certification for the valves. In the absence of such established evidence at least one casting per each type of such valv

38、es out of the supplies shall be radiographed.All cast valve bodies and cast bonnets shall be visually examined all over the surfaces in accordance with MSS SP-55.Additional material in the form of lugs or collars which are required for performing pressure tests shall be removed by machining after su

39、ccessful pressure tests and all such freshly exposed surfaces shall be subjected to liquid penetrant examination.WeldsAll welds shall be visually examined.All pressure loaded full penetration welds in the main body / external pressure envelope (see 3.4.2 above) of valves of welded construction (see

40、3.4.1 above) shall be subjected to 100% radiography for longitudinal welds and 10% random for circumferential seams including all weld intersections.All pressure loaded fillet welds in valves of welded construction (see 3.4.1 above) shall be subjected to a 10% random liquid penetrant examination. 10

41、% random means all such welds in one valve out of a lot of 10 valves or fraction thereof shall be 100% examined. (Example: 3 valves tested out of total 24 valves.)All weld-repaired locations of materials shall be subjected to NDE as follows ( See 3.3.5. No repairs to be undertaken without purchasers

42、 consent.) : Radiography (RT) for repair depth of 6 mm or more and liquid penetrant examination (PT) for repair depth less than 6 mm.Radiography of alloy steel class 22 pipes of ASTM A 672 and ASTM A 691 used for welded construction (see 3.4.1 above) shall be conducted only after completion of all n

43、ecessary heat treatments including postweld stress relieving heat treatment.All welds in fittings welded with filler metal used for welded construction (see 3.4.1 above) shall be radiographed over the entire length . Ultrasonic examination is not permitted as a substitute for radiographic examinatio

44、n.Special Class Valves shall be subjected to all examinations as per para. 8 of ASME B16.34 in addition to all the above mentioned examinations.Testing methods including evaluation shall be in accordance with the applicable Annex of ASME B16.34.Pressure and Leak TestsAll pressure tests and leak test

45、s shall be conducted only after completion of the required welding and heat treatments.Pressure tests shall be conducted in accordance with API 598 unless otherwise specified.Leak Tests: Maximum permissible leakage rates for all valves except non-return valves shall be as perTable 4.Table 4 - Maximu

46、m Permissible Leakage RatesNPSTest Medium and Maximum Permissible Leakage Rateaboveup to and includingAir - Bubbles / minuteFluid - Drops / minute-2000204010404821Wall Thickness Check: The valve manufacturer shall check the valve body thickness at all critical locations and several other important l

47、ocations and ensure that the body minimum thickness is maintained.ASTM B 407 seamless pipes and ASTM B 514 welded pipes used for welded construction (see 3.4.1 above) require hydrostatic test as per material specification. A final pressure test of the welded construction can be considered as an alte

48、rnative.MarkingThe markings shall be durable and legible and shall be applied on the body to the maximum extent possible and if necessary on a plate of stainless steel or aluminium permanently attached to the valve body. The valve ident number shall always be stamped in the valve body.All valves exc

49、ept Control ValvesAll markings required by MSS-SP-25Valve Ident.numberPurchase Order NumberControl ValvesAll markings listed in Table 1, IEC 534Valve (Item-)ldent. number (See purchase order)Purchase Order numberTag numberRating plate in case of valves with automatic operation and control equipmentA

50、ll valves in Oxygen ServiceAs for 3.8.1 or 3.8.2, as applicable“ free from oil and grease”Cleaning, Coating and PackingIn general, the valves shall be supplied in a clean and dry condition free from foreign matter like dirt, metal chips etc. Stainless steel parts shall have a bright finish.All outer

51、 surfaces of ferritic valves excepting flange facings, stem and buttwelding ends up to a distance of 10 mm from the ends shall after proper descaling and degreasing be given a primer coating as per manufacturers standard practices, unless otherwise specified.Such unpainted areas as well as the inner

52、 surfaces of above valves shall be treated for adequate protection against corrosion. The protective agent shall be suitable for oxygen service in case of such valves. Information concerning the removal of coating shall be furnished by the supplier.All openings up to NPS 12 shall be closed with plas

53、tic covers and larger ones with plastic foil and wooden cover. Stems shall be protected against damages during transport, e.g., with plastic sleeves.Valves with specific cleanliness requirements (e.g., oxygen service) shall be diligently cleaned and properly packed for retention of cleanliness during transport.The valves shall be supplied in closed position. Valves with control