Hi Zhy,
There're many potential areas of pitfalls with many ifs and buts, the interpretations are a bit twisted. However it's worth taking a look.
Aramco Spec SAE W-012-2013 mandates:-
7.5 Welding Procedure Qualification Hardness Testing—This is required on the PQR .
7.5.1 Hardness testing of the welding procedure qualification is required for sour service applications and for girth welds of all offshore pipelines. The maximum allowable hardness for sour service is VHN 250.
13 Production Weld Hardness testing—when required?? If so what's the criteria?
13.1 Hardness testing according to ASTM A833 of production welds is only required if specified by CSD or if PWHT is applied due to service requirement. If specified, the maximum hardness for PNo. 1 material is 225 BHN for non-sour service and 200 BHN for sour service.
12 Post weld Heat Treatment
12.1 The requirement for post weld heat treatment (PWHT) shall be determined by ASME B31.4 or ASME B31.8, as appropriate.
12.6 For applications where PWHT is required by the service conditions or where hardness limits are specified: ---
a) Any reductions in the PWHT temperature or alternative temperatures below the normal holding temperatures listed in ASME SEC VIII are not permitted.
b) The minimum PWHT soak time shall be 1 hour.
c) If hardness limits are specified, the soak time for production welds shall not be less than 80% of the PQR soak time
ASME B-31.8 Requirements:
B823.2 Requirements for Qualification of Procedures and Welders on Sour Gas Piping Systems:-
B823.2.4 Hardness Control. The hardness of all weld zones including weld metal and heat-affected zones on welding qualification test specimens shall meet the hardness requirements for the alloys welded as specified in NACE MR0175/ISO 15156. For most common pipe alloys, the maximum allowable hardness is HRC22. It is the user's responsibility to ensure the welding qualification specimen is metallurgically representative of full-scale pipeline welds.
B825 STRESS RELIEVING –CARBON STEEL: The chemistry of the steel and welding procedure shall be controlled to limit the hardness of the weldment as required by para. B823.2.4. when the effectiveness of such controls is questionable, consideration shall be given to stress relieving welds in sour gas service. In general, temper bead welding, peening procedures, or low-temperature post weld heat treatment does not provide the equivalent protection from service cracking as does a full thermal stress relief.
To summarize:-
v Aramco spec restricts the hardness for sour service (Clause 7.5.1.)
v PWHT is s requirement weher hardness restrictions are mandated(Clause 12.6)
v B-31.8 ,mandates hardness control ,which is difficult maintain under field welding condictions, many variables,( pipe C.A, welding conditons,effectiveness of field hardness testing). The alternative is PWHT is all the above control fails in service.
Iwould interpret that PWHT should be an integral part of your FEED package for piping codes on B-31.8 for sour service requirements, based on the above rationales
For piping designed to B-31.4 PWHT is not a requirement unless the wall thickness exceeds 11/4 inch (32 mm)(Clause 434.8.9 Stress Relieving). However Armco Specification would call for an adopting PWHT due to hardness control where the service is sour.
I would say getting the clarification before hand from Aramco's PMT or CSD would be beneficial for your organization.
Thanks.
Pradip Goswami, P.Eng,IWE
Welding & Metallurgical Engineering Specialist ,
Ontario,Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299
H-905-6799677, 905-9631505
C-905-9793232
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of ???
Sent: Thursday, September 15, 2016 1:52 AM
To: materials-welding@googlegroups.com
Subject: Re: [MW:25396] RE: 25392] PWHT
Dear pgoswami:
Thank you for your reply!
PIPELINE design code is B-31.4/31.8 , Aramco specifications is SAES-W-012 and design office is SNC- lavalin
the pipeline is LSPB contract and in bidding phase, but design discription about PHWT just is acoording to standard and spc .
But we just find hardness control for sour services in the above document (girth weld and HAZ hardness is more than 250 HV10)
According to my experiences, girth weld and HAZ hardness of X60 mterial is lower than 250 HV10 without PWHT.(EVEN like this ,in other country iraq or iran ,we need apply PWHT for girth weld because feed design requirment)
So pls help us confirm whether girth weld and HAZ Apply PWHT or just control hardness,because it is the first bid in the saudi aramco.
thank you
CNPC daqing saudi
QAQC
From: materials-welding@
googlegroups.com [mailto:materials-welding@googlegroups.com ] On Behalf Of zhy370137@gmail.com
Sent: Wednesday, September 14, 2016 10:59 AM
To: Materials & Welding
Subject: [MW:25392] PWHT
Dear sir
good day
pls hlep us confirm whether we need apply PWHT for every girth weld according to your experience.
pipe ：API 5 L X60 HIC resistant pipe
welding method: CRC automatic
pipeline diameter and thickness:20inch 0.4inch(10MM)
Medium：sour condensate
pressure:960psi
pipeline distance：164km between two gas plant in saudi （safaniya plant to berris gas plant)
client：saudi aramco
CNPC daqing saudi
QAQC
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