RE: PWHT REQUIREMENT

From: <Al>
Date: Mon Mar 15 2004 - 22:15:00 EST

Not sure of the question since it covers two areas. NACE MRP0175 requires PWHT for all materials when the it is determined the service is SOUR. The Chemical (mole) basis for making this determination has to be undertaken by the owner (only they know the content of their product).
All this is spelt out in the 2nd para of the first page of NACE. It is basedon the partial pressure of H2S. (the sulphide concentration that would give rise to SCC).

But, There are many reasons for applying PWHT..too many to go into here.NACE is only one of many hundreds of reasons. One of them (MEA/DEA) was discussed here about a week ago.

Re TAble 331.1.1 (B31.3)
The code , including PWHT requirements as outlined in Table 331.1.1 only advises what the requirements are when (once) you have determined it is necessary. it does not make the necessity determination for you. bear in mind the ASMA codes are only minimum requirements. They also do not cover the decisions required to be made about application of the requirements or when the minimum is sufficient.

hope this helps understand or make the decisions you need. Your office in Calgary
can help with those determinations.

-----Original Message-----
From: Narendra Roy [mailto:narendra_roy@yahoo.com] Sent: Monday, March 15, 2004 7:54 PM
To: <a href="/group/PipingDesign/post?postID=fkCkqj5V1O6KZRNviIPKAlN4c174ZcUlR2dG52FMzzozVL8EaoFsrrbZuIoc8csdClTqBKNWZNyhQ-j-SbkpeTEif8EabeE">PipingDesign@yahoogroups.com</a> Subject: Re: [PipingDesign] PWHT REQUIREMENT

Dear Pravin
NACE HIC Resistant Qualified materials do require PWHT even if they are exempted by the ASME Heat Treatment table. This is a good engineering practice considering the long safe life of the piping components. The failure expected in such environment is due to stress corrosion cracking and this damage can be reduced by keeping the stresses to the minimum level possible, and stress relieving of ineternal stresses is by PWHT. Overdesign such piping components for prolonged safe life, this is the additional tips.
NK Roy

• "Patil, Pravin" <Pravin.Patil@veco.com> wrote:
  > Dear Friends,
  >
  > Does NACE material requires PWHT irrespective of the
  > thickness of the pipes
  > or table 331.1.1 (requirements of heat treatment) is
  > the only criteria to
  > specify heat treatment ?
  >
  > Best regards
  >
  > Pravin V. Patil
  > Piping Engineer
  > VECO Engineering
  > Suite 902, Al otaiba Building,
  > Electra Street, Abudhabi
  > UAE
  > Ph. 00971 02 6346640 Ext. 241
  > Mobile No. 00971 50 3577457
  > EMail: <a href="/group/PipingDesign/post?postID=OEVin7rnOd34h_Y50GjF1l2VUkP6bxgjW0rlHxlvKlrv1TemDw6XKaSDvcy2WwvSCb7p_rz2heO5BzGn4zYH">pravin.patil@veco.com</a>
  >
  >
  >
  

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Yahoo! Groups Links Received on Mon Mar 15 22:15:00 2004