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Anonymous Poster #1

Post Welding Heat Treatment

01/09/2015 2:11 AM

in which circumstances PWHT can be avoided at all sort of services like gas (sweat/sour), oil, water, & etc, plz do mention standards
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MACA
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#1

Re: post welding heat treatment

01/09/2015 3:09 AM

Welding is a complex subject. I'd say speak to a welding engineer but I believe if you need to 'avoid' post weld heat treatment you can do buttering with another metal. We do it when we are not allowed to PWHT certain materials but it is such a vast subject I don't think anyone can give you an answer here.
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IdeaSmith
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#2

Re: post welding heat treatment

01/09/2015 3:18 AM

You will not be able to avoid it if it is necessary! Avoiding it is at the peril of the quality of the weld.

Above is true for any standard!

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Whitephone
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#3

Re: Post Welding Heat Treatment

01/09/2015 7:21 AM

Three reasons to apply PWHT are: 1.- Material, 2.- Thickness, 3.- Service.
the three are clearly defined in ASME B.31.3
WP
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Anonymous Poster #1
#4
In reply to #3

Re: Post Welding Heat Treatment

01/09/2015 7:39 AM

can I've copy of ASME B31.3
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MACA
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#5
In reply to #4

Re: Post Welding Heat Treatment

01/09/2015 8:42 AM

To answer your last question the answer is yes. However, I think the question you are actually asking is 'can you give me a free copy of the standard' to which the answer is (from me anyway) no.
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Original_Macgyver
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#6

Re: Post Welding Heat Treatment

01/09/2015 9:43 AM

The only way to avoid it is to follow a specification that says "NO PWHT NEEDED". The only way for us to give you a correct "answer", we need a correct "question".

  1. What is the material?
  2. What is the welding process?
  3. Filler material?
  4. Blueprint weld specification?

Good luck?

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Kulas
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#7

Re: Post Welding Heat Treatment

01/09/2015 11:41 AM

In which circumstances a PWHT can be avoided? --If others are doing it before you.

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bigg
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#8

Re: Post Welding Heat Treatment

01/09/2015 12:05 PM

You kind of asked the question backwards - it should be 'in which circumstances is PWHT required?' So the answer is, 'it can be avoided except where it is required'. Whitehouse in post #3 answered in general terms of where it is required.
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Whitephone
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#9
In reply to #8

Re: Post Welding Heat Treatment

01/09/2015 12:23 PM

EEHHH, Whitephone, se il vous plaît. Je,Je
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bigg
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#11
In reply to #9

Re: Post Welding Heat Treatment

01/09/2015 1:46 PM

Oops, sorry for the demotion .
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Crabtree
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#10

Re: Post Welding Heat Treatment

01/09/2015 12:28 PM

Well, I wouldn't PWHT plastic pipe, Mildred.

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srijitpv
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#12

Re: Post Welding Heat Treatment

01/12/2015 2:56 PM

Take it other way, where ever there is a risk of environmentally-assisted cracking, PWHT cannot be avoided.

As per ASME code, for pressure vessels and piping, if the thickness of the parts being welded exceeds a specified value, PWHT cannot be avoided. Charpy test properties of the material and the minimum service temperature required should determine this. In general, US & UK codes limit the thickness of C / C-Mn Steels to 32 mm, beyond which PWHT cannot be avoided whether it be pressure vessel, piping or storage tank.

When comes to the low alloy steels, ASME B31.3 has set a limit thickeness of 19 mm, above which PWHT cannot be avoided, I assume...

Please refer ASME Section VIII - Div. 1, UCS-56 for Post Weld Heat Treatment requirements detailed.

Also refer UCS-68 where it is mentioned that PWHT cannot be avoided when minimum design metal temperature is colder than -55 deg. F...

If you are not seroius to know the fact, but wants to avoid PWHT in a particular case, do take the help of an Authorised Inspector (Certified) under his supervison, and in this circumstance, you may be able to avoid so called PWHT, but surely just NOT based on service medium like gas, oil, water, etc.
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Mahmoud El sayed
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Engineering Fields - Mechanical Engineering - Static equipment Mechnical engineer Engineering Fields - Piping Design Engineering - Static equpment mechanical engineer Engineering Fields - Petroleum Engineering - Static equipment Mechnical engineer

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#13
In reply to #12

Re: Post Welding Heat Treatment

01/22/2015 6:28 AM

great answer, i would like to add last point to the PWHT requirements regarding the pressure vessels as per ASME code VIII Div.1 UCS-79 as it stated that the required material will need heat treatment when the resulting fiber elongation is more than 5% from the as rolled condition.

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srijitpv
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#14
In reply to #13

Re: Post Welding Heat Treatment

01/23/2015 1:38 PM

You have an Eagles eye...Meanwhile thanks for the appreciation...
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KGM
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#15
In reply to #14

Re: Post Welding Heat Treatment

01/24/2015 1:59 AM

Thanks Sir, can I've your email.

Regard,

Mujtaba
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Users who posted comments:

Anonymous Poster (1); bigg (2); Crabtree (1); IdeaSmith (1); KGM (1); Kulas (1); MACA (2); Mahmoud El sayed (1); Original_Macgyver (1); srijitpv (2); Whitephone (2)

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