Post Weld Heat Treatment 1

[fakhmed]

Dear All,

Can somebody help me to find any technical book or web site which gives the rules how can we determine if a PWHT is required for any carbon steel ?

Thank you

 

[weldtek]

The construction code will give requirements for PWHT.

 

[sk10009]

In case of piping, refer to the table of ASME CODE B31.3.
and in case of pressure vessure, refer to the UCS-56 of ASME CODE SEC.8

 

[fakhmed]

Thank you All,

I agree that some codes specifiy the requirement for PWHT, but some standards or codes do not specify clearly ex. AWS D1.1 or API 5L or AWWA C200...

I look for some thing to help the engineer to decide for PWHT when not clearly specified in the codes or standards.

Best Regards

 

[gtaw]

I use Annex I of AWS D1.1 Guideline for Alternate Methods for Determining Preheat, paragraph I6.

I like the method described in paragraph I6 because I can determine the chemistry of a sample taken from the material to be welded and determine the preheat requirements provided the carbon equivalency falls within the ranges listed. It also considers the level of hydrogen control and degree of restraint.

I do a lot of repairs on large presses and other equipment where the original drawings are "lost" or otherwise not available. Even when the drawings are available, the chemistry of the actual parts vary from what was specified. The preheat determined by Annex I is usually higher than some other methods, but more preheat is usually better than less preheat when working with heavy components made from carbon steel and low alloy high strength alloys, both hot rolled and cast.

I set up an Excel spread sheet that does most of the calculations once I plug in the chemistry.

I also used a book titled "Weldability of Steels" by R.D. Stout. My edition was copyrighted in 1987. You can probably find a copy at Amazon.

Post weld heat treatment is another story. Welding codes or references from ASM are helpful for determining stress relief, but there are other reasons for doing PWHT. The purpose of the PWHT must be determined before settling on a course of action.

Good luck - Al

 

[metengr]

I look for some thing to help the engineer to decide for PWHT when not clearly specified in the codes or standards.

I would recommend developing a spreadsheet and using ASME Boiler and Pressure Vessel Code (Section 1 and/or Section VIII) post weld heat requirements as a general guide. These PWHT requirements have been established based on many years of experience and research of materials fabrication.