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Up Topic Welding Industry / General Welding Discussion / Welding ASTM A36 and Preheat
- - By mediadoll7 Date 09-15-2017 03:37
Hello. We are a steel structure fabricator and have a question regarding preheating.

We prepared a prequalified WPS and for the preheat we have included the below minimum preheat temperature according to table 3.3 (AWS D1.1-15).
Process: FCAW, 1/8~3/4 (32), 3/4~1-1/2 (50), 1-1/2~2-1/2 (150), Over 2-1/2 (225)

Now, our client has experienced cracking with another vendor and for prevention, they showed us Annex-H of the AWS D1.1-15.
They advised us to include the minimum preheat temperature for high restraint level in the WPS.

Using the hydrogen control method, the susceptibility index grouping was "C" and for 3/8–3/4 thickness, the minimum preheat temperature calculated as 65 degrees (the basis of the thickness was 0.47 inch (12mm).

Our question is does "high restraint level" (H6.2.5 Annex H) apply to ASTM A36 material due to the flexibility of the material because generally, due to the room temperature, we would like to proceed without an additional procedure for preheating. Therefore we would like to propose to our client that it would be satisfactory to classify only low restraint and medium restraint.

Thank you
Parent - By 803056 (*****) Date 09-15-2017 11:39
Annex H is a more conservative approach that takes the level of hydrogen control into consideration as well as the material thickness. However, it is one of the few welding standards that considers the degree of restraint. Thicker materials naturally offer more restraint that thinner materials. Patches, whether round or square, or rectangular are generally considered to be highly restrained. That being the case, Annex H is more conservative than most codes.

What are you assuming for hydrogen control based on welding process and electrode and exposure (SMAW) limits?

Up Topic Welding Industry / General Welding Discussion / Welding ASTM A36 and Preheat

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