Preheat of base metals in ASME?
Preheat of base metals in ASME?
(OP)
According to AWS D1.1 5.6 one of the paragraphs states "This preheat and all subsequent minimum interpass temperatures shall be maintained during the welding operation for a distance at least equal to the thickness of the thickest welded part( but not less than 3" in all directions from the point of welding".
Where can I find this in ASME?
Where can I find this in ASME?





RE: Preheat of base metals in ASME?
jt
RE: Preheat of base metals in ASME?
RE: Preheat of base metals in ASME?
I'm trying to find it in writing so I can show it to our welders how large of an area is necessary to preheat.
DVWE I'll look into the appendix R.
Thanks
RE: Preheat of base metals in ASME?
RE: Preheat of base metals in ASME?
It is governed by the applicable fabrication code you are working to, not to ASME IX.
For example ASME B31.3 Clause 330.1.4 Preheat Zone states "The preheat zone shall extend at least 25 mm (1 in) beyond each edge of the weld."
What code are you working to ?
What is minimum preheat temperature of WPS ?
What is average ambient temperature in your area ?
What materials are you welding ?
A bit more info and we may be able to assist further,
Regards,
Kiwi
RE: Preheat of base metals in ASME?
Kiwi I'm welding P6 CA6NM with GTAW and preheat of 200 degrees.
Ambient temp is 70 degrees.
I'm not sure what fabrication code I'm working to. Where do I find - ASME B31.3 Clause 330.1.4 Preheat Zone states "The preheat zone shall extend at least 25 mm (1 in) beyond each edge of the weld."
RE: Preheat of base metals in ASME?
If you are unsure about what Code or Standard you are working to I would use AWS preheat requirements as you stated above. Otherwise, you can cherry pick preheat recommendations from numerous sources.
If you have a copy, in ASME B31.3.
RE: Preheat of base metals in ASME?
I don't know where the 3" rule originated, but I have seen it specified many times and in many documents. Greater extent of preheat also helps mitigate distortion. ASME only gives 'recommended' preheat values in non-mandatory appendices, but it would be prudent to treat them as 'mandatory' minimums. Any lawyer certainly would ...
RE: Preheat of base metals in ASME?
RE: Preheat of base metals in ASME?
This welding was done on a diffusor for a pump and the welder preheated the whole part. It was a minor weld repair, only needed localized preheat. Because the whole part was preheated, warpage occurred. So I'm trying to explain to the welders that in some cases it is not necessary to preheat the whole part. But I'm trying to gather written proof from ASME.
Thanks for all the help everyone!
RE: Preheat of base metals in ASME?
RE: Preheat of base metals in ASME?
No way. I would bet what little savings I have it was the weld repair itself that caused the warpage.
RE: Preheat of base metals in ASME?
All the ASME codes list both required and/or recommended minimum preheat temperatures dependent on the material.
For example,in B31.3 P numbers 1,3,6,7,8,9 have recommended minimum preheat and P numbers 4,5,10 & 11 have required minimum preheat.
For CA6NM (P 6)the following requirements / recommendations are listed for minimum preheat.
ASME B31.3
300 degrees F / 149 degrees C - Recommended.
Minimum of 1" from weld edge - Required.
ASME B31.1
400 degrees F / 200 C - Required
Minimum of 3" or 1.5 times base metal thickness (whichever is greater) - Required
ASME VIII Div 1
400 degrees F / 204 degrees C - Recommended
Hope that helps regards,
Kiwi
RE: Preheat of base metals in ASME?
I am fully aware of ASME Boiler & Pressure Vessel and Piping Codes' preheat requirements/recommendations. They do not address how to preheat a casting to affect a repair that will not cause distortion. Left unsupervised without proper direction, I have seen welders over heat, under heat, and otherwise misuse torch preheating, especially when using oxy-fuel gas cutting torches as rosebuds, or when applying rosebud heating and leaving it on, directed in one location on the part while taking a break.
Also Code requirements may be inadequate. I once recommended to a major vessel manufacturer to increase its preheat temperature on some 4" wall Manganese-Molybdenum vessels. They did not heed my recommendation initially, claiming all they had to do was follow Code. They had to repair two full circumferential seams in the 10 ft diameter vessel shell after both fully cracked during a weekend shutdown; they preheated as I recommended thereafter - curiously, no more cracking.
RE: Preheat of base metals in ASME?
Sincere apologies for misinterpreting your post.
Any thoughts on the OPs preheat of 200 degrees which is 100 - 200 degrees below ASME requirements / recommendations ?
Regards,
Kiwi
RE: Preheat of base metals in ASME?
RE: Preheat of base metals in ASME?
If proper preheat requirements do not exist in the WPS, put them in. I recommend uniform heating of the casting - put it in an old, household electric oven for an hour or so.
RE: Preheat of base metals in ASME?