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stainless steel 304 welded with alloy steel if possible or not

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Apr 6, 2020
6
good afternoon

a stainless steel a 312 type 304 earth lug plate fillet weld with alloy steel a 335 grade p11 .my query is which filler wire is used to weld a joint. stainless steel line can not possible to preheat and post weld heat treatment .why because its low thermal conductivity and high thermal expansion . but alloy p11 needed a preheat and post weld heat treatment to prevent the oxidation problem .. so for this case what can we do to solve this problem sir.[preheat and pwht needed or not]

thanking you
 
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A nickel base alloy filler metal should be used if PWHT is required.
 
If this is a grounding lug to provide a path for stry currents, lighting, etc., why not make the lug from the same stainless alloy as the pipe? Just asking the question.

Best regards - Al
 
yes sir your question is correct we can use stainless alloy but my site earthing is open space so more possibility to corrosion . so stainless steel is more resistant to corrosion than stainless alloy steel so we are using stainless steel .

hello sir mr weldstan

can you please explain breefly about previous questions .. how to you choose the ERNiCr-3 and ENiCrFe-3 .then preheat and post weld heat treatment chart is not mentioned the temperature of stainless steel .so which temperature chart to we consider to conduct a pwht .and then stainless steel 550 to 700 degree cromium oxide layer breaking and so possiblity of sensidation to make corrosion . this all content for my point of view . if its wrong please you explain correct answer sir .

thank for your replay sir i hope to waiting for your answer

 
I am not clear what you are doing. Is the 304 lug welded to a stainless steel pipe? If so, why is P11 even mentioned? P11 is not stainless alloy steel as you seem to indicate. When welding P11 to type 304 stainless steel and PWHT is required by the Code of construction, a filler metal like those recommended is used because it has a coefficient of expansion intermediant between the low alloy steel and the austenitic stainless steel being welded to each other. This reeduces residual welding stress incurred during cooling from the PWHT temperature. And PWHT is not always required when this dissimilar weld is made.
 
Finally why do you think P11 requires PWHT "to prevent oxidation problem"? It is not!
 
Another classic case where the OP loses interest, goes incognito.
This is becoming a regular feature of this forum.
Either the experts are managing the show very well or the industry is running without them!

DHURJATI SEN
Kolkata, India

 
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