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Up Topic Welding Industry / Metallurgy / Stainless Cracking?
- - By 2006strat (***) Date 04-03-2017 16:55
I welded two 10" sch 10 stub ends on yesterday where a new valve will be going.  The prep was die checked, my bead was die checked, then this morning, they die checked the cap.  4" from one of the welds going around the pipe was a large crack.  On the opposite side, where weld #2 is, cracks were found about 1/2" from the weld running away from the weld with the pipe.  Nothing was put on the welds to cool, they were left to cool on there own.  No heat was added today prior die check.  It's 316 to 316.  I am using 316 3/32 wire.  My machine is set lower then normal and I kept the heat the same bead and cap.  MY QUESTION:  what would cause this pipe to crack?  Engineers are leading to just cutting back 10' and doing it again.  I don't want my name on it if in the future it happens again.  The 10" line is coming off a reactor.  Only thing I can come up with is Stress corrosion cracking.  They have the whole line U bolted to the structure with no room to breath.  If you look inside, the previous welds are ugly, ugly, I know somebody wouldn't weld like that.  I am just trying to figure out if I didn't something wrong.  My root passes were blue, red and I did purge with plenty argon.
Parent - - By 522029 (***) Date 04-04-2017 13:22 Edited 04-04-2017 13:40
316,            use 309S 309 309CB, 310
310,            uses  310S, 314 310 310CB, 310MO
316, 316L    uses 316, 316L 309MO, 317
316H           uses316H 309MO, 317

What was the carbon designation (L) or (H) on your material?


The chart didn't copy correctly.  Here is the link:
Parent - - By 2006strat (***) Date 04-05-2017 10:39
Inspectors and engineers couldn't pin point the root cause of cracks.  1.) could be the place of heat effective zone is where the new cut was made on the old material.  2.) Stress Corosion Crack-from the base old material being to contaminated with Vinyl Chloride.  3.)  the material pipe structure already was cracked under stress and the heat just expanded it.    Thank you for the reply.  I have that page saved now.
Parent - By 522029 (***) Date 04-05-2017 12:58
You are welcome.

Up Topic Welding Industry / Metallurgy / Stainless Cracking?

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