Crack immediate welding 5

[MrPSK]

Dears,
I have a query,
Background:
During service 1" Line found leak, so we stopped the line and removed the spool to W/S to attend the repair.

Due to constraint we cannot fully cut and re-weld the joint, so planned to do weld on leaked section. During the welding it is noticed after done root, immediate weld crack was happening. Don't know why its happening (it happened 3 times). Need ur advice/suggestions to resolve this. Also needs to know why this happens?

Parent Metal : CS
Process : TIG
Filler Wire : ER70S-2

 

Lots of guesses ... one may even be correct!

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[TugboatEng]

Am I the only one that thinks this spool isn't carbon steel and the cracking is likely the result of incorrect filler material?

OP, you've contaminated the material with iron, it's possibly a copper nickel alloy. If you need to make this work, I suggest welding with nickel 99 to get it going.

 

You are not, Tugboat.
If I was shown the picture with no other information, I would not guess carbon steel.
Time to pull out the PMI gun.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[TugboatEng]

Or braze it. 56% silver will join most metals. This eliminates the need to know the specific alloy, especially now that this one has been contaminated.

 

Lot's of suggestions for off-road joining solutions.
WPSs are there for a reason.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[TugboatEng]

Oh I get it, but I doubt there is a WPS for mystery metal blended with ER70-S2. And that's even if the mystery metal is known. Short of replacement we are into Band-Aid territory now, which is my specialty.

 

We all know the best band-aid is duct tape. Just my 2 cents.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[r6155]

Welds and pipe apparently are with paint. This paint contaminate and can produce crack. May be.

Regards

 

[kingnero]

Duct tape, and apparently randomly adding preheat (as suggested above), which sounds like a contradictory advice given that the crack ticks off all major boxes of a hot crack.

 

Hmmm, are we closer to a root cause yet?

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[mfgenggear]

ya cut it all off and start over, weld whole new part, thoroughly clean and prep weld areas, and hire a welding engineer.
a proper clean, prep. preheat. gas mixtures, filler metal procedure

 

[MrPSK]

Dear Guys,
Thank you for your valuable feedback and suggestions. Finally it has been resolved by entirely cut and re-welded.
Reason:
It is evidenced that due to the Internal Corrosion there is significant Metal Loss (From the Fig, Weld Starting & Ending Point were with higher thickness but in the Middle area with lower thickness) due to this Solidification issue Crack formed.

 

"Not even a nuclear plant can be finished if you want to comply with all the rules"

Especially not a nuclear plant. I cam across a statistic showing the average cost of construction and refurbs was 220% of budget at the start of work.


"Everyone is entitled to their own opinions, but they are not entitled to their own facts."