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Crack immediate welding
5

Crack immediate welding

Crack immediate welding

(OP)
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

RE: Crack immediate welding

What's inside the pipe.

RE: Crack immediate welding

There is more weld than pipe in that spool....

RE: Crack immediate welding

MintJulep's question will probably lead you straight to the answer. Also, I think I see porosity in the end crater. As there are no visible pores throughout the weld, I think that's due to welder error.

The history of this section will probably also contribute to the answer. Why all the previous repairs?

Due to constraint we cannot fully cut and re-weld the joint, so planned to do weld on leaked section.
I don't udnerstand, did you weld this on a welding table, so not constrained (part can shrink freely), or while still installed in the process piping?

RE: Crack immediate welding

With all the previous repais, it would appear that you have the wrong material selection for the service. Welding over a crack is difficult enough but welding over a contaminated crack is almost an assured failure.

RE: Crack immediate welding

(OP)
Dear kingnero,
Actually this is app 250mm length spool and the constraint was its Orifice type spool, so this the reason u can see more welds in that pipe spool. Weld was on welding table only. Also another constraint was due the Name plate (u can see in the pic) was in the other side of weld. so that we cannot able to cut the weld joint fully to make new weld.

RE: Crack immediate welding

(OP)
Dear MintJulep
Inside of the Pipe is Orifice type set up.

RE: Crack immediate welding

Excellent link... thanks

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

RE: Crack immediate welding

2
What line? What leak?

Here we go with another crowdsourcing failure investigation based on one picture...just remember, you get what you pay for.

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

RE: Crack immediate welding

I find these wierd threads great... they are what makes Eng-Tips what it is. Some of the links posted are really interesting, as the one above. I don't think of it as crowdsourcing... it's informative and educational.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

RE: Crack immediate welding

(OP)
Dear MintJulep
Service that the pipe carries is Aquifer Water.
I agree with you, i also thought of Solidification crack due to its centreline and its appearance.

RE: Crack immediate welding

It appears that there are 2 welds immediately adjacent on either side of the cracked weld repair. This indicates very high residual stress in tension acting on the weld being repaired. This may be the worst design from a welding standpont that I have seen. There are ways to make the welds involved but your way has proven an unmitigated failure.

RE: Crack immediate welding

It might be time to replace a part of the pipe...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

RE: Crack immediate welding

Ambient temperature?
Preheat temperature?, secuence before and after welding?, extension length of preheat at each side of weld?
Welder is qualified?.

Regards

RE: Crack immediate welding

The name plate should not be a constraint, you take it off if needed and attach back on after completing the weld.

Try preheating if you didn't and make sure its the correct filler material.

I have a hard time believing any code would allow you to lay a weld against joint welds like that.

Edit: kingnero is correct, preheat is not the answer for what appears to be hot cracking.

RE: Crack immediate welding

"Not even a nuclear plant can be finished if you want to comply with all the rules" For that the non-conformity report was invented.

Regards

RE: Crack immediate welding

Hehehehehe..

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

RE: Crack immediate welding

(OP)
Thank You for all for your valuable suggestions and feedback.

RE: Crack immediate welding

Welded area colour tells you the story, I guess. You probably used high current, and burned the area. I agree with other comments which might be other causes for this kind of failure.
It seems that the crack comes from fast solidification. Same think can happen high carbon steel welding, the cracks may even happen during the welding. You really need to know what the base material is.

There is gold colour accumulation of material in line with the weld crack. Can you tell us what it is? There might be material contamination in the area as well.

RE: Crack immediate welding

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

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

RE: Crack immediate welding

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.

RE: Crack immediate welding

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."

RE: Crack immediate welding

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.

RE: Crack immediate welding

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."

RE: Crack immediate welding

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.

RE: Crack immediate welding

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."

RE: Crack immediate welding

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

Regards

RE: Crack immediate welding

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.

RE: Crack immediate welding

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."

RE: Crack immediate welding

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

RE: Crack immediate welding

(OP)
Dear Guys2thumbsup,
Thank you for your valuable feedback and suggestions. Finally it has been resolved by entirely cut and re-welded.medal
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.

RE: Crack immediate welding

Quote (r6155)

"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."

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