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Nozzle crack
6

Nozzle crack

Nozzle crack

(OP)
Dear All,
Please find the attached snap, we found a crack circumferentially. The nozzle size is 6" and the material is SS.

The following plant is under construction and the vessel erected around 1yr back. There is an argument that because of pipe loads that are not supported yet, it created tension and lead to crack. Even I surprised that how a steel material started cracked like brittle for just for a few external loads. (This not the correct reason)

I clearly explained that any steel material that we design to be below the yield value. When the load beyond the ultimate limit it leads to fatigue and finally crack. This situation we can expect in operation if there is cyclic loading and the connected piping not supported properly. (which is an impossible situation).

Finally, I suspect that
- the material of the nozzle is not SS. (Maybe zinc coated?)
- (or) Because of corrosion
- (or) during welding, it created a weaker section and started crack initiation for the external loads.
- one more point that the vessel is A516bgr 70 and the nozzle is SS do you feel any possibility of this problem is due to dissimilar welding.

Experts kindly share your opinion and suggestions.

Thanks & Regards

RE: Nozzle crack

Any photo?

Regards

RE: Nozzle crack

(OP)
Dear All,
Please find the attached snap, we found a crack circumferentially. The nozzle size is 6" and the material is SS.

The following plant is under construction and the vessel erected around 1yr back. There is an argument that because of pipe loads that are not supported yet, it created tension and lead to crack. Even I surprised that how a steel material started cracked like brittle for just for a few external loads. (This not the correct reason)

I clearly explained that any steel material that we design to be below the yield value. When the load beyond the ultimate limit it leads to fatigue and finally crack. This situation we can expect in operation if there is cyclic loading and the connected piping not supported properly. (which is an impossible situation).

Finally, I suspect that
- the material of the nozzle is not SS. (Maybe zinc coated?)
- (or) Because of corrosion
- (or) during welding, it created a weaker section and started crack initiation for the external loads.
- one more point that the vessel is A516bgr 70 and the nozzle is SS do you feel any possibility of this problem is due to dissimilar welding.

Experts kindly share your opinion and suggestions.

Thanks & Regards

RE: Nozzle crack

Was the flange made in China ???

MJCronin
Sr. Process Engineer

RE: Nozzle crack

Something is off....flange is pitted and rusty, yet the weld looks like it was made yesterday.

RE: Nozzle crack

It's too far from the weld to have anything to do with welding or HAZ IMO.

This looks like a material defect to me assuming this flange has not been in operation.

Time to cut it off and send away to some forensic lab to determine material, material actual strength and hardness vs what the certificate says....

Whilst the corrosion isn't great for a SS flange it is not dreadful, but does call into question the preservation of the material assuming this is a saline atmosphere?

when you say SS what do you mean. There are many types of SS - is this duplex?
please be precise.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Nozzle crack

Agree with LittleInch ....

Send it off to the experts, pay their bills and get a report ...

Do you have a tracking system in place where similar flanges and forged products that are already installed, can be identified ? Could a similar cracked and defective component be installed in other systems ?

Does the flange have any identification at all ???

What country manufactured this flange ??

MJCronin
Sr. Process Engineer

RE: Nozzle crack

2
Failure analysis is not done by crowdsourcing -- send it to a reputable metallurgical lab for root cause failure analysis.

However, as alluded to by MJCronin, I have conducted multiple failure investigations of fittings where the name of the Far East country was essentially the root cause (ASME stamps notwithstanding).

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

RE: Nozzle crack

Contact the fabricator of the vessel before any action on the nozzle.
May be the nozzle was used as lifting lug.

Regards

RE: Nozzle crack

ironic_metallurgist is spot on. Couldn’t have said it better. Take his advice - it’s the best you’ll get

RE: Nozzle crack

You have to replace the flange anyway, so do as ironic metallurgist recommended.

RE: Nozzle crack

The fabricator is responsible for investigating and repairing the defect at no cost to the owner.

Regards

RE: Nozzle crack

If under warranty, the manufacturer is responsible for replacing the defective part and installing the replacement part at no cost to the owner but need not investigate the cause of failure in the defective material. If I were the owner, I would at least like to know if the part was the stainless steel forging specified, and if not, whether any similarly manufactured flanges have been installed.

The owner should never attempt to repair the defective part.

RE: Nozzle crack

You can use Positive Material Identification -PMI- instrument. Search in Google

Regards

RE: Nozzle crack

Have used PMI since 1970 thousands of times and the PMI unit in 1970 wasn't easily portable. If I were the owner, I would try cajoling the manufacturer to have a metallurgical analysis done on the part as per ironic metallurgist. I've had a number of occasions where one failure led to another and to quarantining numerous other flanges due to poor manufacturing issues.

RE: Nozzle crack

Remember, people the cost of replacement is not the only cost to account as you also have the cost of business interruption which will in all likelihood exceed the cost of replacement.

RE: Nozzle crack

4
PMI will not tell you carbon content and it certainly will not inform about metallurgical degradation that the nozzle may have suffered. Almost a complete waste of time (very but lucrative business for inspection companies who oversell PMI to the point of ridiculousness).

What you have is a weld neck flange (don't call it a nozzle) with a long circumferential crack in a location that is not readily explained by either stress or corrosion. Pay for the failure analysis ASAP and worry about who is responsible for the cost later. Lost production cost is orders of magnitude greater than one investigation.

Whatever you do, do not replace it with a spare that could have originated from the same lot of fittings, at least not until the FA is complete. Unless you are planning to run it on a temporary basis while you figure things out, but even that raises important safety questions.

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

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