SS welding - Pickling & Passivation

[Joss10]

During a weld failure analysis (SS 304 FCAW G) we concluded that the problem would have been due to the lack of acid cleaning (Pickling & passivation) of the weld.
Final acid cleaning is not shown as variable of any kind for that welding process, being that in SS welds that final cleaning is important.
Any opinion on this will be appreciated.

 

[SJones]

What was the failure mechanism?

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[weldstan]

And what were the fluid/service conditions?

 

[meltedEng]

Codes which list "variables" are generally describing the minimum requirement.

ASME has a clause which says, and I'm paraphrasing "if it caused a failure in your PQR or known to affect fusion, it is now an essential variable".

 

[Joss10]

Sorry for this late reply.
Corrosion mechanism is not well defined yet but its effect is "pitting".
About the fluid: it is a tank that after its final hydraulic test would not have been dried and was abandoned for almost a year.

 

[IFRs]

Was this a SS nozzle welded to a CS shell? If so, what cleaning / passivating was specified?

 

[weldstan]

Is pitting only in the deposited weld metal and HAZ and/or heat tinted area? Was tank left open to the atmosphere during storage/abandonment? What were the storage conditions; for example marine or heavy industrial environment?

 

[gtaw]

We had a discussion about a similar situation a couple of weeks ago. You can probably still find here if you nose around. You may be looking at MIC. It can usually be found in the HAZ adjacent to the weld. If, on the dry side you find drips and iridescent deposits, it is a good chance you have a case of MIC.
Standing, stagnant water and austenitic stainless steel do not play nice with each other.


Best regards - Al

 

[SJones]

Try this

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.