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intelligent pig -Preferential Weld Root Corrosion

intelligent pig -Preferential Weld Root Corrosion

intelligent pig -Preferential Weld Root Corrosion

(OP)
Hi Guys,
The management raised concerns that the nickel content of welding consumables used in the construction of one of our gas Production Pipeline (1.5% Ni) may give rise to unacceptably high corrosion risks by promoting Preferential Weld Root Corrosion (PWC).

My question is : what will be the engineering justification to run the  intelligent pig and is pigging the only solution?

I would rally appreciated your feedbacks!

Thank you
 

RE: intelligent pig -Preferential Weld Root Corrosion

Consult the Energy Institute Guidelines For Corrosion Management, Annex B6.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04
 

RE: intelligent pig -Preferential Weld Root Corrosion

Have you Identified the specific corrosion mechanisms, are you using corrosion inhibitors?

A profile / feeler pig may be more economical and provide better results.

RE: intelligent pig -Preferential Weld Root Corrosion

(OP)
rustbuster; thanks for replying back,the corrsion mechanism is  Preferential Weld Root Corrosion and yes we do use a corrsion inhibitor. however there are no historical date with regards to the corrosion inhibitor performance over the root of pipeline welds!

SJones: thanks  

RE: intelligent pig -Preferential Weld Root Corrosion

Apparantly you are looking at galvanic corrosion effects rather than wet H2S service where SCC would be more pervasive, according to NACE, in the 1.5% Ni deposited filler. The root pass (corrosion barrier) will be diluted to approximatel 1% Ni and it is highly doubtful that appreciable galvanic effects would occur to cause preferential corrosion in the root greater than would normally occur with closer matching carbon steel filler metal.  

RE: intelligent pig -Preferential Weld Root Corrosion

While PWC occurrs, it is unpredictable.  So should pig because you have a pipeline, and PWC is one of the issues to look for.

RE: intelligent pig -Preferential Weld Root Corrosion

(OP)
enmax, Thank  you and all the best of 2011  

RE: intelligent pig -Preferential Weld Root Corrosion

Sorry to come so late to topic.

If the line is not buried, then the best inspection would be TOFD of the root region. It will show very clearly with an accurate maximum height measurement. But their must be good access to bare metal (or thinly coated) pipe surfaces adjacent to the weld.

Quick, reliable and effective.

RE: intelligent pig -Preferential Weld Root Corrosion

(OP)
ndeguy; Thank you!

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