Corrosion Coupons and Probes required ?

[nickypaliwal]

Our client has a non-corrosive fluid (NGL) pipeline. There is no chemical injection in the upstream of pipeline.

1) DO we still need corrosion probes/coupons on the pipeline when it goes underground and comes above ground ?

2) As I understand, coupons are generally used if there is any chemical injection in the stream ?

3) Also if the fluid is corrosive, no chemical injection, do we need corrosion coupons in that case ?

 

[brimmer]

well. that's totally up to you and your client!!! Are they required? No code will tell you so, have to use common sense here, if there is such a thing now a days. Perhaps they will monitor for corrosion in other ways, such as in-line inspection. Typically corrosion inhibition is not required on HVP lines, as the product is non-corrosive, and it is hard to distribute chemical because supposedly there is no free water; however depends on the source as I have seen some NGL lines with sever internal corrosion. Typically these lines have more strict BS&W monitors. Main thing is you monitor somehow if the product is corrosive, whether coupons or another method, but very rare to see coupons and chemical inhibition on NGL lines, check the cource of product to help determine if needed.

 

[SJones]

1) The question implies that there is a specified requirement to have such monitoring items installed. It is always a good idea to really challenge the need for them since minimising penetrations into a pipeline can only be a good thing from a risk point of view. Then see brimmer's discussion above.

2) Coupons can be used for a number of reasons. Take a look at NACE Publication 3T199.

3) See 2)

Steve Jones
Corrosion Management Consultant

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

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