DnV RP F103 vs. DnV RP B401: Coating Breakdown factor

Question

DnV RP F103 vs. DnV RP B401: Coating Breakdown factor

DudePipeliner (Mechanical)

(OP)

7 Jul 09 04:41

the coating breakdown coefficients (a and b) in DnV-RP-B401 where in order of 0.1 and 0.01.
these coefficient are remained unchanged in new revision of B401.
on the other hand, the DnV-RP-F103 proposes very different coefficients, which are in order of 0.001 and 0.0001; which leads to very light anodes.
What is the problem? It doesn't seem to be correct and I smell a rat in this approach???

SJones (Petroleum) · Answer 1 · 2009-07-07 20:15:52

There is no problem. Just look at the different scope of the two documents and the types of coatings they deal with. F103 is quoting specific breakdown factors for PIPELINE coatings whereas B401 is quoting breakdown factors for thin film organic coatings. Two different animals; two sets of breakdown factors.

Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04

DudePipeliner (Mechanical) · Answer 2 · 2009-07-07 22:02:03

Yes Steve, I know about the scopes and you are right. however, I mean the difference between previous B401 (1993) which was also applicable for pipelines and the new F103 (2003).
does the large difference between breakdown factors is related to improvements in Coating quality?
I found a document from Norway Oil Authority mentioned that this is the result of higher quality coatings, but the F103 just refers to F106 & F102 for coating spec.
What I am exactly worry about is to use F103 in my project, while the coating will not be as advanced as supposed to be.
In the other word, how could I add some conservatism in to my design? (there are some options in F103 for that, which one is reasonable?)

Pipeliner Dude
Offshore Pipeline Engineer

SJones (Petroleum) · Answer 3 · 2009-07-08 01:46:05

DNV have developed the coating and CP specifications in parallel. In quoting the breakdown factors in F103 they have accounted for long term experience with pipeline coatings on the basis that the quality of coating and the application will meet, or exceed, the minimum requirements of F106 and F102. If you are concerned that the pipe coating will not achieve either F106 quality or a comparable level of quality using another standard, then you have little option but to revert back to the default values for an 'ordinary marine coating'.

Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04

DudePipeliner (Mechanical) · Answer 4 · 2009-07-08 01:58:41

Thanks Steve,
It seems that's the best option.

Pipeliner Dude
Offshore Pipeline Engineer

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DnV RP F103 vs. DnV RP B401: Coating Breakdown factor