## Finite Element Analysis to compute MAOP of corroded pipeline

## Finite Element Analysis to compute MAOP of corroded pipeline

(OP)

A pipeline has lost approx 50% of all thickness. Original wall thickness was 0.625-inch. Barlow's or B31G gives MAOP much lower than desired MAOP. [Desire MAOP 5,000 psi, computed MAOP based upon Barlow's 3200 psi].

Company hired a high flying engineering consulting company with top brain to show that the pipeline is still good for 5,000 psi based uon their Finite Element Analysis [FEA]. Is FEA acceptable for pipeline design, specially corroded ones?

Company hired a high flying engineering consulting company with top brain to show that the pipeline is still good for 5,000 psi based uon their Finite Element Analysis [FEA]. Is FEA acceptable for pipeline design, specially corroded ones?

## RE: Finite Element Analysis to compute MAOP of corroded pipeline

In some cases FEA may show that it is possible, but the Code will define the rules and it may not allow that analysis.

If the attack is non-uniform them the actual strength will be much lower than Barlow's would give you.

= = = = = = = = = = = = = = = = = = = =

P.E. Metallurgy, Plymouth Tube

## RE: Finite Element Analysis to compute MAOP of corroded pipeline

## RE: Finite Element Analysis to compute MAOP of corroded pipeline

## RE: Finite Element Analysis to compute MAOP of corroded pipeline

Barlow's or B31G???? Are you sure you are using B31G correctly then? What is the length of the corrosion?

## RE: Finite Element Analysis to compute MAOP of corroded pipeline

Code is Barlows: 30 cfr 250.1002

Corrosion is non-uniform

metengr: i will check with ASME FFS-1

brimmer: ABAQUS/Standard version 6.14.1

## RE: Finite Element Analysis to compute MAOP of corroded pipeline

You cannot directly apply Barlows to the corrosion, the models work differently (I'm not sure if this is what you are doing).

## RE: Finite Element Analysis to compute MAOP of corroded pipeline

I agree: API 579-1 / ASME FFS-1 Fitness-for-Service is good enough and B31G or B31GMod (RStreng 1) (both conservative), RStreng 2. DNV RPF101 (less conservative), etc ... are recognized as accepted methods for evaluating defects of corrosion (at this moment I do not remember those contemplated in api579-1 / ASME ffs-1).

The spreadsheet recommended by brimmer is a good tool.

## RE: Finite Element Analysis to compute MAOP of corroded pipeline

Finite Element Analysis of Burst Pressure for Pipelines With Long Corrosion Defects

Xian-Kui Zhu and Brian N. Leis

Paper No. PVP2012-78730, pp. 945-952; 8 pages

doi:10.1115/PVP2012-78730

From:

ASME 2012 Pressure Vessels and Piping Conference

Volume 6: Materials and Fabrication, Parts A and B

Toronto, Ontario, Canada, July 15–19, 2012

Conference Sponsors: Pressure Vessels and Piping Division

ISBN: 978-0-7918-5505-8

Copyright © 2012 by ASME

## RE: Finite Element Analysis to compute MAOP of corroded pipeline

If you assume and use FEA, you are wasting money and computing time, better put your computer to mine bitcoin.

If you measured it, the scenario is a little different, although I insist, the models are a good approximation more or less conservative, depending on the ability of the simulator to model the component with the defect, if you have good skill, you will be able to obtain slightly higher results than with the models.

It is not the paper recommended by brimmer, but it is also from the proceedings of a recognized congress.

http://www.gruppofrattura.it/ocs/index.php/ICF/icf...

## RE: Finite Element Analysis to compute MAOP of corroded pipeline

Also that was then, what is the thickness today or next week? That is pure conjecture. Once you get to depths and pits of 6+mm corrosion inhibitors become less effective and pits can deepen much more rapidly than before.

I agree with the others- there are many established and recognized means of analyzing pipelines with corrosion. FEA is only valid for the particular location you're looking at - to do FEA for an entire pipeline is ridiculous.

If it's only two or three locations, just add an external sleeve and forget about the analysis or cut it out and replace it. Sometimes it can take longer and cost more to analyse it to find you've got a problem than it does to simply fix the problem in the first place.

Lost metal won't come back....

Remember - More details = better answers

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