Pipeline life expectancy 1

[SmoothGear]

Hi everyone.

I'm completely new to pipeline engineering and need to know how to determine the remaining life of a network's section. Here are some details:

-It's an oil pipeline network
-It's a 90º bent section
-The damage that has been reported is dents and wall thinning.

So right now I've been checking some books and also ASME codes, but still I'm wondering how many factors have to be taken into the equation, I believe erosion, corrosion, thermal loadings and local stress concentration are all of them.

I read about some damage assesment graphics that relate defect length to defect depth to determine if the piping needs to be repaired, changed or not. Where can I find this? (This is good alternative to what I'm looking for).

I would appreciate if you gave some insight in this matters and how to obtain all the pertaining parameters.

Also, I'm not sure if all of this has to be done in some numerical simulation software or if there is an easier way to do it by graphs, tables, codes or else.

I know this is a whole lot of information, hope someone can help me out.

Thank you so much!

 

[SJones]

The title and the text are mixing two different concepts: fitness for service and remnant life. For the former, one of the best documents is the Pipeline Defect Assessment Manual

http://www.penspenintegrity.com/services/pdam/

http://www.penspenintegrity.com/downloads/pdam/pdam-dents.pdf

The latter is based upon a prediction of when pipeline anomalies will achieve the dimensions corresponding to a limit state such as fracture or plastic collapse.

Overall, these are both complex subjects, and may be under regulatory implications. It is recommended that expert support is engaged rather than seeking solutions on an internet forum.

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.

 

[BigInch]

You might look at B31.8S and B31G as well as this PHMSA guide presentation

http://primis.phmsa.dot.gov/rd/mtgs/062409/MikeRosenfeld.pdf

I hate Windowz 8!!!!

 

[SmoothGear]

Thanks for your help, I'll see to it that we get support on the subject.

 

[kacarrol]

I thought API had some standards on this stuff too? Maybe API 579?

Many moons ago I remember doing some calculations on piping with thinned walls to determine whether it could keep operating and if it could keep going how long it could keep going for with the historical rate of corrosion. I'm pretty sure it was an API standard we used.

Regards,
K

 

[SmoothGear]

Thanks for your help, I'll check that too

 

[TGS4]

My recommendation for you is to start with an approach that examines the various potential failure modes: plastic collapse, buckling, fatigue, etc. Then, use your original Codes of construction to determine appropriate design margins against the various failure modes. Then, examine the various defects and figure out how they interact and can "cause" failure for the various failure modes. If some of the degradation mechanisms are continuous (think annual general corrosion rate), then determine the limit state for the various failure modes. Then compare the limit state to the current condition. Then use your degradation rate to determine the remaining life.

 

[SJones]

API 579-1/ASME FFS-1 could be used to assess the anomalies, but it is not a very pipeline orientated document and the results could be over conservative in a pipeline context. Not necessarily a bad thing - until it suggests retire and replace immediately. The exact assessment methodology should really be defined in the pipeline owner's integrity management system.

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.

 

[LittleInch]

The thing that concerns me about this question is that someone who is "completely new to pipeline engineering" is apparently being asked to determine remaining life and how to "determine the remaining life of a network's section".

I can't imagine any responsible owner / operator doing this as the consequences are too bad to contemplate.

Dents are often caused by excavator buckets and end up with not only a dent, but a gouge within the dent. These are highly prone to sudden failure caused by stress concentration at the bottom of the groove and work hardening of the material leading to failure by fatigue cracking.

I'm glad you will get some proper support on the subject.

You actually have some good material linked here, but please use this as background info for use during conversations with people that know what they are doing and not try to do it yourself.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[weldstan]

Location of mechanical damage is also important; e.g., extrados, intrados or neutral axis and relatiion to areas of wall thinning due to corrosion.

 

[SmoothGear]

Thanks again for all your help, it's really been of help. With all the material everyone's been so kind to give me I've exposed the real situation to my superiors and everything worked out well. Right now we're assesing the situation and looking for a specialist.

LittleInch:

Hahaha, same thought here. Truth is that when I was entrusted with this task those where my exact words, my knowledge could only take me so far as to plastic collapse analysis, and believe me, I know that would have gone wrong in terms of safety.


Thanks everyone.

 

[BigInch]

Good job for someone inexperienced in this line.

​

At least he's not going to screw up anything that's not already screwed up.

I hate Windowz 8!!!!

 

[BigInch]

SmoothGear,
Ran into this PHMSA presentation.
Encapsulates the main ideas.

I hate Windowz 8!!!!

 

[jaxon123]

You may try using ASME B31G "Manual for Determining the Remaining Strength of Corroded Pipelines a Supplement to ASME B31 Code for Pressure Piping"

 

[kacarrol]

Just a slightly related point of interest. I received the ASME PVP Conference email today (for the July 20-24 conference) and one of the technical tutorials being offered is:

Application of API 579-1/ASME FFS-1 and BS-7910 Fitness-for-Service Procedures
Presented by: Bostjan Bezensek, Shell UK, Ltd.; Isabel Hadley, TWI Ltd.; David Osage and Robert Brown, The Equity Engineering Group, Inc.

Just thought I'd throw that out there as an FYI.

Cheers,
K

 

[SmoothGear]

Thanks for your trouble!