Pipe Material 5

[LeitoGM]

Happy Monday All,

I need to asses the integrity of a 10 meter long 10 inch pipe (since it is a dead leg). However, after months of research, we have been unable to determine its origin (MATL).

As a result, What would be the best method to determine the pipe's material and WT? are the any non-destructive methods? UT scans might be useless since there might be corrosion in the line already.

I look forward to your replies.

Thank you,

LeitoGM

 

[MikeHalloran]

It's probably cheaper to just buy a new pipe.
... and keep track of the certs this time.



Mike Halloran
Pembroke Pines, FL, USA

 

[LeitoGM]

very good point, but what kind of testings can be carried out in order to determine the Matl?

I know there's the sample one, where you grab a cube and send it to the lab, but what other methods are out there?

Thank you

 

[racookpe1978]

Dead end line? What fluid, pressure, temperature, cyclic or steady pressure & service? What length of service so far? What length of service is desired?
What are it's fittings and what material are the fitting?

 

[XL83NL]

@ racookpe; As the OP mentioned in his first, the material is unknown

 

[SJones]

API Publication 578

Why might UT scans be useless? If you are assessing the integrity of the pipe, aren't you interested in ascertaining remaining wall thickness, assuming that the finally identified material is subject to metal loss in the environment, which can be evaluated with an appropriate UT procedure? If you have the nominal pipe dimensions, tangential radiography may also be of use

http://www-pub.iaea.org/MTCD/publications/PDF/te_1445_web.pdf‎

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]

LeitoGM

As far as I know there are no NDT methods of determining either composition or more importantly physical properties (SMYS etc). In these circumstances, you need to assume the worst and take the lowest possible SMYS of a pipe either in the plant where you are or what was available at the time. Grade B is probably a reasonably safe bet, but think about what you would say if questioned in court about why you assumed any higher value after the pipe failed and injured someone or something....

As for wt, why is UT "useless". As S Jones says, what you need to "assess the integrity" is what metal you have left today, not what you started with. However if you take enough readings (30+) you will find un corroded areas which should allow you to estimate the original wall thickness.

My motto: Learn something new every day

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

 

[BigInch]

Check your design code. If it permits pipe of unknown yield strength, it may be limited to using nothing more than a 20,000 psi yield strength.

I hate Windowz 8!!!!

 

[jbeckhou]

I would suggest PMI (positive material identification), UT and Hardness testing.

Petrotrim Services, LLC

http://www.petrotrim.com

 

[racookpe1978]

True. The "pipe" material is unknown. But the fittings ARE stamped on the sides of the fittings (tee, cap, etc) and so provide more information.


Regardless of pipe material, fitting strength and corrosion resistance is as important/more important than pipe wall material in retaining the fluid over time.

 

[Duwe6]

For you to certify this piece of pipe as to it meeting a Spec & Grade, you have to perform all the tests per that Spec. Typically, tensile testing and some kind of bend or flattening test, in addition to the chemistry. Being destructive tests, they are kind of impractical for your problem. If it were mine, I'd go with what LittleInch suggested.

NOTE: for carbon steel, meaningful PMI will require carbon content in addition to the usual alloying element percentages. And you cannot determine carbon content with an x-ray fluorescence PMI 'gun'.

 

[rconner]

While I'm not sure exactly what you have been asked to do, I think you have gotten some very good suggestions. If e.g. a "PMI" or other examination reveals basically some flavor of plain, unalloyed carbon steel, I guess portable hardness readings test might give at least a hint as to strength level, carbon content etc.
I gather by "MATL" you are probably talking about what kind of material the pipe is made out of, and by "UT" you are probably talking about ultrasonic testing (or ultrasonic thickness...), but if by "WT" you are by any chance meaning the weight of the pipe (and while many types of at least steel or iron might really differ very little in wall density) I would add I'm not really sure how you would (non-destructively) reasonably determine the latter without some means of determining the wall thickness. One way of determining thickness is of course with reasonably calibrated application of ultrasonic thickness instruments (that as others have mentioned probably for this and other reasons should perhaps not be dismissed casually) .

 

[rconner]

[I guess same answer if "WT" refers instead to "wall thickness" ;.) ]

 

[BigInch]

Repeat. Check your design code. For example B31.8, unknown pipe is limited to 20KSI. What the fittings are stamped have no bearing on pipe yield strength.

I hate Windowz 8!!!!