Use of FRP pipes for compressed Air up to 25 PSI

[junaid70]

Hi,
Can we use FRP for compressed air ? If we can what is Max pressure for 4", 8" 10",and 12" pipes.
It a filament wound with vinelyester resin.
Thanks
Junaid

 

[TD2K]

Have you talked to vendors?

http://www.ifs-frp.com/PDFs/AirTestingBull.pdf

I would say from this the answer would be no. Note the attached link is discussing short term testing while you are proposing continuous operation at this pressure.

 

[SJones]

But that is a pressure test above operating pressure. For utility air, buried GRP would be a valid option. For above ground breathing air, it would not be. It's an expensive proposition over the normal metallic materials for this service.

Steve Jones
Materials & Corrosion Engineer

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

 

[zdas04]

I've used FRP up to 6-inch in ANSI 600 (MAWP 1450 psig) for methane service. I'm not real sure what your concern is.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[SNORGY]

I interpret from the safety bulletin that their primary concern is the release of stored energy in a failure during pneumatic testing (the first time the pipe is tested under pressure with anything).

I don't foresee anything that would prohibit the conveyance of pressurized air through fiberglass pipe.

 

[junaid70]

Thanks all for your input.
I am looking for ASTM /API/ AWWA/ ASME code that would give me the guidance on the FRP pressure rating for compressed air. In my process, pipes are pressurized for 35-45 minutes to check the integrity of modules for pressure upto 15-25 psi. I am trying to use 12" FRP pips.
The supplier is not sure for pipe air rating and i am only able find directives on HDPE API 15LE API 15HR not specifying any thing on compressd.

Thanks

 

[SJones]

A pressure rating is a pressure rating, not just for air in a pressure test. Air will not factor the design pressure downward from the rating achieved with water.

Steve Jones
Materials & Corrosion Engineer

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

 

[stanweld]

Some of the thin wall FRP that we have had to install in air service, both below and above ground, is an absolute nightmare. Damage (if one looks at it cross-eyed), and multiple repairs have virtually negated any positive benefits that I could see. There are other plastic materials specified for air service which we have installed that are much more resistant to damage.

 

[MJCronin]

junaid...

FRP piping acceptability for compressed gas applications depends a lot on the pressures involved and the location of the system.

Remember, compressed gas systems can detonate and FRP piping is brittle. Larger diameter FRP systems can store a lor of energy.

There are also fire protection issues. Metalic piping systems are much more resistant to failure than FRP systems in a fire.

ASME B31.1/B31.3 do not permit FRP piping used in explosive/dangerous compressed gas systems.

 

[junaid70]

MJcronin
I am trying to use FRP in waste water application for air only with pressure around 15 PSI . I have installed relief valves for safety. Pipes are designed for 9 Bar prssure . It is not a continous air service . Once a day we will pressurize the pipe for around 45 minutes.

 

[StevenHPerry]

Note of caution: other plastic pipe (HDPE) is sensitive to elevated partial pressures of oxygen over the long term. I do not know if FRP has the same concern, but I would check in to it if I were involved.

- Steve Perry
This post is designed to provide accurate and authoritative information in regard to the subject matter covered. It is offered with the understanding that the author is not engaged in rendering engineering or other professional service. If you need help, get help, and PAY FOR IT.

 

[moltenmetal]

MJCronin: unless I'm missing something, FRP piping is approved for normal fluid service per B31.3 unless non-approved components are used. Safeguarding may be required depending on the service, and of course client preferences beyond code also apply where required by contract. To my knowledge only PVC and CPVC are prohibited from compressed gas service per B31.3.

 

[MikeHalloran]

So far no one has mentioned the operating temperature, which has a strong influence on the performance of any plastic product.

Mike Halloran
Pembroke Pines, FL, USA

 

[MiketheEngineer]

Pick up that 2,000 lb phone and CALL the mfg!!

 

[MJCronin]

Molten,

Thank you, I stand corrected regarding FRP piping in flammable gas service for piping designed to ASME B31.3. It is my opinion that ASME does no favors to the journeyman chemical piping engineer with the hot mess that they call B31.3....

My older (2010) copy of ASME B31.1 in paragraph 122.8.1 (b) requires steel pipng for for all flammable gas service (with some exceptions for copper and seamless tubing).

As I recollect, the NFPA rules contain the same requirements for steel/metal piping in flammable fluid service

Junaid70..... I see nothing in either code that would prohibit your usage of FRP for compressed air

Best regards

 

[moltenmetal]

MJCronin: thanks for providing the reason to check the code to verify my remembrance of it.

I don't think that arbitrary prohibitions of piping materials or joining methods on a broad service class basis (certainly a service class as broad as "general fluid service" per B31.3) is doing any "journeyman chemical piping engineer" any favours.

There are applications where the fire risk associated with handling flammable materials in nonmetallic piping can be mitigated by other means, and where metallic piping (lined or not) is impractical, and where FRP piping is absolutely the best solution. A general prohibition wouldn't be appropriate. An engineer who doesn't know that the release of flammable material during fire is a serious concern in the design of any piping system containing combustible much less flammable materials, frankly shouldn't be designing piping, with or without the assistance of a code.

You are quite correct that other standards, some of which having the force of law in some jurisdictions, prohibit the use of nometallics in (certain) flammable services.

Codes are not intended to entirely replace professional engineering judgment and I resent it when people try to use them to do so. While I have problems with B31.3 just like you do, I doubt they're the same problems that you have with it.