GRP Piping For Breathing Air 1

You might want to check if and how NFPA standards are implemented in local regulations, such as the following at Newport Beach, California in regards to breathing air supplies.


· Tubing shall be stainless steel complying with ASTM A269, or other
approved materials that are compatible with breathing air at the system
pressure.
· Routing of tubing and bends shall be such as to protect the tubing from
mechanical damage.
· Fittings shall be constructed of stainless steel complying with ASTM
A479, or other approved materials that are compatible with breathing air
at the system pressure.
· The use of nonmetallic materials, carbon steel, iron pipe, malleable iron,
high-strength gray iron, or alloy steel shall be prohibited for breathing air
pipe and tubing materials.

NOTE THE REQUIREMENT FOR 5000 PSI,




"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein

Uh, "otherwise taint" might include release of glass fibers, e.g. from cut ends. I personally wouldn't want to breathe it.



Mike Halloran
Pembroke Pines, FL, USA

Exactly Mike, you can see that in most of the breathing air equipment standards and medical air piping systems that, in addition to the control of intake quality, avoidance of all types of foreign matter, rust scales, powders, particles and fibers is obviously of paramount importance and the piping material recommended for such sytems is not usually going to contribute to that load. Most even avoid threaded joints due to the hazard of a stripped thread getting picked up and delivered to the consumer.


"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein

Let's not forget about the vapours from the resins- these don't dissipate quickly. I have no more desire to breathe styrene than I do to breathe glass fibres...

Good points of conjecture versus actual experience leading to the supposition that there is no experience because nobody wants to examine the actualities of such systems. Oh well - looks like the 'certified' thermoplastic pipe will win out and we'll hope that none of the constituents diffuse out!

Steve Jones
Materials & Corrosion Engineer

I would suppose that that supposition is not entirely valid. There are a number of standards in common use concerning this topic which (I would suppose), as have most standards, been derived from years of experience. Besides the simple fact that after a few years most Glass Reinforced anything I've seen gets to looking pretty ragged around the edges with particles of glass fibers readily visible enough to where I certainly wouldn't want to be depending on that material for a supply of breathing air.


"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein

Our piping spec for breathing air states that all materials and fabrication will comply with ASME 31.1. It specifically calls out 316L SS mill certified for O2 service.

There is also an added comment that Galvanized Pipe shall not be used in any part of the system, peroid.

Our plant wide system is now all 316L with brass/ss quick connects with hose break valves.

The comment on galvanized pipe came from us getting in trouble as several checks on filter sampler revealed traces of lead above the permissible level.

Big Inch - a search on IHS using 'breathing air' brings up 547 hits. Having sampled a large number of these hits, I'm still not seeing one that prevents the use of GRP. In the quoted Newport Beach example, it's not surprising that GRP is a non starter at 5000 psi. As to glass, well there are filtration systems that can be placed in both the piping and the breathing masks (don't forget that filters would also have to take oil droplets out of the system from an oil lubricated compressor). I would also take issue on the appearance of GRP since I've seen it pulled out of liquid hydrocarbon service after several years and it looked pretty reasonable to me. Styrene, although not nice, is also not totally prohibitive - take a look at UK HSE's allowable limits for workplace exposure (EH40) and then apply the requirements of BS 8478 Spec For Diving Gases (10% of HSE limits) and there is still a possibility also taking into account that the required service is totally for emergency, temporary refuge scenarios after a major H2S release (we don't plan on having one of those every week!). Syd's experience is noted - unfortunately we do want to avoid metallic materials because the pipe will be buried and we don't want coating and CP issues. All in all - I guess it will boil down to trying to obtain an ISO 15001 report for the thermoplastic and having the material and installation comply with the AGA Plastic Pipe Manual.

Thanks for all your contributions.

Steve Jones
Materials & Corrosion Engineer

I would expect your company's lawyers would have a heart attack if they saw you were deviating from Best Practices for a life safety system like this. What is your motivation for the using the GRP? Overwhelming cost advantage? Whether or not it might be suitable, why take a chance on such an important system?

That's exactly what I was trying to imply. Hopefully there will be a chief engineer in the chain before it gets to the lawyers. Experimenting on live human subjects in an industrial environment is frowned upon these days, especially in the case where recognized standards exist that were not followed.


"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein

Errr guys - what part of 'looks like we will be using thermoplastic pipe' did you not understand? And, before you fall off your 'best practice' and 'established standards' hobby horses, the desire to use thermoplastic pipe comes from a world reknowned breathing/medical system supplier. I wish you a Happy New Islamic Year!!!

Steve Jones
Materials & Corrosion Engineer

No worries. Wouldn't be the first time I said NO to a vendor.




"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein

Would you ever say yes if the correct data was put in front of you?

Steve Jones
Materials & Corrosion Engineer

SJones:

You're using an on-line forum and we're trying to be helpful to you. You should not be surprised to get some opinions which you feel to be "unqualified"- you're the one asking the question here instead of at ASHRAE or some association of industrial hygienists etc. which specialize in the topic at hand. Most of us come here to learn and to be helpful in whatever way we can as a means of recompense for what we've learned.

I hear you about the "best practices hobby horse". Too many engineers use codes, standards and company procedures to avoid doing any engineering whatsoever. Ignoring the standards and proceeding blindly is more dangerous still, but the use of standards as a crutch by engineers drives me nuts. Standards should be written to give design guidance to engineers rather than trying to provide a perscription to non-enigneers of how to do an engineer's work which then PRECLUDES the use of engineering to obtain a more optimal solution. Merely reading and applying the corporate standards is sensible I guess if that's what you're being paid by your firm to do, but it's a real PITA when you come across a situation clearly not anticipated in the standards and all the helpful advice these standard-slingers can offer is, "Tell me where in the standard it says you can DO that!".

I've never had to design a multi-user breathing air system so I've never reviewed the standards. In your review of applicable design guidance (ie. as opposed to the Newport Beach thing which is clearly for filling SCBA tanks), are point of use filters for oil and particulates actually permitted? The only supplied air systems I've seen had no point of use filter in the mask etc. I thought that you had to use oil-free compression equipment or to do a scrupulous job of removal of oil and organic vapours etc. at source, plus pre-cleaning of the piping so that point of use apparatus needed no filters, but that may only be for systems that are engineered for single users.

I see no reason that FRP pipe could't be properly precleaned of particulates including glass fibres, but it would take a long time for enough styrene to out-gas to a level where it was no longer detectable. The same would definitely be true for PVC or any other solvent-cemented product, but would not be true for a thermally welded material like HDPE. If the compressor is running continuously and venting the air through all the branches of the distribution system continuously, then the accumulation of solvent/monomer vapours would not be a concern. If the unit is shut down and only operated when required, the pipe would be full of styrene or other monomers for the first (considerable) while due to out-gassing.

Using non-engineers to do an engineer's work defeats "engineering" no matter what standard is or isn't followed, just as badly as using engineers inexperienced in the application of a particular code or standard. There is no code, standard or regulation that can apply blindly to all cases. For that reason, there are many of each of them and often specific methods for obtaining variance when required. Furthermore, if such is the case, and competent supervision in the matter at hand is not available, not sought when not available, or presumed competent advice when found is ignored, one would think that the "responsible" designer would then either determine that the standard does not apply to the case at hand, assuming s/he had the knowledge or experience to make that determination, or alternatively, request exact clarification of applicability of the standard and the manner in which the standard should be implemented in the specific design in question from the issuing authority and follow such advice when received. To do otherwise not only defeats the purpose of "engineering", and the code, standard, or regulation, but also deprives the designer of the considerable experience compiled in the making of the document, potentially precludes the owner of receiving full benefit of requesting an engineer to design the product, and quite possibly endangers the end user, and in actually demeans the entire profession.

I'm not telling you what to do, just suggesting what some accepted practice may be in some areas, offering an example of the extremes that might be legally required, urging you to check your local laws and regulations (if there are any) and lastly, not blindly accept some vendor's advice (is he the engineer or you?), before you decide to do whatever ou think is the "right thing". Nothing more and nothing less. I never try to make the horse drink the water, unless that horse is working for me.



"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein

Very good points and good debate about 'engineering' and the use of forums. Of course there will be differing opinions and there is also the aspect of devoting sufficient time to formulating questions and answers. Thank you to molten for taking some more time than usually warranted to chip in and actually get down in writing precisely what was running through my head. There is also the case for actually quoting standards when making statements and also trying to avoid inflammatory intonations. Ultimately, it boils down to: there is a standard for the air and the system has to deliver air to that standard using materials that are 'acceptable' as judged by another standard. My thrust was in trying to find out whether anyone had already gone down the road of proving (or disproving) GRP as acceptable or not principally because we are far far more experienced in the design and installation of GRP systems than we are for thermoplastics and we don't want the situation of having the design and installation let us down.




Steve Jones
Materials & Corrosion Engineer

Then in closure I'll simply mention that in ten years of experience in underground petroleum storage system and associated support equipment design, specification and installation, including breathing air for long term survival, entering and cleaning storage tanks, tunnel maintenance and emergency stations, anything outside of a few limited sanitary water drains did not [to my knowledge] contain a single piece of GRP. The installations were not legally or otherwise subject to ANY particular code, standard or regulation other than what was agreed with the client's engineering staff.


"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein

Big Inch - we've got many inch-kilometres of GRP pipe in all types of service (how about 120 bar multiphase 7-inch pipelines for one?) since the early 90s but we've never had to put in a breathing apparatus system before. It wasn't planned on the project and is a late addition so we're in a bit of tight spot timewise.

Steve Jones
Materials & Corrosion Engineer