Prohibition of Reinforced Thermoplastic Pipe for Offshore Pipeline (Liquid & Gas Hydrocarbon)

[ek4putr4]

Refer to ASME B31.4 Chapter IX section A423.2 and ASME B31.8 Chapter VIII section A811, is there any reason why plastic pipe with non metallic reinforcement such as RTP pipe is prohibited to be used for offshore liquid pipeline system under ASME B31.4 or for gas transmission line under ASME B31.8?

 

[stanier]

One should perhaps consult ISO 14692 Petroleum and natural gas industries —
Glass-reinforced plastics (GRP) piping. Or Det Norske standards such as

http://www.google.com.au/#hl=en&tbo...bd62e69f0feaab&bpcl=39650382&biw=1229&bih=617

“The beautiful thing about learning is that no one can take it away from you.”
---B.B. King

http://waterhammer.hopout.com.au/

 

[ek4putr4]

Please be focus on "thermoplastic" pipe with non meyallic reinforcement, called RTP.
Flexsteel product is flexible pipe with steel reinforcement, and fiberspar or any GRP product is thermoset pipe. Both ar not my interest in this discussion.

 

[zdas04]

RTP is not a term I am familiar with. I will stop trying to contribute to the discussion.

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.

 

[patprimmer]

RTP is reinforced thermoplastic, like polyethylene, polypropylene, polycarbonate, nylon acetal ABS and some polyesters and some polyurethanes. There are a lot to many to list. The reinforcement is most often short glass fibres, but can be long glass via a quite expensive process and can be many other fibre types like carbon, aramid, wollastonite or even stainless steel.

Fiberglas is reinforced thermoset plastic like two pot polyesters or epoxy or urea, melamine or phenol formaldehydes. Rubber is also mostly a thermoset unless otherwise specified.

Regards
Pat
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[zdas04]

I've called that FRP (fibre reinforced plastic) for 25 years. Guess I was wrong.

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.

 

[stanweld]

Amending Codes, especially when the amendment is perceived as "loosening" restrictions, is quite difficult. Code participants are much more willing to increase restictions when evidence warrants. Code participants may have rooted opinions, often justified; adhearance to the status quo is often more preferable. There may also be legal (perceived liability) issues when Codes are adopted by Jurisdictions should catastrophic accidents occur.

 

[Taz99]

You can have a look at what Airborne are doing with RTP pipes.
For some short words on their qualification approach check out

http://www.airborneinternational.co...ation&page=detail&catid=34:oil-a-gas&Itemid=2

"Because no specific (ISO or API) standards exist for composite pipe systems, the approach is followed- as described by the DNV Recommended Practice for New Technologies, DNV RP-A203, and DNV OS C501 for designing in composite materials."
They are putting a lot of money into their second manufacturing facility to substantially increase their capacity.

 

[patprimmer]

David

Technically your not wrong. It is fibre reinforced plastic, but the industry in its ignorance has always reserved FRP for traditional fiberglass of very long glass fibres layed up with a thermosetting resin, most often two pot polyesters, but also epoxy or others.

Short fibre reinforced, like 1mm long or less in a thermoplastic resin is called RTP or just glass filled nylon or whatever resin. Different people tend to use different terminology ranging between glass fibre reinforced to glass fibre filled to glass filled.

Other fibres like carbon and mineral fibres further confused terminology as does different polyesters simple being referred to as polyester and fillers other than fibre being used.

I gave up years ago trying to introduce logic and accuracy to it.

Regards
Pat
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[rconner]

Huhhm, modern “codes”… Back in an era when I suspect metals e.g. iron were at least as valuable or precious as they are now, and buildings/houses were largely non-metallic logs or wood, I believe e.g. one quite bright American wrote about 260 years ago (in Poor Richard’s Almanac) that one should use some of it quite strategically,

“How to secure Houses, &c. from LIGHTNING”:
“It has pleased God in his Goodness to Mankind, at length to discover to them the Means of securing their Habitations and other Buildings from Mischief by Thunder and Lightning. The Method is this: Provide a small Iron Rod (it may be made of the Rod-iron used by the Nailers) but of such a Length, that one End being three or four Feet in the moist Ground, the other may be six or eight Feet above the highest Part of the Building. To the upper End of the Rod fasten about a Foot of Brass Wire, the Size of a common Knitting-needle, sharpened to a fine Point; the Rod may be secured to the House by a few small Staples. If the House or Barn be long, there may be a Rod and Point at each End, and a middling Wire along the Ridge from one to the other. A House thus furnished will not be damaged by Lightning, it being attracted by the Points, and passing thro the Metal into the Ground without hurting any Thing. Vessels also, having a sharp pointed Rod fix'd on the Top of their Masts, with a Wire from the Foot of the Rod reaching down, round one of the Shrouds, to the Water, will not be hurt by Lightning.”

While I guess even our precocious Ben Franklin may not have precisely understood then the integral calculus/electrical engineering involved in structural damage to building materials by lightning (i.e. by deposition of thermal energy, ∫ i2Rdt ), he did understand lightning could and occasionally would hit (or ignite or blow holes in!) virtually anything/material, and he eventually also knew as long as you didn’t have “ahold of” same at the time it would do less damage when it could run down his conductive invention. In the centuries since (and whether or not it has been understood or appreciated by those of us with a great many IQ points less than ol’ Ben), all manner of structures, be they homes, factories, refineries, platforms, or whatever have of course subsequently been provided with sorts of metal skeletons or exo-skeletons in the form of metal eaves, vents and downspouts, metal beams or other building materials, or if not anything else at least sturdy metal water and gas pipes going to many rooms (with same often transitioning far into ground) and indeed copper wiring if not specific lightning rods and grounds etc. I guess this traditional infrastructure has sort of kept us in general pretty safe for a very long time, regardless of exactly how it was done, who did it, or whether it was exactly “up to/per” any code. I think some standards e.g. API RP 2003 -- Protection Against Ignitions Arising out of Static, Lightning, and Stray Currents to their credit at least up until a very few years ago if not currently contained some guidance statements e.g. to effect, “Metallic tanks, equipment, and structures commonly found in the petroleum industry that are in direct contact with the ground (i.e., no nonconducting membranes) have proved to be sufficiently well grounded to provide for safe propagation to ground of lightning strokes…” and at least with regard to tanks, “It is not recommended to store flammable liquids in nonconductive (e.g., plastic, fiberglass) aboveground tanks.”

Now, some modern science and “technology” thinks they have a better idea, i.e. go increasingly toward such things as non or less-metallic “flexible” pipes or composites, that the pipe pushers or developers claim can be installed at less cost, will do the job, or may even have other advantages over sturdy and more conductive and more heat-resistant metals - “Plastics my boy, plastics”! Now while I think most contemporary specifying Engineers (and Regulators) understand that plastic pipes are not really near as strong as traditional metal pipes, they may not be aware of many less obvious shortcomings and they can additionally be sorely tempted (or blinded?) by the lure of lower material prices, alleged cheap installation costs or other claimed advantages, and/or other pressures so to speak (and many succumb).

While it is bu tone of many issues, since ancient times lightning has traditionally been considered an “Act of God” (or hurled down from the hand of gods?), it appears vulnerability to same can be increased by some choices of Man. You will notice that very quickly if you e.g. do a Google search with the keywords, “lightning strikes plastic gas pipes”, that many unfortunate (and surely unintended?) events over the last few years e.g. were really foretold long ago, e.g. in the article also near a quarter century ago at

http://www.jlconline.com/Images/Lightning Protection Primer_tcm96-1149132.pdf,

“Whenever you substitute plastic piping for metal or use electronic
devices, you increase a building’s vulnerability to lightning currents.” And then there are also some rather non-obvious static electricity effects with non-metallic gas and fuel pipes and containers (not discussed by this particular author). I guess if one is dead set on installing mostly non-metallic pipes etc. as opposed to legacy metals, it seems a complicated business to protect same and one might want to find an overall designer smart enough, and a suitably trained installer also smart and conscientious/honest enough, to design, build, and stand behind a reasonably safe outcome, and be sure to figure all costs of same in to any material comparisons, lest this “strike” (so to speak) close to home. That apparently been some difficult to find/obtain in at least many areas of at least 12 states. Everyone have a good weekend.

 

[patprimmer]

Good grief. That was a hell of a novel to simply say substituting plastics might increase damage from a lightning strike.

Even then you forgot to mention if the installation is indeed subject to risk of a lightning strike, as I have yet to witness the lightning strike a cable laid deep on the ocean floor.

I am aware that lightning strikes can damage cables buried in the ground and in fact high dielectric reinforcement of optical fibre cables can in fact reduce risk of damage from lightning.

I certainly know that at least one manufacture of aramid fibre has a technical bulletin discussing the concequences of lightning strike when aramid replaces steel reinforcement.

I also know aramid fibre reinforcment has been successfully used in applications where steel failed due to lack of strength.

Regards
Pat
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[BigInch]

Explosive decompression is another "worry". High pressure gas dissolved in the plastic can be explosively released from the wall if the pipe is rapidly depressurized.

"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek

 

[zdas04]

I've seen explosive decompression, but only in a phase change scenario (e.g., CO2 at 80F and 10,000 psig is dense phase and that is what absorbs into the plastics--when you depressurize the line the dissolved dense phase stuff explosively becomes gas and shreds the plastic). I have never seen it in FRP, and I haven't used RTP.

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.

 

[patprimmer]

I believe it is feasible with either material under certain conditions.

Also plastics have a very narrow good temperature window for use compared to metals.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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[ek4putr4]

To BigInch,

Is there any records/statistic of failure of RTP/FRP/GRP for onshore application due to explosive decompression?

 

[BigInch]

As it is prohibited, I would assume offshore records are nonexistant. There may be some onshore, or perhaps some test data. All I know is that it is believed to be susceptible, since gas has supuposedly permeated into the reinforcement layers. Its history of use onshore is not long either.

"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek

 

[hathib]

hallo guys,

im new kin in the block...just wonder if any of you have experience in RTP subsea installation. Maybe you can share some as im going to involve in mentioned job. Fyi, the job concept is insertion whereby originally 12" pipe of crude will be decomm and RTP of 3" will be insert into the pipe.

Looking forward your expertise.

 

[BigInch]

hathib, start a new thread.
You might want to give a much better explanation of what you're trying to do too.

Independent events are seldomly independent.