vessel without proper construction tag 4

[sftyvlv]

Hi folks:
I've seen this before but hadn't thought much about it because nobody seems to care.
Having said that, on several occasions I've seen in use a compressed air manifold with a receiver, with 8 outlets on it or so.
Upon further investigation, noticed no construction tag on it and nothing pertaining to material(thickness) used ,mawp,mawt, not even a pressure guage or safety valve.
I have seen this practice done on other jobs.Is this legal and if not should I contact our regional boiler inspector? Thanks
Dave

 

[JStephen]

It may qualify as a piping component rather than a pressure vessel.

Not all jurisdictions regular pressure vessels, as far as that goes.

 

[GenB]

5 in pipe or below needs no certification, so there is your answer, if 6" ID or higher, you can report it and they can et nailed.
that is if the pressure exceeds 15 psig.

 

[racookpe1978]

Permanent part as a pressure vessel or piece of piping, or a construction (temporary service, ambient temperature) 100 psi air header?

 

[Duwe6]

If it is made of pipe & pipe components, and doesn't 'contain' anything, i.e. it is used as a supply manifold, it can be classed as "Pipe". If operated under 150 psig, call it "ASME B31.3 Category D" -- no RT or other NDT required. The welds do require a Visual Inspx.

 

[sftyvlv]

This vessel would be your typical "air pig" style receiver/manifold and yes it was constructed of 6" or larger pipe and yes I believe it carried over 100 psi compressed air. It's connection to plant air is from compressed air hose and "chicago" type coupler.
I see this all the time in many industrial settings and just shake my head.

 

[Duwe6]

Why a headshake? 6" Sch 40 seamed pipe, by B31.3 Code is allowed a WORKING pressure of about 1500 psig [not 150, 1500]. If the welds on end-caps on the air manifold have absolutely no root penetration, that still gives a safe load od 750 psig and a Burst Pressure in the 3000 psi range,

All this assumes no internal corrosion, but it would take a lot of rust to bring Tmin down below 200 psig. P*D / 2SE gives a Min Thickness of .039" for a 6" A53ERW pipe at 200 psig. Pipe is VERY strong. If it is well supported, if all the fittings are welded, if there are no valves, etc.

 

[sftyvlv]

Duwe6, I am aware of this and that the poorest weld may infact hold indefinately. My point being that this vessel was not constructed to code and if in fact it need be whats to stop anyone else from fabricating whatever they want with whatever material they want and weld it anyway they want. The code must be followed.

 

[Duwe6]

Still not a vessel. It is a pipe manifold, distributing a B31.3 Category "D" fluid -- compressed air at less than 150 psig. Cat. D only requires a visual inspection - VT of a low percentage of the welds, and an Inservice-Leak Test. No RT or Hydro required. Other than not documenting the VT & ISLT, they are in compliance, at least for the USA. DIN/ISO may vary.

 

[jte]

sftyvlv-

I find it interesting that you started the thread with a question. Now you are arguing a position. It would appear that you are trying to gain support from this site to settle an issue which you have started at work. As the responses were not to your liking, you became argumentative.

piping components, such as pipe, flanges, bolting, gaskets, valves, expansion joints, fittings, and the pressure containing parts of other components, such as strainers and devices which serve such purposes as mixing, separating, snubbing, [highlight]distributing[/highlight], and metering or controlling flow, provided that pressure containing parts of such components are generally recognized as piping components or accessories;

It seems that nobody would argue that this air pig is distributing flow. So the only remaining issue is to determine whether it is generally recognized as a piping component or accessory. Given that everybody else recognizes this as a piping accessory, I think the case is closed.

But by all means… Go blow the whistle to the regulators. Let us know the results of the investigation.

jt

 

[vpl]

jte,

Star for you for expressing my thoughts as well. If sftyvlv believes there is an issue, then he shouldn't argue it here, he should report it.

Patricia Lougheed

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Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.

 

[sftyvlv]

To All:
I'm very sorry, I did not intend to argue this question, your expertise is highly valued and I do not mean to upset anyone.
I have seen "air pig" style manifolds from a manufacturer with a "U" stamp and tag verifying the specifications I first listed. I assumed a "backyard" manifold would not be allowed where employees or the general public are exposed to it.

 

[jte]

No problem. I agree that a "backyard" manifold would expose an employer to some liability. In the plants which I support, I would expect such a critter to be designed and fabricated in accordance with B31.3, but not Section VIII. Some engineering design oversight and fabrication oversight is necessary for an employer to pass the "red face test" if an incident were to occur. Also, let's not forget occasional inspection. If these are used primarily on shut downs, then stored, the likely time to inspect would be about a week before the shutdown.

jt

 

[celeronsean]

Ok, let's say that the vessel is much larger than 6" ID (30" for example) and holds a pressure of 100 psig. Would the "air pig" vessel need to be properly tagged and designed according to Section VIII?

 

[jte]

celeronsean-

It is a function of function. Regardless of size or pressure, is the 30" pig still serving in one of the functions in the quote in my post of 10 Nov 13:23?

Unless you no longer use the equipment for distributing, then it would still likely fall under one of the B31 or other national piping codes. Not a vessel.

jt

 

[Duwe6]

Usage such as retaining compressed air, i.e. "air bubble" protable supply of compressed air does indeed fall under Section VIII. The cut-offs for vessels are below 15 psig, diagonal ID measurement less than 6", etc. Normal usage defines proper Code.

 

[celeronsean]

Thank you Duwe6 and jte for clearing that up. I can see the use of the vessels in question as a distribution system, also the vessel to which I am referring is not used as a portable compressed air system. It is merely a means to distribute and offer volume to reduce fluctuations in pressure changes.

Thanks