Calibration loop spools for internal use 1

[Clareok]

We have a pressurized calibration loop where we want to reduce cost for spool sections. We want to be in compliance with B31.3 generally.
As we need to have inner diameter to a certain dimensions (8" sch 40), we can get 2 or 3mm plate rolled to this ID.
To be in compliance with B31.3, do we need to complete xray etc.. or as this is for internal use, would SEP be sufficient & a final hydro test be sufficient?

 

[XL83NL]

Since you mention SEP, I assume you're located in the EU, this piece of piping falls under the PED 2014/68/EU, and is subject to cat O, module 'SEP'. Correct?

Huub

 

[Clareok]

Correct, we are in the EU. We will not be putting this on the "market", therefore i dont believe it needs CE marking.. its for internal use only.

 

[XL83NL]

Correct, my understanding of the PED as well. CE-marking does not apply, hence the ESR's don't need to be fulfilled. Nevertheless, I would want to do some sort of testing( ah ydro, maybe and RT or 2), depending on the application, the pressure applied, etc. Why not take commercial 8" Sch 40 pipe, instead of rolling it from plate? Or did you meant to say you need 2-3 mm wall thickness instead of 8" Sch40?

Huub

 

[Clareok]

Totally agree, in that we intend to hydrotoest. The reason we want to roll pipe is to save money. As its a calibration loop, the ID is critical. Typically need the ID of 8" sch 40 but that is very expensive in 304ss. We can get the same ID from formed pipe (rolled or folded) making it alot cheaper.
We have also designed interchangeable flanges for different rating 150, 300, 600 etc, very special flanges and to go try evaluate these by calculation would prove very difficult.

 

[EdStainless]

You can get a piece rolled and welded, 100% x-rayed and hydroed for less cost than buying a piece of pipe? Seriously?
Besides what do you use for the ID size of pipe?
The wall tol is -12.5%/+25% (and there is an OD tol) what size do you use?
Stainless pipe is so common that you can probably reach out to a stockist and buy short pieces if that is all that you need.

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P.E. Metallurgy

 

[Clareok]

8" Sch 40 has an ID of 202.74mm, so we can roll 2/3 plate to this ID +/-, but a close as possible to this. Agree you state the mill tolerance, but we try to get close to the theoretical.
6m of 8" sch 40 304ss is approx €5k. We can get this rolled and welded for fraction of this (welder not code certified, no NDE except hydrotest). so that we why im asking.. do we need to complete Welding/NDE per B31.3 as this pipe work is for internal use and not being sold.
Ultimately we need this to be safe so i feel a final hydrotest is sufficient, but want to ask the question.

 

[LittleInch]

Well it's up to you really IMHO.

Your risk is that you do the welding using some unknown untested welder using unknown welding techniques and unknown welding consumables to weld up your hopefully round pipe which when you only hydro test to ?? barg, it then fails under test or worse, passes the hydro, but has underlying welding faults which only appear once it's been fatigued a few times.

Or it fails in service after a few days spraying whatever your pipe contents are all over your personnel. Your personnel then sue you for millions based on you trying to save € 2-3,000 because you didn't follow the established "rules" for pipe manufacture, testing and design.
Your insurance company abandon you as you didn't follow the rules.

B31.3 is there as a guidance for safe practices and this has zero to do with whether you sell this as a product or not.

So the key thing, IMHO, is:

I initially missed the bit about your "special flanges". Now that I would like to see.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Clareok]

Thank you all for your input, its always good to hear from like minded ppl.
Design pressure of the pipeline is 12 bar, hydrotesting to 18 bar. I wonder what the worst failure could be, assume a dribble leak, or could there be a major blowout occur.. i dont know.
The special flange is real piece of water cutting (from 30mm) - alot of material removed - impossible to try verify by code calculation i would think - we could run some FEA on this in Autodesk inventor as a basic check.
I think we could get welded by a coded welder in accordance with a certified WPS/PQR & maybe complete some spot x-ray with a final hydrotest, without adding too much cost.
We might just have to check with the insurance company.

 

[danschwind]

Why do you need that specific I.D.? What is the fluid?

Daniel
Rio de Janeiro - Brazil

 

[LittleInch]

Well if this seamed pipe it could be anything from a pinhole "dribble" to a jet of ?? to complete unzipping of the weld.

Think the cost might suddenly go up a bit when the fabricator needs to adds cost to the welding and get some inspection team in rather than getting the apprentice to do some practice on stainless steel.

I do wonder / worry about this multi dimensional flange and how something quite big and heavy is actually connected to a pipe only 2-3mm thick.

12 bar is no laughing matter. I just can't see the cost benefit here.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[danschwind]

Regarding the flanges, I would use a lapped flange arrangement.

Daniel
Rio de Janeiro - Brazil

 

[EdStainless]

In the US a 20' length of 8sch40 304L welded pipe is about $2500.
Call someone that you know at an equipment fabricator and ask them to get you a price, and buy a piece for you.
You might be able to make a deal with them and buy a shorter piece that they want part of.
The ID size on commercial 8sch40 is +/-7%, don't try to rely on dimensional accuracy.
And actual typical pipe that you buy will have an ID of 203-205mm, mills always want to make the wall thin to save metal. Unless of course they had a mess up and send you something on the heavy side just to get rid of it.


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P.E. Metallurgy