Pig Launcher Design Code 1

[91873634542]

Hi All,

i have a case when fabricate Pig Launcher.
actually, our function only fabrication service exclude design and engineering.
we are fabricating Pig launcher 14" X 12 " and when fabrication finish we are ready for precommisioning.
my responsibility is doing flange management and hydrotest.
i am surprise when read the drawing that design pressure is 3705 Psig and hydrotest pressure is 5550 Psig but using flange 14" #600.
as i know, maximum allowable pressure for this rating is 2225 Psig.

i want to ask :
1. as we know that pig launcher only for transfer pig from barrel into pipeline / piping system, can we make hydrotest pressure only half from operating pressure or at least same with operating pressure (3705 Psig) ?
2. what code for design code ? ASME Sect VIII Div.1/2, ASME B31.8, or ASME B31.3 ?
3. anybody can help explain for my case ? i know our client consider about cost

regards

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[C2it]

This reads like an accident looking for somewhere to happen.

What steps to take ?

Big ones.

 

[zdas04]

The MAWP of a system is the lowest MAWP of any component on the system, so if you build the pigging facilities to ANSI 600 class then the system cannot have a higher MAWP than the launcher/receiver MAWP (unless you put a positive spec break on the launcher/receiver somewhere, but I don't know a reasonable way to do that).

I build pigging equipment on gas gathering/transmission to ASME B 31.8.

There is a communication disconnect in your case between the gathering system description and the pigging facility description. I'd fix that before I spent any money.

David Simpson, PE
MuleShoe Engineering

Law is the common force organized to act as an obstacle of injustice Frédéric Bastiat

 

[LittleInch]

The design information is clearly wrong, which you need to point out to the designer / client in writing. Either the flange rating is incorrect or the design and test pressures are incorrect.

For your questions
1) No, the pig trap is part of the pipeline and needs to conform to the same design and test pressures
2) The pig trap should be designed and built to the relevant pipeline code (31.8 in your case), not 31.3 or ASME VIII which will give much thicker wall / smaller ID for no benefit and actually make the pig trap difficult to use.
3) See above - there is an error which it is your duty to point out to the client and await further instruction

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[BigInch]

You would be best advised to refuse to build this trap until you have clarified the situation. Given what you (think) you know now, to fabricate it knowing that it will probably be operated in violation of design conditions, you'd do best just to walk away, or you may be found liable if an accident were to happen at anytime in the future.

I hate Windowz 8!!!!

 

[Duwe6]

". . . you'd do best just to walk away, or you may will be found liable if an accident were to happen at anytime in the future."

Fixed that to reflect the current state of USA jurisprudence. You have now, by your written statement [above], noted that there is a Design mistake/miscommunication/spec typo. To procede after having pubically noted this condition makes you [among others] liable. And when I write 'you', I mean you personally, not just the company you are working for.

Happy, Happy . . . .

Welcome to the Big Leagues I really do mean that - you could not get into this position if you were 'just a little worker bee'. With authority comes responsibility.