Stamp "U" pigging trap end closures 4

[Stressero]

Good afternoon,

I have a question about whether to use "U" Stamp on pigging trap end closures. In according to UG-35 Other types of closures in ASME SECTION VIII-1:2017:

UG-35.2 Quick-Actuating Closures
(c) Specific Design Requirements
(2) The design rules of Mandatory Appendix 2 of this Division may not be applicable to the design of quick actuating closures; see 2-1(e).

Therefore, it is necessary according to the CODE that end closure with its hinge tap should be stamped?

thanks

 

[zdas04]

The decision is not whether or not to stamp the closure, the question is whether the pig trap is a "pipeline accessory" (not subject to the BPVC) or a "pressure vessel" (subject to the BPVC). By the definitions in the BPVC and in ASME B31.8 (and B31.3) the pigging equipment is a pipeline accessory and not subject to the CODE (as you put it, as though there were only one code). At least that is the way I've designed and built pigging equipment on 5 continents.

[bold]David Simpson, PE[/bold]
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

 

[dik]

Is it possible that a pig trap be spec'd as a pressure vessel and not an accessory? and how far apart can pig traps be located in normal practice?

Dik

 

[LittleInch]

I'm with zdas04 100% here

Is it possible to build it as pressure vessel - of course it is. it's the wrong solution and creates all sorts of unnecessary complications in design, construction and operation, but has been done, usually by piping designers who know no better rather than pipeline engineers who do...

how far apart? - Basically as close as you want to allow the doors to open and get access for valve operations etc. I've seen twin traps side by side with about 1D between them, but normally it's an access issue so 1m / 3 ft minimum?

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

 

[LittleInch]

E.g. ASME B 31.4 states for the closures,

"Quick-opening closures shall be equipped with safety
locking devices in compliance with Section VIII,
Division 1, UG-35(b) of the ASME Boiler and Pressure
Vessel Code."

In general the entire design of the end closure is normally specified as being designed to ASME VIII, but not stamped as such.

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

 

[dik]

Designed as a pressure vessel, are they less likely to leak? or, are both pressure and accessory not likely to leak?

Dik

 

[LittleInch]

Neither will leak if designed and constructwd properly.

PV will be thicker, more expensive and cause problems with ID compared to the pipeline.

Don't do it.

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

 

[dik]

wasn't going to... I was just curious... thanks very much.

Dik

 

[Stressero]

You are true experts, receive my thanks
zdas04
dik
LittleInch
You have clarified my mind ... Thanks!

 

[dik]

Not an expert at pipes... learning a bit as I go along. Six months ago, I'd never heard of a pig...

Dik

 

[zdas04]

I must be an expert, I wrote a book and got it published, only "experts" can do that, right? All joking aside Stressero, this is the kind of question that I try very hard to answer in my book, along with some perspectives on how we got to the point we are currently at. Pigging equipment is discussed in Chapter 6 that can be purchased individually at the hyperlink.

[bold]David Simpson, PE[/bold]
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

 

[Stressero]

More merit for you friend dik!

 

[Stressero]

How good! thanks for the reference friend David!