ASME U stamp requirement for quick end closures of launcher and receiver 3

[carlo1023]

Client datasheets for launcher and receiver require quick end closures having an ASME U stamp requirement. I would like your opinion on the following points below?

(1) Why is ASME U stamp required for quick end closures?

(2) If ASME U stamp is required for quick end closures, does it follow that launcher and receiver shall also be U stamped?

(3) If you weld a U stamp quick end closure to the launcher and receiver major barrel (launcher and receiver don't have U stamp), will it invalidate the U stamp of quick end closure?

Thanks.

 

[Mechomatic]

I am not an expert when it comes to ASME B&PVC, but my understanding is:

(1) Just because something doesn't technically fall under the "pressure vessel" definition as indicated in Section VIII, Div. 1, doesn't mean it can't be fabricated to those standards and U-stamped. I would have to sit down and look through Section VIII to tell you precisely if it is or is not considered a pressure vessel by ASME, but either way it can be fabricated and stamped in accordance with the U-stamp requirements. If it is not technically a pressure vessel, then my reaction is, "If the customer wants to pay for it, then that's just fine."

(2) I don't know enough about that to give you an educated answer, other than: If the lanucher/receiver is NOT considered a pressure vessel under Section VIII, then it being U-stamped is not required by ASME. U-Stamped vessels are connected to unstamped piping, and I am unaware if there is any rule that would apply to this differently.

(3) If you make any material change to the pressure-containing material, the U-stamp is voided. Period. I believe even just tack welding a support on to a pipe after it had been inspected and stamped would void the U-stamp, let alone welding a whole addition to it.

 

[carlo1023]

Thank you for your response.

The end closure is designed as per ASME Section VIII Div 1 while the launcher and receiver are designed to ASME B31.8.

 

[BigInch]

For B31.8 design you do NOT need a stamp on the closure, although many companies and their standards seem to think that they do, or know they don't but want to pay for one anyway.

Presuming you are designing a gas pipeline to B31.8,
Traps and Launchers are part of the pipeline thereby included within the scope of the B31.8 code.

803.1 pipeline: all parts of physical facilities through which gas moves in transportation, including pipe, valves, fittings, flanges (including bolting and gaskets), regulators, pressure vessels, pulsation dampeners, relief valves, appurtenances attached to pipe, compressor units, metering facilities, pressure regulating stations, pressure limiting stations, pressure relief stations, and fabricated assemblies. Included within this definition are gas transmission and gathering lines, which transport gas from production facilities to onshore locations and gas storage equipment of the closed pipe type, that is fabricated or forged from pipe or fabricated from pipe and fittings.

805.2.4

"pig trap or scraper trap: an ancillary item of pipeline equipment, such as a launcher or receiver, with associated pipework and valves, for introducing a pig into a pipe-line or removing a pig from a pipeline."

Quick-opening closures do not require design or stamp to ASME BPV VIII
831.3.7 Closures

"It is not the intent of this Code to impose the requirements of a specific design method on the designer or manufacturer of a quick opening closure."

Now reread against ss 805.2.4.

Interpretation made by ASME in 1991

Interpretation: 8-3
Subject: Design of Scraper Traps
Date Issued: April 9, 1991
File: B31-90-039
Question(1): Can a barrel of a scrapper trap be designed in accordance with ASME B31.8?
Reply (1): Yes.
Question(2): Can Appendix 24, ASME Section VIII, Division 1 be applied to the design for the end closure, when the clamp type connection is applied to the end closure of the scraper trap?
Reply (2): Yes.

There are B31.8 requirements for quick-opening closures. These are the only ones specifically required by B31.8,

1) Quick opening closures shall have pressure and temperature ratings equal to or in excess of the design requirements of the piping system to which they are
attached.
2) Quick opening closures shall be equipped with safety locking devices in compliance with Section VIII, Division I, UG-35.2 of the BPV Code.
3) Weld end preparation shall be in accordance with Mandatory Appendix I, Fig. I-4.

Safety locking devices in requirement 2 are the mechanical interlocking type that will physically not allow a quick-opening closure to be opened if there is still pressure contained within.

But, as long as you don't violate B31.8 provisions in the process, there is nothing to stop someone from adding features to their design, except the amount of money they have. Such as,

There is no code requirement for 2 valves to be installed in the connection between mainline and trap, or in vents from trap to atmosphere, drains, etc. as some companies also require. But if you want it, write the cheque and you get it.



I hate Windowz 8!!!!

 

[carlo1023]

Thanks guys for your helpful replies.

 

[LittleInch]

My learned poster BI gives a excellent response. I would note in addition that other international pipeline design codes require the end closure to be "designed" to ASME VIII or a similar pressure vessel code, but don't need it to be stamped.

The pipeline codes allow and in practice it normally follows that the pig trap is designed to the pipeline code and not the PV code or the piping code. A pig trap is just a bit of pipe, not a pressure vessel and if you design to a PV or piping code, you often get much smaller ID than the connecting pipeline and also end up with onerous inspection requirements.

So as BI says, once you understand that the end closure doesn't need a U stamp, this answers all your other questions.

One more thing - choose your end closure yourself and don't let the supplier choose the cheapest one he can get - there are some good designs and some bad designs, but you should be deciding which one suits your needs best.

My motto: Learn something new every day

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

 

[BigInch]

I think where money would be very well spent would be to include a pressure gauge.

I hate Windowz 8!!!!

 

[BigInch]

Or Liquids B31.4 § 195.124 Closures.
Each closure to be installed in a pipeline system must comply with the ASME Boiler and Pressure Vessel Code, section VIII, Pressure Vessels, Division 1, and must have pressure and temperature ratings at least equal to those of the pipe to which the closure is attached.


I hate Windowz 8!!!!