3 replies to this topic

[Yajnavalkya]

Dear Members

 

Please help me out with the value of Test Pressure for Vacuum Lines. I couldn't find any direct reference for Vacuum Testing in ASME B 31.3 2010.

 

Regards

[Zauberberg]

This is very interesting subject. I could not find the correct reference myself in any of the ASME standards.

 

In one company where I used to work earlier, for process vacuum piping we actually applied strength test at 100 kPag. The concept behind is that the same differential pressure is applied across the pipe wall, just in reversed direction. Although some industry experience shows that piping joints will leak more under vacuum than under positive pressure.

 

The only relevant code for vacuum piping I found in published NASA files (see attached). Perhaps the best way forward is to get in touch with piping manufacturer - it doesn't cost you anything.

 

 

 

Attached Files

•  UFGS 40 18 00.00 40 VACUUM SYSTEMS PROCESS PIPING (2014).pdf   95.46KB   59 downloads

[fallah]

Yajnavalkya,

 

Vacuum inside a line is a sort of "External Pressure"; then you can apply following fact from ASME B31.3 for your case:

 

304.1.3 Straight Pipe Under External Pressure

 

"To determine wall thickness and stiffening requirements for straight pipe under external pressure, the procedure outlined in the BPV Code, Section VIII, Division 1, UG-28 through UG-30 shall be followed,...."

[Yajnavalkya]

Mr. Fallah

 

The piping I am talking about is only under vacuum sir, so I thought I might find something more of a a direct reference.

 

I also found this to be somewhat similar to my question:

 

B31 CASE 185

Use of Standard Helium Leak Test for a Vacuum-Only Piping System (Para. 345), Page C-11 of ASME B 31.3 2010.

 

But this isn't a straight forward statement like the min 1.1 times design pressure for pneumatic testing.

 

However, I am Still stuck.