Leak Testing

[NewMechanicalEngr]

Hi all,

Process conditions:

1. Compressor Engine Exhaust
Press: 1-2 psig
Temp: 1500 F (max) w/ a 1250 F shutdown
Material: 316 SS
Spec: Class 150

a. We are shop fabricating new sections of 316SS piping (approx 10' long) that will have multiple nozzles. I planned on specifying hydrotesting with potable water.
Q1. Is this reasonable?
Q2. How do I determine the test press and temp?

b. There will be a field cut and field weld of a 14" flange on one of these sections. Considering the spool will have been hydrotested already, can the field weld be dye pen tested to prove its worthiness?

Thanks

 

[BigInch]

What's the code?

I'd be surprized if any code applies to 2 psig exhaust piping, so welding, hydro and finished joint testing is more likely to be only required if specified by a particular contract spec or requirement.

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[0707]

Q1 as it is a SS 316 your test water must have less than 50 ppm of chlorides.

Q2 as a rule normaly test pressure is 1.5 times design pressure, test temperatures are done normaly at 15 ºC.

b)A dye penetrant doesn´t replace a hydrostatic test,

If is umpraticable to hydrotest the 14" flange you should complement the dye penetrant with 100% Rx.

 

[metengr]

a. We are shop fabricating new sections of 316SS piping (approx 10' long) that will have multiple nozzles. I planned on specifying hydrotesting with potable water.
Q1. Is this reasonable?

Hydrotesting in this application will only serve to look for defective material and welds. Is this reasonable? No, because NDT could be used in lieu of hydrotesting to evaluate weld quality. If you hydrotest, you need to make sure that the chloride level is controlled to a maximum level (say 500 ppm).

Q2. How do I determine the test press and temp?

Unless required by contract, the hydrotest pressure can be 1.3 to 1.5X maximum working pressure. The temperature is typically ambient conditions.

b. There will be a field cut and field weld of a 14" flange on one of these sections. Considering the spool will have been hydrotested already, can the field weld be dye pen tested to prove its worthiness?

Yes, it can.

 

[BigInch]

So at 2 psig working pressure he can stand the pipe up on end and fill it with water to get over 2 X design pressure on the end, turn it upside down, do it again ....... oh oh, still leaves the middle.

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com