Inspection of B31.3 or B31.1 Brazed Pipe Joints

[tc7]

I hope this is the correct forum for my question: We are planning a high pressure air distribution system (line operating pressure to be 2000-2500 psi). For my applcation, I am comparing the requirements of B31.1 and B31.3; Both seem similar insofar as design stress, fabrication and inspection. We plan to use copper nickel pipe with sil-brazed socket fittings (max line size will be 1 1/2" pipe). Valves and equipment terminations will use face seal type fittings. I cannot determine if either B31.1 or B31.3 excludes this type of fabrication.

Also, aside from welder/brazer qualifications, it is not clear to me what level of inspection can be perfomed on this type of pipe joint; aside from final visual and pressure test, what else is appropriate ?? To what extent must an inspector observe in-process joint fabrications, if any??

Thankyou for advice,
Tom

 

[jte]

tc7-

You'll get some responses here, but a better forum to place your question on would be the Piping and Fluid Mechanics Engineering forum.

http://www.eng-tips.com/threadminder.cfm?pid=378

jt

 

[metengr]

The in-process involvement of the Inspector will probably be based on the owner's contract requirements. We have installed similar high pressure air lines at our Plants and used B31.1 as a guide. We had no Jurisdiction regulations that required us to mandate B31.1 and associated paperwork.

The Inspector, as a minimum, would probably review brazing procedure specifications, and brazer qualification records by the contractor. For field brazing, the in-process involvement could be a review of joint cleanliness, fit-up and watching field brazing. After watching several brazers in action, you can get a quick feel for how the job will go. The success with brazing is joint preparation, CLEANLINESS and the application of flux.

As far as field inspection of brazed joints, a visual and pressure test are more than adequate for this application. I have tried to use spot ultrasonic examination test methods on larger diameter pipe joints to check for bond integrity. The spot UT was not very practical, and provided mixed results.

 

[bvi]

5% in-process examination would be required by ASME B31.3. This is essentially what is described by metengr. it would be done by the examiner, under the oversight of the owner's inspector.

 

[GenB]

Process piping inspection depends on the Jurisdiction and its requirements.In California DOSH, a div of CAL-OSHA has jurisdiction and will inspect process piping.
it is the contractor's and owner's re responsibility to call them and arrange for inspection. or they may just disregard your call who knows,
they are more on boilers and pressure vessels, but as I said its the Jurisdiction.
ER