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Pipe weldment question

Pipe weldment question

Pipe weldment question

Newbie here-

A large machine we build and sell has an air compressor that feeds an air holding tank. The compressor is either diesel or electric motor driven. The air holding tank is an ASME "U" stamped pressure vessel, MAWP is 250 psi.

There is a short pipe that connects the air compressor to the ASME air tank. The pipe is basically a 90 deg. elbow with a butt welded flange on each end. (8" nom. dia.) This pipe spool piece connects the compressor and the ASME pressure vessel. This pipe piece is a subcontracted purchased item, and I recently noticed visually some weld quality issues on the flange welds.

My question is: Is the manufacturer (vendor) of this welded pipe piece required to have some qualification, or certificate of authorization, ...like a "PP" stamp?

RE: Pipe weldment question

If the pipe piece was specified as complying with ASME B31.3 Piping Code, it should have been inspected in accordance with that Code.  There is no Code stamp for B31.3 piping, but you have to fall back on specs and documentation of materials, fabrication, weld procedures, welding qualifications, and shop inspection.  Your pressure of 250 psi obviously requires compliance with B31.3 Code (in the USA).


RE: Pipe weldment question

TangoCleveland, what legal authority in the USA requires compliance with B31.3 for a 250 psi air compressor pipe.

RE: Pipe weldment question

Zapster - good point.  I found no Federal requirement for Code compliance on Piping or Pressure Vessels.  I am used to designing piping and pressure vessels to Code, but why do we do it aside from Company Specs & Requirements?  I suspect it's a State or Local jurisdictional issue.  

I work at NASA in Cleveland; NASA is applying Code compliance requirements internally.  In addition, State of Ohio requires Code compliance --

Ohio Revised Code:
§ 4104.42. Duties of owner of power piping or process piping system.
(A)  The owner of any power piping or process piping system shall ensure that all of the following are performed in compliance with applicable sections of the B31 standards contained in the code for pressure piping, published by the American society of mechanical engineers:
(1) The design, fabrication, assembly, installation, testing, examination, and inspection of power and process piping systems;
(2) Qualification of personnel and qualification of welding and brazing procedures;
(3) The implementation of an inspection program.

Also addresses records and documentation.  Compressed Air piping is included in the scope.


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