Wednesday, May 11, 2011

Re: [MW:11021] Query / NDE Procedure / ASME Sec VIII Div 1

Dear Vino,
A)  As I understand that Radiography Examination is having predominate over UT Examination for all Pressure Vessel as per this division, but as per UW-51 it does not require any written Procedure. Why?
ASME Section VIII Div-1 UW-51 (a) (2) clearly states that 

A written radiographic examination procedure is not required. Demonstration of density and penetrameter image requirements on production or technique radiographs shall be considered satisfactory evidence of compliance with Article 2 of Section V.
The second line gives you a clear reason.
Your other Question:
1. Do we require a UT Procedure to be demostrated for U-Stamp Pressure Vessel? If so, how to prepare a mock up and please provide a reference in ASME for preparation of mock-up.
The UT procedure need not be demonstrated.
2. What is the limitation of Pressure Boundry in Pressure Vessel? Is it the first welding ? Does further nozzle or pipe spool includes in the Pressure Vessel?
The following is the extract from Sec VIII Div 1 on the pressure boundary:
In relation to the geometry of pressure containing parts, the scope of this Division shall include the following:
U-1(e)(1) where external piping; other pressure vessels including heat exchangers; or mechanical devices, such as pumps, mixers, or compressors, are to be connected to the vessel:
(a) the welding end connection for the first circumferential joint for welded connections [see UW-13(h)];
(b) the first threaded joint for screwed connections;
(c) the face of the first flange for bolted, flanged connections;
(d) the first sealing surface for proprietary connections or fittings;

Please note that (a) for welded connections: means the piping is connected to vessel by means of welding, like Boiler blow down vessels, where you will not see flanged connections.
Since your case is not directly connected to piping by welding, but by Flanged connection, the face of the first flange becomes pressure boundary.

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