B31.3 5% Radiography Conformance Requirement

[magusinp]

Our company manufactures Magnetic Level Gauges to order. We are registering this product line with CSA (CRN number) as being built under ASME B31.3 We are seeking to conform to the Examination Requirements of Ch. VI of Asme B31.3 before I get the ASME Inspector out here to certify our QC conformance. In paragraph 341.4.1(b)(1) the code requires "Not less than 5% of circumferential butt...welds shall be examined fully by random radiography" Later, in the same paragraph, it also states "In-process examination in accordance with para. 344.7...may be substituted for...radiographic...examination.." (Please see code for all the details I left out with my use of elipses; or you can read the extracts in the attachment) On our gauge each housing has one girth weld, two full penetration branch welds and 4 fillet welds. How is the 5% requirement usually handled? As you can see, it is difficult to figure out what 5% means in a made-to-order OEM case; but I am sure that there is a precedent that is accepted. All our welders and WPS are registered and tested. Is the "In-Process examination" normally accepted?

 

[eliebl]

The 5% is the percentage of welds to be radiographed on a lot basis. In a made to order job this is likely going to be 5% of each assembly. There is also another important item to keep in mind. Each welder must be sampled. If two different welders weld on one component (lets say 2 seams each) then you must radiograph two of the four seams. That results in an actual radiography 50% when only 5 % is required. The inportant words in relation to the in-process examination are "if specified in the engineering design". If the CRN was registered permitting in-process examination then the regulatory body would likely have asked some specific questions. In the case of in-process examnation they (I have worked for one jurisdiction) would have asked for details of the in-process examination.


In-process ezxamination is usually reserved for closure welds (in B31.3 parlance) or "Golden Welds". You can search these forums for the length discusion and differing opinions on closure welds.

EJL