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Sonotron NDT
Original developer and manufacturer of advanced ultrasonic instruments

863 views
11:15 Feb-12-2010

Antonio Sousa

NDT Inspector
ALSTOM PORTUGAL,
Portugal,
Joined Nov 2003
4
RT - Number exposures

I need to know if are correct when make a RT Procedure according ASME V, put the table A4 from EN 1435 for determining the quantity of exposures at the piping.

 
21:11 Feb-16-2010
Slawomir Mackiewicz
Re: RT - Number exposures In Reply to Antonio Sousa at 11:15 Feb-12-2010 (Opening).

Dear Antonio

Mixing of requirements of different standards is not a good practice from formal as well as from technical point of view. Each standard requirement is a part of a complex system of interrelated requirements and rules which form the standard. You shouldn’t take them individually without considering the whole.

In your case, if you draw RT procedure according to ASME V you should follow its rules in all respects, also in determining the number of exposures for circumferential welds. So, instead of referring to Fig. A.4 in EN 1435 you should use the clause T-271.2 of ASME V, Article 2. For example, for typical double-wall exposure, single-wall viewing technique (Exposure arrangement D), it requires a minimum 3 exposures taken 120 deg to each other.

Of course this is only a MINIMUM and you have to remember about all other rules of ASME Code. Specifically, in this case, you have to check if your RT technique ensures radiograph density limitations according to clause T-282.1. In some cases of heavy wall piping you may not be able to meet this requirement with only 3 exposures. You may find some help on the subject on my web site: http:\\www.ndtsoft.eu

Best Regards

Slawomir Mackiewicz

 


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