Regarding the issue of how many grades of qualification are required for main steam pipe welds
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We are waste heat boilers for gas-steam combined cycles, with main steam parameters of 3.82 MPa/450°C. The welding design specified by the design institute for the main steam pipes is actually: spot checks of 10%! ! ! The weld quality grade is qualified at level III! ! Damn it, what an amateurish design firm! For the first question, I found it in Table 5 of DL/T 869-2012; 50% should be sampled. As the owners, we demand the highest standard and insist on raising it to 100%. Second question: Are there any specifications that specify what the acceptable quality grade is for welds in steam pipes under certain pressure and temperature conditions? Is it Grade I, Grade II, Grade III, or Grade IV? It seems there are no regulations on this in NB/T 47013, nor in DL/T 869. . . DL/T 869 only provides a brief description of levels I, II, and III; there is no relevant information indicating what quality level is considered acceptable for welds in steam pipes operating under certain pressure and temperature conditions Also, is RT generally used for the non-destructive testing of pipe butt welds? Later, we used sub-critical parameters, aiming for the higher end rather than the lower, to ensure at least a Level II qualification. . . However, no relevant specifications were found. Dear sea friends, is there anyone who is familiar with this area? I would appreciate your guidance.
All of your design requirements can be met 100%. . . . They made the changes as you requested
All of your design requirements can be met 100%. . . . They make the changes as you request, and you pay them proportionally. .
This post was last edited by nj1952 on 2017-7-14 at 10:46. Table 5 of DL/T 869-2012, \"Code for Welding Techniques in Thermal Power Plants,\" specifies the scope, methods, and proportions for the classified inspection of weld joints. (2) Based on the operating conditions you provided, the category of the pipe butt joint is Class I. (3) Under these operating conditions, and considering the type of welded joint, the proportion of non-destructive testing (radiographic or ultrasonic) specified in DL/T 869-2012 is 50%. (4) DL/T 869-2012 specifies that the quality level for non-destructive testing of Class I welded joints is: radiographic testing at Level II ； Ultrasound examination: grade I. (5) For the selection of radiation testing (RT) or ultrasonic testing (UT), please refer to Article 6.3 of DL/T 869-2012.
The GB50235 Code for Construction and Acceptance of Industrial Metal Piping mentions the quality grades of welds
This post was last edited by waaabc on 2017-7-14 at 13:47. I don’t think the design institute made a mistake in its choice; first, you need to confirm that your organization is in the power sector before considering the use of standard DL/T 869-2012. It is recommended that the original poster check GB20801-2006; for industrial pipelines, the acceptance rates for non-destructive testing are 100%, 20%, 10%, and 5%. Grade II compliance applies to a 100% testing rate, while the other rates correspond to Grade III compliance. This steam pipe can only be considered GC2 grade; using 10% non-destructive testing still meets the specifications. Of course, the owner also has the right to set higher requirements, after all, it is they who are paying for it:D
Yes, we are a gas power plant. So, enforce electrical standards.
Is the category of the pipe butt joint Class I? Which specification defines it explicitly? Let me take a look. Thank you so much for your patient answers; I am extremely grateful!
It mentions the weld quality grade, but does not specify which grade should be used for the welds of pipes operating under conditions of certain pressure and temperature levels.
Please study carefully * DL/T 869-2012 \"Code for Welding Techniques in Thermal Power Plants\". Also, I agree with the view from the 6th floor; that’s what I wanted to say as well.
The power industry has acceptance standards for welding work; you can take a look at them