Discussion on UT inspection grades for plates and hardness testing after heat treatment
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This post was last edited by gn_1984 on 2020-4-15 at 12:55. Recent issue 1: For a certain analysis and design device, the design pressure is 4.0 MPa, the operating pressure is 0.8–1.2 MPa, and the design temperature is 250°C. The medium is wet natural gas (sulfur-free), and the material used is Q345R with a thickness of 24 mm; these specifications meet the requirements outlined in JB4732-95. 100% UT testing is carried out on the steel plates, and the results meet the standards specified in JB/T4713.3, at least at grade III. Some people believe that due to the introduction of the new non-destructive testing standard NB/T47013-2015, as well as the amendments to NB/T47013.3 in 2018, the requirement in JB4732-95 for a grade of not lower than III is equivalent to the requirement under the new non-destructive testing standard and the amendments NB/T47013.3, which calls for a grade of not lower than II. They suggest that the requirement for testing the plates of this equipment should be a grade of I, which would correspond to the II grade requirement specified in JB4732-95. There is also such a divine correspondence: L. Have my colleagues encountered this problem before? How exactly do people understand and implement it? Question 2: Still regarding the equipment from Question 1, overall heat treatment is required after welding. Is it necessary to specify requirements for testing the hardness of the welds? What is the basis for this? Is it still necessary to conduct hardness testing on all Q345R equipment that has been analyzed and designed, after heat treatment? Please share your opinions and discuss learning together.
Colleagues and seniors, please give me your guidance. Feel free to share your valuable opinions:lol
Firstly, I think that for Q345R plates with a thickness of 24mm, they meet the first-grade requirements in terms of factory UT testing. Apart from writing papers, in practical applications it doesn’t really matter what grade they achieve. Secondly, we have dealt with many containers that require analysis and design; for Cr-Mo steel after heat treatment, it’s standard practice to measure its hardness. I haven’t seen any specific requirements regarding hardness testing for Q345R plates
This post was last edited by ldx2008 on 2020-4-15 at 17:26. Among the design drawings produced by major design institutes that I’ve seen recently, there are devices that require overall heat treatment after welding; for materials such as Q245R or Q345R, requirements for hardness testing of the welds are also specified. It might be in accordance with the requirements of clause 7.8.2 of HG/T20581-2011, or the requirements of GB/T 27866-2011 \"Technical specifications for controlling the hardness of welds in steel pipes and equipment to prevent sulfide stress cracking\"
A new standard has been introduced, and there is no problem in implementing it. As for the necessity of testing the hardness of materials such as carbon steel and Q345R after stress relief treatment following welding, it’s also unclear; one should study this further.
In Amendment 1 to NB/T47013.3-2015, only the ultrasonic grade code for steel plates was changed; it seems that the acceptance criteria remain unchanged. Why was this change made? Is it to integrate with the international community?
My understanding is that the requirements of Design Specification 4732 specify compliance with the corresponding grades of the non-destructive testing standards; non-destructive testing should be carried out in strict accordance with the grades specified in the design specifications. Any changes to the non-destructive testing standards are not directly related to 4732 – they merely result in higher requirements for the implementation of those standards. According to this interpretation, since there are amendment documents for the non-destructive testing standards that raise the requirements compared to those previously in place, the requirements specified in the design codes should also be increased accordingly to match these amendments to the non-destructive testing standards. This is the first time I’ve heard of such a claim, so I’d like to hear from my colleagues: when carrying out ultrasonic testing on panels during design, does the standard used correspond to a level that is higher than what’s specified in the design guidelines?
This device is not in a stress-corrosion environment; even if it were, the requirements for hardness testing and material specifications would be higher
I am extremely grateful for the insightful comments from my senior. I agree with your view.
The designer raising the quality standards themselves is a form of self-protection. However, this also led to increased production costs.
Original poster, I took a look at the standards for 4732. Clause 6.2.5 on page 25 of those standards specifies that the ultrasonic testing and quality requirements for steel plates shall comply with GB/T2970 (note: JB/T2970 in that document is a printing error; the correct standard to follow is GB/T2970). After checking online, the latest version of standard 2970 is from 2016, and it has not been repealed. In my opinion, the UT testing of steel plates in accordance with standard 4732 has no relation whatsoever to JB/T47013 or NB/T47013.3 and their amendment sheets, let alone any kind of correspondence between them. Executing it according to Clause C poses no issues.