Issues regarding non-destructive testing of the surface of stainless steel containers
Thread Content
This post was last edited by zjq1962 on 2019-11-26 at 13:07, as shown in the attached diagram: Both GB/T150.4 and the relevant code specify that for austenitic stainless steels of a certain thickness or more, surface non-destructive testing of their welded joints is required. However, there are two differences in their descriptions: first, the way thickness is expressed differs; GB/T150.4 refers to the thickness of the steel, while the tolerance specification refers to the thickness of the joint. Which of the two expressions is more reasonable? Second, GB/T150.4 includes austenitic-ferritic duplex stainless steels, while the tolerance standards classify duplex steels under Article 4; according to standard 150, only duplex stainless steels with a thickness exceeding 20 mm require non-destructive surface testing. According to the fixed-volume regulations, all duplex steels specified in GB/T24511 (whose minimum standard tensile strength exceeds 540 MPa) must undergo surface inspection, regardless of their thickness. Even when taking into account both i in 10.3.1 and b in 10.4 of GB/T150.4, surface inspection is only performed on duplex steels with a thickness greater than 16 mm.
Yes, there is indeed this problem. The main reasons lie in issues related to time and basis; the year specified in GB150 is 2011, and it is based on the 2009 version of the Code for Fixed Pressure Vessels. Moreover, the latest version of the Code for Fixed Pressure Vessels is the 2016 edition, which is another 5 years behind GB150. It is therefore evident that the requirements of the 2016 version of the Code for Fixed Containers are stricter than the 150 specified in the 2011 version. Perhaps the next version of GB150 will be the same as the 2016 version of the Code for Fixed Pressure Vessels. Now, we can only proceed in accordance with strict requirements.
The requirements in this regard for the old version of the tolerance specifications and the higher tolerance specifications remain unchanged, right?
According to the higher standard GBT150－2011, it is really unreliable in terms of heat treatment and non-destructive testing
The requirements specified in the code are the latest ones. During this continuing education course, experts also said that 100% PT testing is required as an additional inspection method for all welds in duplex steel: lol
The requirements for surface non-destructive testing in the 2009 version of the Code for Solid Materials have been revised. It was not mentioned in the 1st edition of 2009; it was added and modified in the 2nd edition.
The thickness specified in the terms is reasonably based on the thickness of the welded joint.
The principle we follow is that containers subject to acceptance regulations are governed by the fixed capacity regulations, while those not subject to such regulations are governed by GB150
For containers governed by capacity regulations, if national standards require a higher level than the regulations, the higher standard must be followed.
The large capacity specification is the minimum requirement. One is a technical specification and the other is a standard.