Are 100% RT inspections required for Class AB welds of pressure vessel shells containing hydrogen?

Regarding whether 100% radiographic testing (RT) is required for the welds of pressure vessels containing hydrogen in the medium, this must be determined based on specific **or regional regulations as well as the requirements of the project. Under normal circumstances, weld joints can be classified into various categories based on their importance, such as Classes A, B, C, and D welds as specified in ASME VIII (Volume VIII of the American Society of Mechanical Engineers). Among them, Class A welds generally refer to the welds in the main pressure-bearing components that are subject to the greatest stresses, while Class B welds are those in the non-primary pressure-bearing components. Class A welds generally require a higher level of non-destructive testing coverage, whereas the requirements for Class B welds may be relatively less stringent. As a medium, hydrogen poses higher requirements for the weld quality of pressure vessels due to its high permeability and the risk it poses of causing metal embrittlement. Some standards or specifications may require 100% radiographic testing of all welds in pressure vessels operating with hydrogen media, or of specific types of welds, in order to ensure the reliability of those welds and the safety of the entire pressure vessel. For example, if a project complies with the ASME Pressure Vessel Code, one can refer to UG-116 in ASME Section VIII, Division 1 for the inspection requirements regarding welding, or related articles such as UC-77 and UC-250, to determine the radiographic inspection requirements for specific weld categories. Regarding your specific question, whether 100% radiographic testing is required for Class AB welds of pressure vessel shells containing hydrogen depends on the following factors: 1. The applicable design and manufacturing codes or standards for pressure vessels (such as ASME, GB 150, etc.). 2. The pressure exerted on the container, the temperature, and the severity of the operating conditions. 3. Safety requirements of the using unit and engineering design requirements. 4. Regulations or industry requirements may impose additional safety testing requirements for specific media. Therefore, you need to consult the relevant standards for the design and manufacture of pressure vessels, safety regulations, as well as the project requirements, in order to determine whether 100% radiographic inspection is necessary for Class AB welds. If necessary, it is recommended to consult a professional pressure vessel design and inspection agency directly. .

The design pressure is 2.5 MpaG; the design is carried out in accordance with national standards 150 and TSG21.

Design pressure: 2.5 MpaG; design temperature: 70. It is a Class III pressure vessel, designed in accordance with national standards 150 and TSG21.

Class AB welds of Category 3 pressure vessels with a design pressure of 1.6 MPa or higher shall be subject to 100% radiographic or ultrasonic testing

Can reinforcing rings be used for the large openings in this type of equipment?

This post was last edited by wanlirn on 2023-12-18 at 15:56. It’s not allowed – reinforcement rings are prohibited in most engineering applications, especially for Category 3 critical equipment. Our company has been prohibiting the use of reinforcement rings even when containers are used, and this policy has been in place for over a decade. The new version of GB150 imposes strict restrictions on the use of reinforcement rings, which indicates that their use is also not recommended, with a trend toward banning them.

Hydrogen is not a highly hazardous medium; whether Class AB requires 100% RT depends on the design parameters, as well as the material and thickness used in the calculations. You can refer to 3.2.10.2.2.2 of the Fixed Volume Code and 10.3.1 of GB/T150.4