When performing design calculations for pressure vessels, is it safer to use a smaller welding joint coefficient?

The weld joint coefficient refers to the ratio of the actual strength of a weld joint to its theoretical strength. In the design calculations for pressure vessels, the smaller the welding joint coefficient, the greater the actual strength of the welding joint, and thus the higher the safety level of the vessel. Therefore, generally speaking, the smaller the welding joint coefficient, the safer it is. Of course, the weld joint coefficient cannot be made arbitrarily small. Since a too small welding joint coefficient can also affect the safety of the container, it is necessary to select an appropriate coefficient based on the specific circumstances. In practical applications, a welding joint factor of 0.85 is quite commonly used, and this factor already provides sufficient safety assurance. However, if the operating conditions of the container are quite harsh under certain special circumstances, it is recommended to make adjustments based on the actual situation. .

The weld joint factor cannot directly indicate whether a container is safe or not. Because the proportion of non-destructive testing and the acceptance criteria for a welding joint coefficient of 0.85 are lower than those for a welding joint coefficient of 1.0 ； The welding joint coefficient is also related to the type of weld. It can only be said that no matter what value is assigned to the welding joint coefficient, as long as the design and manufacturing are carried out in accordance with standard specifications, the safety risk remains acceptable.

Just follow the standards; the allowable stress itself already takes into account a safety factor and provides sufficient margin. On the other hand, there are testing methods and pressure tests available for verification.

On the contrary, the smaller the coefficient, the lower the requirements for welding and inspection, the poorer the quality, and the less safe it is

Let me rephrase the question: Since the detection rate is 100%, is it safer to use a joint coefficient of 0.85 in the calculations rather than 1.0?

This post was last edited by xlxuiin on 2023-7-4 16:01. The welding joint coefficient should be determined based on the type of weld and the proportion of the length subject to non-destructive testing.