Issues regarding the filling of the welding joint coefficient in the technical specifications table on the pressure vessel layout diagram, as well as those related to the calculation documents and the inspection ratio
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Issues regarding the filling of the welding joint coefficient in the technical specifications table on the pressure vessel layout diagram, as well as those related to the calculation documents and the inspection ratio. 1. The cylinder body is rolled from steel plates. (1) If the medium, as well as pressure and temperature conditions, require a welding joint coefficient of 1, then this value of 1.0 should be indicated in the technical specifications table on the pressure vessel’s layout diagram. Similarly, when preparing the calculation documents, the longitudinal/circumferential welding joint coefficients should also be set at 1.0; consequently, the RT inspection ratio should be 100%. (2) If the coefficient for welded joints can be set to 0.85 due to the properties of the medium as well as the pressure and temperature requirements, then this value of 0.85 should be indicated in the technical specifications table on the general layout of the pressure vessel. When preparing the calculation documents, the coefficient for longitudinal/circumferential welded joints should also be 0.85; in that case, the RT inspection ratio should be ≥20%. 2. The cylinder is made of steel pipes. (1) If, based on the requirements regarding the medium as well as pressure and temperature, the welding joint coefficient is set to 1, then this value of 1.0 should be indicated in the technical specifications table on the pressure vessel’s layout diagram. Similarly, when preparing the calculation documents, the longitudinal/circumferential welding joint coefficients should also be set to 1.0; in that case, the RT inspection ratio should be 100%. (2) If, due to the properties of the medium as well as the pressure and temperature requirements, a welding joint coefficient of 0.85 can be used, then this value should be indicated in the technical specifications table on the pressure vessel’s layout diagram, with it being specified as a Class B welding joint coefficient. Since cylinders made of steel pipes do not have Class A welds, the longitudinal welding joint coefficient should be set at 1.0, while the circumferential welding joint coefficient should be 0.85. Therefore, for Class B welding joints (which lack Class A welds), the RT inspection ratio should be ≥20%. The above is my understanding regarding the filling of the welding joint coefficient in the technical specifications table on the pressure vessel layout, as well as the issues related to the calculation documents and the inspection ratio; I welcome any corrections from everyone.
1. The overall aspects are fine; this is an old issue. Different factories or companies use slightly different forms and procedures, which also leads to disputes regarding design, verification, and even between the relevant units and boiler inspection agencies. 2. Details need to be specified in more precision; generally, the general drawings indicate the coefficient for vertical weld joints. 3. The steel pipe is used as the cylinder body, and the welding joint coefficient for the circumferential joints depends on the type of joint – whether it involves double-sided welding or single-sided welding with gussets. It’s not as you think; if 1 is not chosen, it becomes 0.85. The value should be determined based on the type of connection and the testing ratio.