Summary discussion of the two true/false questions from yesterday

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1. In the GB150-1998 standard, the calculation formula for the internal pressure of a cylinder at the design temperature, δ=PDi/2tφ-P, is applicable to the design of steel pressure vessels with a design pressure not exceeding 35 MPa. ( ) 2. During pressure testing, the membrane stress in the cylinder of a pressure vessel shall not exceed 90% of the material’s yield strength σs (σ0.2) at the test temperature. ( ) These two questions were used as exam items, and most people probably got the answers right. However, as for exactly where the error lies, the answers in the replies aren’t complete for everyone. I’ll give a brief summary first, and I hope everyone can provide additional information to arrive at the final answer. 1. 1) P is the design pressure, whereas the formula should be for calculating Pc, the pressure. 2) There is another condition regarding the scope of the formula: Pc≤0.4tφ. 3) As for the minimum pressure being no less than 0.1MPa, this falls outside the scope of GB150. Personally, I don’t think it’s a wrong reason to not do W. 2. 1). For this question, the first reason most people mention is that the pneumatic test should be at 80%. 2) As for the suggestion to multiply by a weld coefficient. I’m not sure about that either. If we add this item to separate air pressure from hydraulic pressure. Is it correct? I would appreciate it if you could share your views further.