The issue of allowable stress in copper pipes
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Table 5-4 of JB/T 4755-2006 \"Copper Pressure Vessels\" specifies that the allowable stress for GB11791 copper tubes is 30 MPa at 20°C and 25 MPa at 100°C. Table 2 of GB/T18033-2017 \"Seamless copper water pipes and copper gas pipes\" specifies that at an operating temperature of 65°C, the corresponding values for different hardness levels are 63 MPa, 50 MPa, and 41.2 MPa. Why is there such a large difference between the allowable stresses specified in these two standards? How should one make a choice in the calculation of pipe wall thickness?
In my understanding, the scope of application for these two standards is different, just like 13296 and 14976 in the case of pressure vessels