Conditions for exempting containers from fatigue service
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I have a question for everyone: In clause 3.10.2.1 of standard JB/T4732, for steels with a tensile strength of not more than 550 MPa, the total number of cycles specified is not more than 1000 times; a) this includes the number of cycles for full-range pressure cycles, including start-up and shutdown. b) The number of cycles during which the pressure fluctuation exceeds 20% of the design pressure. Cycles in which the pressure fluctuation does not exceed 20% of the design pressure are not counted. If the pressure fluctuation of a device is 0–1.0 MPa, its maximum operating pressure is 1.0 MPa. So, by increasing the design pressure to 5.1 MPa, can fatigue design be eliminated? Since the equipment has a small diameter and is made of carbon steel, the cost increase upon increasing pressure is limited. Additionally, how should the “full-range pressure cycle” in the standard be understood? Can this device be understood as operating in a 0-5.1 MPa cycle?
Raising the design pressure to 5.0 MPa eliminates the need for fatigue analysis; the full range of pressure cycles for this equipment is 0–1.0 MPa, which is independent of the design pressure
The main body is fine, but are the other components viable? ?
If it is as you say, with the full pressure cycle being 0–1.0 MPa, then this equipment may not be exempt from such requirements, because there are 80 cycles per year and a design service life of 20 years, resulting in more than 1,000 full pressure cycles in total.