What determines the design service life of pressure vessels?

There is a recommended usage period! After reaching the design life, an application can be submitted for re-inspection; if it passes, it can continue to be used.

The \"Regulations on Safety Technical Inspection of Fixed Pressure Vessels\" stipulate that the design service life of the pressure vessel shall be indicated on its design diagram (and the number of cycles for fatigue-resistant vessels). Under normal circumstances, the specific expected actual service life should be specified in writing by the client who commissioned the design (the user) to the design firm, which then determines the corrosion margin based on that service life and the rate at which the medium corrodes the equipment. Design life: Corrosion margin = Annual corrosion rate × Design life span. When determining the design life of pressure vessels, the following factors should generally be taken into consideration: ★The mechanical properties of the material, such as the dependence of high-temperature creep and high-temperature fracture on time ； ★Design life factor included in the corrosion margin ； ★The temporality of loads such as periodic loads ； ★Abnormal factors such as improper operation or harsh environments: According to HG/T20580-2011 \"Basic Provisions for the Design of Steel Chemical Vessels\", for ordinary vessels and heat exchangers: 10 years ； Fractionating towers, reactors, high-pressure heat exchangers: 20 years ； Spherical vessel: 25 years ； Important reaction vessels (such as thick-walled hydrogenation reactors, ammonia synthesis towers, etc.): 30 years.

There are regulations stating that whether a time limit is applied depends on the design firm; it’s not specified that use will be denied if the limit is exceeded, but the cost will be very high, which is quite troublesome