How should the design service life be determined?
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This post was last edited by WiseMind on 2024-8-14 at 17:00. Reposted from the WeChat official account “Boiler and Pressure Vessel Design”. Principles for determining the design service life 1. The design service life is determined by the design unit based on the expected service life of the container. The expected service life of the container is specified in writing by the client who commissioned the design to the design firm. The design service life of pressure vessels shall be specified in the design drawings. 2. The design service life of pressure vessels is not equivalent to their actual service life. Users of pressure vessels shall conduct periodic inspections and classification of the vessels in accordance with the requirements of the current regulation, “Safety Technical Inspection Regulations for Stationary Pressure Vessels” TSG21-2016. When the operating conditions of the vessel change, the corrosion rate should be re-estimated based on actual measurement data to determine the vessel’s new service life.
3. The following factors should be considered when determining the design service life of a vessel: (1) selection of appropriate materials and structural design; (2) a reasonable corrosion allowance; (3) suitable manufacturing and inspection requirements; (4) limitation of the possibility of creep (under high-temperature conditions) or fatigue; (5) the cost of constructing the vessel; (6) the role of the vessel within the installation; (7) the operating cycle of the installation. 4. The design service life of vessels should comply with the following provisions: (1) For thick-walled hydrogenation reactors made of chrome-molybdenum steel or high-alloy steel with a nominal thickness ≥ 50 mm: not less than 30 years; (2) For other reactors, towers with a diameter ≥ 4 m, weight ≥ 100 t, or total height ≥ 60 m, shells of high-pressure heat exchangers, vessels with a nominal thickness ≥ 50 mm, and spherical storage tanks: not less than 20 years; (3) For other towers, vessels, heat exchanger shells, and tube boxes: not less than 15 years. 5. For vessels with periodic variations in operating temperature or pressure, the number of cycles of such temperature or pressure changes during the design service life shall be indicated in the design drawings.
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