Help: Issue with service life
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For a pressure vessel, is it possible to determine its remaining service life based on the operating medium conditions, by comparing the originally designed wall thickness with the actual wall thickness, and by taking into account the corrosion margin as well as strength or stiffness? How should this be calculated, and are there any standard documents that can be referred to? Thank you. .
Regarding the remaining service life of pressure vessels, it can generally be determined by comparing the original designed wall thickness with the actual wall thickness, as well as by taking into account the corrosion margin and strength or stiffness. However, the specific calculation methods and standard documents require reference to the relevant regulations of the **and the industry. In China, the following standards and specifications can be referred to: 1. GB/T 19624-2004 \"Code for Inspection and Assessment of Metal Pressure Vessels in Service\": This standard provides general methods and procedures for the inspection and assessment of pressure vessels in service. For pressure vessels that are already in use, inspections, tests, and evaluations can be carried out in accordance with the guidelines and methods provided, in order to determine their remaining service life. 2. TSG R0004-2009 \"Regulations on Safety Supervision of Special Equipment – Pressure Vessels\": These technical regulations provide guidelines for the safety supervision of pressure vessels, including requirements regarding their service life and other aspects. Based on these regulations, and taking into account the actual usage conditions of pressure vessels, the remaining service life of such vessels can be determined using relevant calculation formulas and methods. 3. JB/T 4730-2005 \"Code for Assessment and Evaluation of Non-Destructive Testing of Metal Pressure Vessels (Equipment)\": This standard specifies the methods for assessing and evaluating non-destructive testing of metal pressure vessels, including assessments of aspects such as vessel wall thickness, corrosion margin, and load capacity. By performing non-destructive testing on pressure vessels, relevant data can be obtained and evaluated to determine the remaining service life of the vessels. It should be noted that in practice, the assessment of the remaining service life of pressure vessels must be carried out in accordance with the regulations and standards of the relevant ** and region, as well as the specific industry requirements. For more specific technical issues, it is recommended to consult a professional pressure vessel inspection agency or technical expert. .
Consider it from two aspects. 1. The service life indicated on the as-built drawings. 2. A certificate of conformity issued by the special inspection agency upon regular inspection. Theoretically, the actual service life can be calculated by using the corrosion margin indicated on the as-built drawings divided by the corrosion rate. However, when the service life exceeds the period indicated in the as-built drawings, the equipment must be retired even if there is still a corrosion margin; if extended service is required, approval from a specialized inspection agency is still necessary.
For containers that are already in use, an erosion rate can be estimated based on existing data; the remaining service life is obtained by dividing the remaining corrosion margin by this erosion rate. Since, in addition to the corrosion margin, there may also be a certain amount of rounding in the design of the container, if this rounding is to be utilized as well, it is necessary to carry out calculations based on the design standards for that container in order to determine the calculated thickness of each component (this calculated thickness must take into account factors such as reinforcement due to openings). The remaining usable corrosion margin is then obtained by subtracting the calculated thickness from the actual measured thickness.