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Pressure pipeline Design units should obtain the corresponding level of pressure pipeline design qualification certificate.
1. Upper limit of material usage temperature
1) The use temperature of the material should not exceed the current national standard "Pressure Pipeline Specification Power Pipeline" GB/T 32270-2015 Appendix A gives the maximum temperature of the allowable stress value;
2) Determining the upper limit of the actual use temperature of the material, the influence of corrosive media should be taken into account. Materials used for a long time under high temperature conditions should consider the impact of changes in tissue or performance on the reliability of the material use. Materials used for a long time above the creep temperature should consider excessive deformation, excessive displacement, deterioration of material structure and performance, and stress relaxation of bolts due to creep;
3) carbon steel . Carbon manganese steel should not be used for a long time at temperatures above 425℃, and carbon molybdenum steel should not be used for a long time at temperatures above 470℃. However, in the direct air-to-air emission pipeline of self-limited pressure relief safety device, carbon steel can be used for 425℃ or above
4) When chromium molybdenum alloy steel is used for a long time at a temperature of 400-550℃, appropriate protective measures should be taken based on the use experience and specific working conditions. ) When using low alloy chromium steel (2.25% chromium) at temperatures above 454℃, the carbon content of the base material and weld filler metal should be equal to or greater than 0.05%
6) ferritic stainless steel and martensitic stainless steel should not be used at temperatures above 370℃
7) chromium nickel austenitic stainless steel should be used for long-term use at temperatures of 540~900℃ ml5 austenitic steel content and excessive cold deformation in ml5 austenitic steel ;
8) duplex stainless steel must not be used at temperatures above 300℃
9) When the use temperature of austenitic steel is higher than 525℃, the carbon content in the steel should not be less than 0.04%;
10) The restrictions on the use of materials in GC-type pipelines at high temperatures should comply with the national standard "Pressure Pipe Specifications" Regulations of Industrial Pipeline Part 2 Materials" GB/T20801.2.
2. Lower limit of material usage temperature
1) Designers should consider the possibility of brittle fracture in at low temperatures;
2) The lower limit of material usage temperature of GC pipes should comply with the national standard "Pressure Pipeline Specifications Industrial Pipe Part 2 Materials" GB/T20801.2
