Reasonable material selection is one of the difficulties and key points in pressure vessel design
The intrinsic factors that determine the safety of pressure vessels are the structure and material properties. Material is the material basis of the equipment, and the material performance has a significant impact on the safety of the pressure vessel. Reasonable selection is one of the basic tasks for the design of pressure vessel, pressure vessel in the life cycle to the safe and reliable operation, designers should not only understand the performance of raw materials, but also to understand the manufacturing process, use of the environment and the effects of time on the properties of materials. There are many factors affecting the properties of materials, and the reasonable selection depends on the qualitative analysis and experience accumulation.
The proportion of the total cost of the pressure vessel material is very large, generally more than 30%. Improper selection will not only increase the cost, but also may lead to pressure vessel damage accident. Multi functional diversity of production process and process equipment, bring a certain complexity to material; with the science of making semi empirical semi scientific (skill) nature brings difficulty to material; material in process equipment design, manufacturing and testing processes in a relatively backward state.
Selection of the following principles
1 the use of the equipment and operating conditions, such as temperature, pressure, medium characteristics and work characteristics, etc.;
2 the mechanical properties of the material, the pressure vessel steel, especially the steel used for pressure bearing components, has a large plastic storage and high toughness;
3 material welding and hot and cold processing performance;
4 equipment structure and manufacturing process;
5 the source of the material, the procurement cycle and economic rationality, such as the choice of the pressure gauge specification recommended materials and domestic materials standards in the existing materials, as far as possible the use of domestic materials;
6 pay attention to the unity of timber in the same engineering design.
A,
Under the above conditions, the following provisions are generally considered to be economic and reasonable:
1 when the thickness of the steel plate is less than 8mm, the carbon steel plate should be used as far as possible between the carbon steel and the low alloy high strength steel.
--HG/T20581 (P52) 5.0.2
2 in the case of stiffness or structural design, the choice of ordinary carbon steel. Based on the strength design of the occasion, should be based on the pressure, temperature, medium use restrictions, using Q235A, Q235B, Q235C respectively, Q245R, Q345R steel, Q235B, Q235C in the selection of pressure components, Q245R and Q345R steel.
--HG/T20581 (P52) 5.0.2
3 when the thickness of stainless steel is more than 12mm, the lining, composite, surfacing and so on should be adopted.
--HG/T20581 (P52) 5.0.2
4 stainless steel should try not to do the design temperature is less than or equal to 500 degrees of heat resistant steel.
--HG/T20581 (P52) 5.0.2
5 Pearlite Heat-resistant steel should try not to do the design temperature is less than or equal to 350 degrees of heat resistant steel. In the case of the use of pearlitic heat-resistant steel for heat or hydrogen resistance, the varieties and specifications of the steel shall be minimized.
--HG/T20581 (P52) 5.0.2
Two,
The selection principle of the following steels is the guiding principle of design, and should be selected according to the following conditions:
1 carbon steel for medium corrosive low pressure, low pressure vessels, the wall thickness of the medium pressure vessel, forgings, steel pipe, non pressurized components and other rigid or structural factors determine the thickness of the occasion;
--HG/T20581 (P52) 5.0.3
2 low alloy high strength steel used in medium corrosive and thick wall (≥ 8mm) pressure vessel;
--HG/T20581 (P52) 5.0.3
3 pearlitic heat-resistant steel used as high temperature resistant hydrogen or hydrogen sulfide corrosion, or design temperature of 350 degrees C ~575 c;
--HG/T20581 (P52) 5.0.3
4 stainless steel for medium corrosive environment, iron ion pollution or design temperature of more than 500 degrees Celsius or design temperature of less than -70 degrees of heat or low temperature steel;
--HG/T20581 (P52) 5.0.3
5 austenitic stainless steel, which does not contain titanium, niobium and stable chemical element, which contains more than 0.03% carbon, should be used for welding or more than 400 degrees celsius.
--HG/T20581 (P52) 5.0.3
Source: welding and cutting online WeChat Ping