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Material selection: Common issues related to material selection in the design review of pressure vessels include: 01 The design drawings lack the material grade or standard for the main pressure-bearing components； 02 The material standards have not been updated in a timely manner; for example, the forging standard NB/T47008-2010 should be used, but the JB4726-2000 standard is still being applied ； 03 The material condition in use does not meet the requirements; for example, there are no regulations stipulating that materials such as Q345R with a shell thickness greater than 36 mm or the inner liners of multi-layer containers made of Q345R must be used in a normalized state ； 04 For equipment that meets the requirements of 2.2.1.4.1 of the \"Safety Technical Inspection Regulations for Fixed Pressure Vessels\", there is no requirement for ultrasonic testing of each individual shell material ； 05 The shell material is Q235B steel plate; no requirements are specified regarding impact tests or the content of S and P for this material ； 06 The fittings selected for use do not meet the required conditions; for example, when the designed operating temperature of the equipment is -10°C, GB/T8163 standard fittings made of 20 steel were used ； It is inappropriate to use the GB13296-2013 standard for the material of the 07 Φ219X6 fittings, as this standard does not cover steel pipes with a diameter larger than Φ159, nor does it specify any special requirements ； 08 For the heat exchange tubes, 20 steel pipes in accordance with GB6479 standard are used; however, no high precision is required for their dimensional accuracy, and no restrictions are imposed on the S content of this material ； The heat exchanger does not specify the outer diameter tolerance and thickness tolerance of the heat exchange tubes ； For materials such as manhole covers and manhole flanges, grade IV forgings are used, and no requirement for re-inspection was proposed in accordance with the provisions of the Code for Fixed Pressure Vessels ； 10 The design uses standard components, but they do not meet the scope of application and requirements of the relevant standards ； 11 For the pipe flange bolts and nuts of containers used with explosive media, commercial-grade double-ended studs and Type I hex nuts should be used; whereas HG/T20613-rated fully threaded studs and GB/T6175 Type II hex nuts should be employed ； Bolts and nuts for container flange connections were not selected from the special-grade variety ； 12. For equipment with a design temperature of 300°C, the NBT47065-2018 leg-type supports are selected; these do not meet the standard usage conditions ； 13 The material of the saddle cushion plate should be different from that of the cylinder; the cushion plate material must be the same as that of the cylinder ； 14 In the design data sheet, if the welding material field is indicated as “determined by the welding process”, the specific welding material should be specified ； The welding material is not specified in the overall diagram, or the information regarding the welding material is incomplete.