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Introduction to Common Materials for High-Temperature Equipment 1. Basic requirements for metal materials at high temperatures (1) Beneficial and comprehensive high-temperature mechanical properties； (2) It exhibits good resistance to high-temperature corrosion in the appropriate working environment ； (3) Possess sufficiently good process properties such as smelting and processing capabilities ； (4) Economic feasibility tailored to the situation. 2. In addition to considering hydrogen corrosion, hydrogenation equipment must also take into account hydrogen sulfide corrosion caused by high temperatures; the inner surface of such equipment is typically lined with a stainless steel cladding layer or a stainless steel composite layer. 3. General principles for material selection: (1) When selecting steel, consideration should be given to the operating conditions of the container (such as design pressure, design temperature, properties of the medium, and operational characteristics), the weldability of the material, the manufacturing process for the container, as well as economic feasibility. (2) The maximum service temperature for steel is the upper limit temperature specified for each steel grade in the allowable stress table for steel in GB150. (3) The steel used for containers shall be accompanied by a quality certificate for the steel issued by the steel manufacturer; the container manufacturer shall inspect the steel in accordance with this certificate, and re-inspection may be conducted if necessary. If there is no steel quality certificate from the steel manufacturer or if certain items are missing, re-inspection shall be carried out in accordance with the provisions of the \"Safety Technical Inspection Regulations for Pressure Vessels\". (4) For equipment where stiffness or structural design is of primary importance, ordinary carbon steel should be used. For equipment designed primarily based on strength, steel grades such as Q235B, Q235C, 20R, 16MnR, 16Mn(HIC), 15CrMoR(H), 1.25Cr-0.5Mo-Si, 2.25Cr-1Mo, and 2.25Cr-1Mo-1/4V should be selected accordingly, taking into account constraints such as design pressure, design temperature, and the properties of the medium used. (5) Stainless steel is used in applications where the medium is highly corrosive (chemical corrosion, electrochemical corrosion) and where protection against iron ion contamination is required. (6) When selecting materials for pressure vessels, welding of dissimilar steels should be avoided as much as possible. (7) The materials of the nozzles and flanges connected to the main body should be the same as or similar to the material of the main body: the flanges should correspond to the material of the pipeline. (8) Steel for non-compressed members, when welded to compressed members, should also be a steel with good weldability and a chemical composition similar to that of the steel used for compressed members. (9) The skirt material for tower-type equipment is generally Q235B. 4. Material selection requirements for hydrogen-service pressure vessels: (1) The main material of hydrogen-service pressure vessels should be selected from Nelson’s curve against hydrogen corrosion, based on the operating temperature of the vessel (with an additional margin of about 28°C) and the designed hydrogen partial pressure. Typically, for hydrogen-service high-temperature materials, 2.25Gr-1M, 1/4V, 2.25CrlMo, 1.25Cr-0.5Mo-Si, and 15CrMoR(H) are chosen. (2) For pressure vessels operating in a medium containing hydrogen sulfide, the corrosion rate shall be determined from hydrogen sulfide corrosion curves based on the vessel’s operating temperature and the concentration of hydrogen sulfide (in volume percentage or molar percentage). When the annual corrosion rate exceeds 0.3 mm/year, more corrosion-resistant materials should be used, or stainless steel composite panels employed, or a stainless steel layer shall be welded onto the inner wall of the vessel. Furthermore, when selecting materials, the specific conditions of the medium and experience in communicative use should be taken into account. (3) When a stainless steel surfacing structure is to be used on the inner wall of the container, it should be determined whether to adopt a single-layer stainless steel surfacing structure or a double-layer stainless steel surfacing structure, based on the properties of the operating medium and the operating conditions. (4) Structural design requirements: 1) The design of the trays shall be carried out in accordance with the requirements of SH3088 \"Code for Design of Petrochemical Trays\" and JB/T1205 \"Technical Specifications for Trays\". The tray spacing is based on the upper surface of the support ring, and the positioning dimensions of the liquid seal tray are also based on the upper surface of that tray. When the material of the tray plate is carbon steel, the thickness is usually 4 mm; when it is stainless steel, the thickness is usually 3 mm. The size of the segments of the tray plates must be considered to facilitate access to the manholes. The last liquid seal disc must ensure the flow spacing of the medium. 2) The anti-impact plate of the cold exchange equipment must be placed at the medium inlet position. 3) The design of the equipment’s fire protection layer shall meet the requirement of a fire resistance limit of more than 1.5 hours. 4) For pressure vessels that require heat treatment, it should be specified that before the final heat treatment, components such as platform ladder pads, pipe support nodes, and bearing pads must be welded in place; no welding shall be carried out on the vessel after the final heat treatment. 5) For manholes on vertical equipment (except in cases with special requirements), priority should be given to the use of \"vertical lid butt-welded flange manholes\" (JB2556); for manholes on horizontal equipment (except in cases with special requirements), priority should be given to the use of \"underwater lid butt-welded flange manholes\" (JB585). (5) Any special requirements for all equipment must be specified in the drawings. When the cited standards conflict in terms, the stricter one shall prevail as a principle.