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Guidelines for the Design and Calculation of Superheated Steam Piping I. Design Basis and Pipeline Classification Core specifications: Comply with TSG 31-2025 \"Technical Regulations for the Safety of Industrial Pipelines\", GB/T 20801 \"Code for Pressure Pipelines – Industrial Pipelines\", DL/T 5054 \"Technical Specifications for the Design of Steam and Water Pipelines in Thermal Power Plants\", and GB 50316 \"Code for the Design of Industrial Metal Pipelines\". Pipeline grade: With a design pressure of 1.2 MPa (<6.3 MPa) and a temperature of 250°C (<400°C), it belongs to GC2 class industrial pipelines. II. Pipe material selection and wall thickness calculation: Seamless steel pipes (such as 20# steel) are used, as they are suitable for the specified temperature and pressure conditions. The outer diameter corresponding to a DN350 pipe is 377 mm. Wall thickness calculation (pipe strength calculation): (omitted) Parameter example: Taking 20# steel as an example, the allowable stress at 225°C is used as a reference, with corrosion allowance taken into account (generally not less than 1.5 mm). The final wall thickness must be rounded to the standard specification and ensured to meet the requirements for pressure pipelines. III. Thermal Compensation and Stress Analysis: Thermal displacement – the formula for calculating the thermal expansion of pipes (omitted; accurate calculation is required) is used to determine the length of pipe supports. Compensation design: Natural compensation is given priority: by optimizing the layout of the pipes (such as in L-shaped, Z-shaped, or Π-shaped arrangements), the flexibility of the pipes themselves is utilized to absorb thermal displacements. Selection of compensator: When natural compensation is insufficient, a square compensator or a bellows compensator can be used. Ensure sufficient free arm length during setup. Stress analysis: Specialized software (such as CAESAR II) must be used to conduct stress analysis of pipes, in order to evaluate primary stresses (resulting from continuous loads such as internal pressure and weight) and secondary stresses (thermal expansion stresses). This ensures the flexibility of the piping system and keeps the thrusts and moments on the equipment connections within acceptable limits. IV. Pipeline Layout and Support/Brace Design – Key Points for Overhead Installation: Pipelines should be laid along supports, taking into account a safe distance from other pipelines or structures. Support and hanger installation: Fixed supports (to bear thrust), sliding supports (to bear gravity), guide supports (to restrict radial displacement), and spring supports and hinges (to accommodate vertical thermal displacement) are installed based on the results of stress analysis. More spring supports are not necessarily better; it is necessary to ensure the stability of the piping system, paying special attention to the pipes connected to the equipment. V. Safety and auxiliary facilities – drainage system: Start-up drainage and regular drainage devices should be installed at the lowest points of the pipelines, in areas where water tends to accumulate during startup (such as in front of and behind valves), and at regular intervals (such as every 150–200 meters) to prevent water hammer. Pressure relief device: A safety valve should be installed in an appropriate location as overpressure protection. Insulation design: A composite insulation structure is used (such as a combination of high-temperature resistant glass wool/alumina fiber mats and polyurethane foam), and the thickness of the insulation layer must be determined through thermal calculations to meet the requirements regarding heat loss. VI. Summary: This plan outlines the key aspects of the design calculations for DN350 superheated steam pipes (250°C, 1.2 MPa), including the regulatory standards applied, wall thickness of materials, thermal compensation, stress analysis, supports and hangers, as well as safety measures.