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1. The inspector must fully understand and be familiar with the contract, technical requirements, and any special requirements for this batch of control valves. Familiarize yourself with and master the types, drawings, and technical specifications of these control valves. Understand and become familiar with the test plan for regulating valves provided by the supplier. 2. The inspector shall inspect and audit the supplier of control valves’ quality control procedures. Ensure that the supplier’s quality control procedures guarantee the quality of this batch of control valves. 3. The control valve consists of a valve body and an actuator. The inspector requires the supplier to inspect the valve body castings or forged blanks arriving at the factory with regard to their visual quality, minimum thickness, structural length, etc., in accordance with the specifications, and the inspector shall witness such inspections. The inspector reviews the raw material quality certificates, chemical composition, heat treatment, and mechanical properties of the blanks to ensure compliance with specifications and contractual technical requirements. If an RT requirement is specified in the contract, the inspector will review the supplier’s wafers and the RT report. 4. Conduct a visual quality inspection of components in the actuator section, such as positioners, converters, solenoid valves, diaphragms, springs, limit switches, and pressure relief valves, and review the warranty documents and certificates of conformity for each component. And whether it is the brand specified in the contract. 5. During the mechanical processing and assembly of the valve body, inspectors must verify the machining dimensions of the valve. Inspect and verify the material and visual quality of the valve internals to ensure compliance with the contractual technical requirements, and also check and confirm the sealing type and sealing materials of the valve to ensure they meet the contractual technical specifications. 6. After the valves are assembled, each valve is subjected to pressure and sealing tests; the sealing tests include high-pressure sealing and low-pressure sealing. The inspector witnesses the testing process. Review the valve dimensions against the manufacturing drawings. 7 For valves that require painting, the inspector will check the quality of rust removal on the valve body prior to painting. Ensure the quality of paint adhesion on the valve body. Check the thickness and visual quality of the valve seat paint. 8 The inspector checks the assembly of the actuator, ensuring that the type of actuator used meets the technical requirements specified in the contract. 9 After the valve body and actuator have been assembled, each control valve is subjected to pre-shipment inspection in accordance with the standard GB/T4213—2008. This inspection includes tests for parameters such as the basic error of the control valve, hysteresis, dead zone, deviation from the set point, deviation from the rated stroke, leakage rate, sealing performance, pressure resistance, appearance, rated flow coefficient, inherent flow characteristics, vibration resistance, and service life. The measured data are compared with the technical design data. If it meets the criteria, it will be approved; if not, it will be rejected. The inspector conducts full inspection and oversight throughout the process. 10 The inspectors will review the process documents and handover documents related to the control valve, which generally include quality certificates for the raw materials used in various components of the valve, test reports, product quality certificates, relevant inspection reports, manufacturing drawings, etc. The specific contents to be reviewed are determined in accordance with the requirements of the contract. 11 After the control valve passes the inspection, the inspector checks the packaging quality of the valve prior to shipment. Once the supplier’s packaging meets the specifications and the technical requirements outlined in the contract, the inspector gives approval for shipment.