阀门作为流体控制系统的核心部件，其质量直接影响管道系统的安全运行，合格检验需覆盖外观、性能、材质等多维度，通过科学检测方法确保各项指标符合使用要求。

　　As the core component of fluid control systems, the quality of valves directly affects the safe operation of pipeline systems. Qualification inspection needs to cover multiple dimensions such as appearance, performance, and material, and ensure that all indicators meet the usage requirements through scientific testing methods.

　　外观检验是合格判定的基础环节。首先检查阀体表面是否存在裂纹、缩孔、砂眼等铸造缺陷，这些缺陷会导致介质泄漏或结构强度下降，可借助放大镜（放大倍数不低于 10 倍）仔细观察关键部位（如阀盖与阀体的连接面、密封面）。其次核查尺寸精度，用卡尺测量法兰厚度、螺栓孔间距等关键尺寸，误差需控制在设计标准的 ±0.5 毫米范围内，确保安装时与管道匹配。此外，密封面的光洁度是重点，平面密封面需达到 Ra1.6μm 以上的粗糙度，锥形密封面的角度偏差不超过 ±1°，可通过标准样板贴合检查，透光间隙不得超过 0.03 毫米。

　　Appearance inspection is the fundamental step in determining qualification. Firstly, check the surface of the valve body for casting defects such as cracks, shrinkage cavities, sand holes, etc. These defects can cause medium leakage or a decrease in structural strength. Key parts (such as the connection surface and sealing surface between the valve cover and valve body) can be carefully observed with a magnifying glass (magnification not less than 10 times). Next, verify the dimensional accuracy by measuring key dimensions such as flange thickness and bolt hole spacing with calipers. The error should be controlled within ± 0.5 millimeters of the design standard to ensure compatibility with the pipeline during installation. In addition, the smoothness of the sealing surface is the key. The flat sealing surface should have a roughness of Ra1.6 μ m or more, and the angular deviation of the conical sealing surface should not exceed ± 1 °. It can be inspected by bonding with a standard template, and the light transmission gap should not exceed 0.03 millimeters.

　　压力试验是验证密封性能的核心手段。强度试验需将阀门内腔充满水（或其他试验介质），缓慢升压至公称压力的 1.5 倍，保压时间根据阀门规格确定（DN100 以下阀门保压 10 分钟，DN100 以上保压 30 分钟），期间不得出现渗漏或结构变形。密封试验分壳体密封和填料密封两项：壳体密封试验压力为公称压力的 1.1 倍，保压 5 分钟后检查阀体与阀盖的连接部位；填料密封试验则在阀门全关状态下施加公称压力，观察阀杆处是否有介质渗漏，气泡逸出量每分钟不得超过 3 个（以气体为试验介质时）。对于高温高压阀门，还需进行高温密封试验，在设计温度下保持压力稳定，确保密封性能不受温度影响。

　　Pressure testing is the core means of verifying sealing performance. The strength test requires filling the valve chamber with water (or other test medium), slowly increasing the pressure to 1.5 times the nominal pressure, and maintaining the pressure for a time determined by the valve specifications (10 minutes for valves below DN100 and 30 minutes for valves above DN100). During this period, there should be no leakage or structural deformation. The sealing test is divided into two parts: shell sealing and packing sealing. The pressure for the shell sealing test is 1.1 times the nominal pressure, and after holding for 5 minutes, the connection between the valve body and the valve cover is checked; The packing seal test applies nominal pressure when the valve is fully closed, and observes whether there is medium leakage at the valve stem. The amount of bubbles escaping per minute should not exceed 3 (when using gas as the test medium). For high-temperature and high-pressure valves, a high-temperature sealing test is also required to maintain pressure stability at the design temperature and ensure that the sealing performance is not affected by temperature.

　　材质检验需验证材料成分与力学性能。通过光谱分析仪检测阀体、阀瓣的材质成分，确保与设计要求一致（如不锈钢阀门的铬镍含量需符合对应牌号标准），防止以次充好。力学性能测试包括硬度和拉伸试验，截取阀体试样进行硬度检测（如铸铁阀门硬度需在 170-230HB 范围内），拉伸试验则需满足规定的抗拉强度和伸长率指标，避免因材质强度不足导致使用中出现断裂。对于用于腐蚀性介质的阀门，还需进行耐腐蚀试验，将样品浸泡在对应介质中（如 3% 氯化钠溶液），24 小时后检查表面腐蚀程度，失重率不得超过规定标准。

　　Material inspection requires verification of material composition and mechanical properties. By using a spectral analyzer to detect the material composition of the valve body and valve disc, it is ensured that they are consistent with the design requirements (such as the chromium and nickel content of stainless steel valves must comply with the corresponding brand standards), to prevent inferior products from being used as good ones. Mechanical performance testing includes hardness and tensile tests. The valve body sample is taken for hardness testing (such as cast iron valves, whose hardness needs to be within the range of 170-230HB). The tensile test must meet the specified tensile strength and elongation indicators to avoid fracture during use due to insufficient material strength. For valves used in corrosive media, a corrosion resistance test is also required. The sample should be soaked in the corresponding medium (such as 3% sodium chloride solution), and the surface corrosion degree should be checked after 24 hours. The weight loss rate should not exceed the specified standard.

　　操作性能检验关注启闭灵活性与精度。手动阀门需测试启闭扭矩，在全程启闭过程中，扭矩应均匀变化，无卡阻现象，最大扭矩不得超过标准值（如 DN50 闸阀的启闭扭矩不超过 30Nm）。电动或气动阀门则需检查驱动装置的响应速度，从全开到全关的时间应符合设计要求，且在断电或断气时能可靠处于安全位置（如自动关闭或保持原位）。对于调节型阀门，需通过流量测试装置验证流量特性曲线，实际曲线与理论曲线的偏差不得超过 ±5%，确保调节精度满足系统控制需求。

　　Operational performance testing focuses on the flexibility and accuracy of opening and closing. Manual valves need to be tested for opening and closing torque. During the entire opening and closing process, the torque should vary uniformly without any jamming, and the maximum torque should not exceed the standard value (such as the opening and closing torque of DN50 gate valves not exceeding 30Nm). Electric or pneumatic valves need to check the response speed of the driving device. The time from fully open to fully closed should meet the design requirements, and they should be able to be reliably in a safe position (such as automatically closing or maintaining their original position) when power or gas is cut off. For regulating valves, the flow characteristic curve needs to be verified through a flow testing device. The deviation between the actual curve and the theoretical curve should not exceed ± 5% to ensure that the regulating accuracy meets the system control requirements.

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