结构细节
DESIGN DETAILS

美国尼伯科Sure Seal®（稳密）高性能蝶阀是双偏心（双偏移）结构。这种结构在阀瓣运转过程中，通过减少阀座对阀瓣的阻扰，最大程度降低扭矩，增加阀门工作寿命。可提供符合美国机械工程师协会ASME压级150（类似通径DN50 - DN900）和压级300（类似通径DN50 - DN600）的对夹型和凸耳型结构蝶阀。美国稳密蝶阀是双向结构，但是提供一个推荐的流向，并且清晰标注在阀体上。

The NIBCO® Sure Seal® High Performance Butterfly Valve is a double eccentric (double offset) design. This design minimizes torque and increases valve service life by decreasing seat to disc interference throughout the disc travel. Valves are available in wafer and lug design for ASME Class 150# (2”-36”) and Class 300# (2”-24”). The valve is bi-directional by design but has a recommended flow direction which is clearly marked on the valve body.

安装前的检查和准备工作
PRE-INSTALLATION INSPECTION AND PREPARATION

在把阀门安装到管线之前，建议按照下列步骤检查阀门：

Before installation of the valve into the pipeline, it is recommended to inspect the valve as follows:

1. 检查是否有在运输过程中造成的任何损坏。
   Check for any damage that might have occurred during shipping.
2. *查看阀门上的金属标签，确保阀门结构、压力等级以及阀门结构材质符合使用要求。
   *Review metal tag attached to valve to ensure design, pressure class, and material of construction meet required application.
3. 从阀门外表拆卸保护层，清洗或清除阀门机加工表面的任何外部颗粒。这是垫圈密封区域，要保持清洁，以确保安装后实现正确的密封。
   Remove the protective covers from the face of the valve, and clean or remove any foreign particles from the machined face of the valve. This is the gasket sealing area and keeping it clean will ensure proper sealing after installation.
4. 反复几次开关阀门，确保调整后的定位装置能够进行全部的运转定位。按逆时针方向开启阀门，顺时针方向关闭阀门。阀门的止动装置是阀门结构整体的一部分，用来阻止阀门顺时针旋转时的过转现象。这种止动装置不应该用于关闭调节。如果阀门阀瓣接触到止动装置，说明阀瓣所在位置已经超过最佳密封位置。
   Cycle the valve from the closed to fully open position to ensure that travel stops are adjusted to provide complete travel. The valve operates counter-clockwise to open and clockwise to close. A disc stop is an integral part of the valve design to stop over travel in a clockwise rotation. This stop should not be used for closure adjustment. If the valve disc is in contact with the stop the disc has traveled beyond the optimal sealing position.
5. 关闭阀门。在安装过程中，阀门应该处于关闭状态，以防止损伤阀瓣密封面。
   Close valve. The valve should be in the closed position during installation to prevent damage to the disc sealing surface.

*  注：每一个美国尼伯科稳密高性能蝶阀上附加的金属标签标记着阀门通径、压力等级和结构材质。还有第二个标签标记着独立的系列号，用于追踪阀门有关压力测试、组装日期和材料测试报告。

*  Note: The metal tag affixed to every NIBCO Sure Seal High Performance Butterfly Valve is equipped with the valve size, pressure class and materials of construction. A second metal tag with an individualized serial number is also attached to allow tracking of the valve with regard to pressure test, assembly date and material test reports.

管线检查和准备工作
PIPELINE INSPECTION AND PREPARATION

1. 清除管线内任何外部物质，例如锈斑、焊渣、或焊线。
   Remove any foreign materials such as rust, welding slag, or welding wire from the pipeline.
2. 清洁管道法兰，确保良好的垫圈接触。
   Clean the pipe flange to ensure good gasket contact.
3. 检查管道和管道法兰内径，确保适当的阀瓣间隙。
   Check pipe and pipe flange I.D. to ensure adequate disc clearance.