The drain pipe must be the same size as the valve outlet, and must pitch downward from the valve.
排泄管与安全阀出口必须有相同的通径，必须从安全阀开始垂直向下。
2
Both have the same pitch diameter at the top of the hole of internal threads or end of the pipe on external threads, and both have the same thread lengths or depths.
在内螺纹的孔的顶端或者外螺纹的管的端部拥有相同的中径，而且拥有相同的螺纹长度和深度。
3
These high precision instruments are more than 20 kinds and widely used for oil industry to measure the monomial parameters of taper, pitch and height screw for oil pipe, canola and drill shank.