High Pressure Oil Pipe Knot Thread Model

The letters S\D\L of the high pressure oil pipe joint model all represent the size.

DN is the nominal diameter (or nominal diameter), which is the general diameter of various pipes and pipeline accessories. Pipes and pipeline accessories of the same nominal diameter can be connected to each other and are interchangeable.

Size standard is European flange
There are 10 pressure grades such as PN 0.25, 0.6, 1.0, 1.6, 2.5, 4.0, 6.3, 10.0, 16.0, 20.0 and so on.
Nominal diameter: DN15~DN1600mm.
There are 5 types of sealing surface: flat surface, convex surface, concave-convex surface, tongue and groove surface, and ring connection surface.
Nominal diameter, also known as mean outside diameter.
This is because the tube wall of the metal tube is very thin, and the outer diameter of the tube is almost the same as the inner diameter of the tube, so the average value of the outer diameter of the tube and the inner diameter of the tube is used as the tube diameter.
DN is the nominal diameter, and the nominal diameter (or nominal diameter) is the general diameter of various pipes and pipeline accessories. Pipes and pipeline accessories of the same nominal diameter can be connected to each other and are interchangeable. It is not the outer diameter of the pipe or the inner diameter of the pipe in the actual sense, although its value is close to or equal to the inner diameter of the pipe;
For example, welded steel pipes can be divided into thin-walled steel pipes, ordinary steel pipes and thickened steel pipes according to thickness. Its nominal diameter is neither the outer diameter nor the inner diameter, but a nominal size that approximates the inner diameter of ordinary steel pipes. Each nominal diameter corresponds to an outer diameter, and its inner diameter varies with thickness.
The nominal diameter can be expressed in metric mm or in imperial in. Pipe accessories are also expressed by nominal diameter, which is the same as the seamed pipe.