Basic knowledge of valves that everyone should know

Valve Foundation

1. The basic parameters of the valve are: nominal pressure PN, nominal diameter DN

2. Basic functions of the valve: cut off and connect the medium, adjust the flow and change the flow direction

3. The main methods of valve connection are: flange, thread, welding and clamp

4. The pressure temperature grade of the valve indicates that the maximum allowable non impact working pressure is different under different materials and working temperatures

5. There are mainly two systems of pipe flange standards: European system and American system.

The pipe flange connection dimensions of the two systems are completely different and cannot be matched with each other;

It is most appropriate to distinguish by pressure level:

The European system is pN0 25、0.6、1.0、1.6、2.5、4.0、6.3、10.0、16.0、25.0、32.0、40.0MPa;

The US state system is PN1 0(CIass75)、2.0( CIass150)、5.0( CIass300)、11.0(CIass600)、15.0( CIass900)、26.0( CIass1500)、42.0( CIass2500)MPa.

The types of pipe flanges mainly include: integral (if), plate flat welding (PL), flat welding with neck (so), butt welding with neck (WN), socket welding (SW), screw (th), loose sleeve of butt welding ring (PJ / SE) / (LF / SE), loose sleeve of flat welding ring (PJ / RJ) and flange cover (BL).

Flange sealing surface types mainly include: full plane (FF), raised surface (RF), concave (FM), convex (m) surface, tenon (T) groove (g) surface, ring connection surface (RJ), etc.

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