Terms of Valve Structure and Parts

Valve terminology for its structure and parts is also important in daily operation and maintenance.

Valve Structure Terms

1. The structure length (face-to-face dimension, face-to-center dimension)
 
The distance between the inlet and outlet end faces of the valve. Or the distance from the inlet end face to the outlet axis.
 
2. Structure length of the straight-through valve (Face to face dimensions of through way type valves）
 
It refers to the distance between two planes perpendicular to the valve axis at the end of the valve body passage.
 
3. Structural length of the angle valve (angle type of valves: face to face, end to end, center to face and center to end dimensions）
 
It refers to the distance between the plane perpendicular to the axis at one end of the valve body passage and the axis at the other end of the valve body.
 
4. Structure form (type of construction)
 
It refers to the main features of various valves in structure and geometry.
 
5. Through way type
 
It refers to the valve body with the inlet and outlet axes coincident or parallel to each other.
 
6. Angle type
 
It refers to the valve body with inlet and outlet axes perpendicular to each other.
 
7. DC (Y-Globe Type, Y-Type, Diaphragm Type)
 
It refers that the passage is in a straight line, and the position of the valve stem is at an acute angle with the passage axis of the valve body.
 
8. Three-way type
 
It refers to a valve body with three passage directions.
 
9. T-pattern threeway
 
It refers that the passage of the plug (or ball) is a "T" tee.
 
10. L-pattern threeway
 
It refers that the passage of the plug (or ball) is an L-shaped tee.
 
11. The balance type (balanced type)
 
It refers to the structural form of balancing its axial force on the valve stem by medium pressure.
 
12. Lever type
 
The lever is used to drive the opening and closing parts.
 
13. Normally open type
 
When there is no external force, the opening and closing parts are in the open position automatically.
 
14. Normally closed type
 
When there is no external force, the opening and closing parts are in the closed position automatically.
 
15. Steam jacket type
 
It refers to a valve with a steam heating jacket structure.
 
16. Bellows seal type
 
It refers to a valve with a bellows structure.
 
17. Full-opening valve
 
All parts of the valve have the same inside diameter as the nominal pipe.
 
18. Reduced-opening valve
 
It refers to a valve with a reduced hole diameter of the inner flow passage.
 
19. Reduced-bore valve
 
The diameter of the inner flow passage hole of the valve is reduced, and the flow passage of the valve closing member is a non-circular valve.
 
20. One-way valve (un-directional valve)
 
It refers to a valve designed to be sealed in only one direction of medium flow.
 
21. Two-way valve (bi-directional valve)
 
The valve is designed to be sealed in both directions of medium flow.
 
22. Two-seat two-way valve
（twin-seat bi-directional valve）
 
The valve has two sealing seats, each of which can be sealed in two media flow directions.
 
23. Two-seat valve with one-way seat and two-way seat
(twin-seat, one seat un-directional and one seat bi-directional valve）
 
For a valve with two sealing pairs, when in the closed position, the two sealing pairs can keep the sealing state at the same time, and the valve body in the middle cavity (between the two sealing pairs) has an interface for releasing the medium pressure. The representative symbol is DBB.
 
24. Back seat, back surface
 
When the valve is fully open, a sealing structure prevents the medium from leaking from the stuffing box.
 
25. Pressure seal
 
Make use of the medium pressure to make the joint of the valve body and the valve cover realize automatic sealing.
 
26. Dimension of the valve stem head
 
It refers to the structural dimensions of the assembly and connection parts with the valve stem, the handwheel, the handle or other operating machinery.
 
27. Dimension of the valve stem end
 
It refers to the structural dimensions of connecting parts between the valve stem and opening and closing parts.
 
28. Dimension of connecting channels
 
It refers to the structural dimensions of the assembly connection parts between the opening and closing parts and the valve stem.
 
29. The connection form (type of connection)
 
It refers to various ways (such as flange connection, screw connection, welding connection, etc.) that are used to connect valves with pipelines or machinery and equipment.
 
Terminology of valve parts

1. Valve body
 
It refers to parts that are directly connected with pipelines (or machinery and equipment) and constitute a medium flow channel.
 
2. Bonnet (cover, cap, lid)
 
It refers to the main parts connected with the valve body and forming the pressure chamber with the valve body (or through other parts such as the diaphragm, etc.).
 
3. Opening and closing parts (disc)
 
It is a general term for a part used to cut off or regulate the medium circulation, such as the gate valve, the valve disc in the throttle valve, etc.
 
4. Disc
 
It refers to the opening and closing parts in stop valves, throttle valves, check valves, etc.
 
5. Seat (body seat ring, shoulder seat, bottom seat)
 
It refers to parts installed on the valve body and forming a sealing pair with the opening and closing parts.
 
6. Sealing surface
 
It refers to the opening and closing parts that are closely attached to the valve seat (valve body), and the two contact surfaces play a sealing role.
 
7. Valve stem
 
It refers to the main parts that transmit the opening and closing force to the opening and closing parts.
 
8. Yoke bushing (yoke nut)
 
It refers to parts that form a kinematic pair with valve stem threads.
 
9. Filling box
 
It refers to a structure in which the valve cover (or valve body) is filled with packing to prevent the medium from leaking from the valve stem.
 
10. Stuffing box
 
It refers to stuffing the packing to prevent leakage of medium from the valve stem.
 
11. Packing gland (gland, gland flange, PNE-piece gland)
 
It refers to parts for pressing packing to achieve sealing.
 
12. Packing (packing rings)
 
It is used to fill the stuffing box to prevent the leaking stuffing at the double valve stem of the medium.
 
13. Packing seat (packing washer)
 
It refers to parts that support packing and keep packing sealed.
 
14. The yoke (yoke)
 
On the valve cover or valve body, it refers to the parts used to support the valve stem nut and transmission mechanism.
 
15. The handwheel (impact handwheel, hammer blow handwheel）
 
It refers to the handwheel structure using impact force to reduce valve operating force.