VALVES (2)

Technical

Supex 2024. 7. 22. 13:12

The most commonly used type among check valves.
The disc comes into contact with the body seat in a flat manner, and the disc opens and closes by rotating through the arm and rod pin in a simple structure.
Relatively easy to manufacture and can be made from low to high pressure, and from small to large sizes.
Comparatively low pressure loss.
High noise can occur when closing due to the flat contact of the disc with the body seat, or noise can occur due to disc chattering.
Not recommended for use in vertical lines.

The disc rotates through the rod pin and makes contact with the body seat in a cone shape while opening and closing.
Like the swing check valve, it is widely used from low to high pressure and from small to large sizes.
More difficult to manufacture than swing check valves, resulting in higher costs.
Less noise when closing, and significantly less disc chattering.

Relatively easy to manufacture, with a quick open form similar to the T-type of globe valves.
Good tightness but has high pressure loss, which is a disadvantage of globe valves.
Noise can occur due to disc chattering.
Should only be used in horizontal piping.
Generally supplied up to DN80 diameter.

Low noise due to disc chattering.
Soft seats provide good sealing but are difficult to use at high temperatures, while metal seats have less sealing performance.
Relatively cheaper than swing check valves.

Used for the same service as gate valves, i.e., open and close, but with a taper plug instead of a disc.
Uses a wrench instead of a hand wheel.
Low pressure loss, mainly used for low temperature, low pressure fluids.
For lubricated types, grease is supplied through grooves installed in the body and plug to ensure smooth operation and enhance sealing effect.
Should be used with fluids where grease absorption is not an issue.

Essentially lightweight and thin structure.
For non-lubricated types, the usage condition should be within the temperature limits of the lining sleeve material, such as Teflon.
Currently, non-lubricated type plug valves are widely used.

The valve opens and closes by rotating a ball with a through hole that aligns with the center of the flow path inside the body.
The body has seat rings that come into contact with the ball.

Used for the same service as gate valves, i.e., open and close, with a ball instead of a plug, and using a hand wheel or wrench.
Excellent operability.
Particularly used as a block valve for tight sealing (e.g., in gas plants).

Can be fully opened and closed using a plate in a cylindrical body, making it suitable for both on-off service and flow throttling.
Rubber seats are used for low specifications, low temperature, and low pressure.
High specification valves with Teflon or metal seats are used mainly for high temperature and high pressure process lines.

Relatively lightweight, easy to install and handle compared to other valves.
Can be installed in confined spaces.
Quick emergency opening and closing, and easy operation with a quarter turn.
Easy to enlarge and automate, with low costs.
Simple structure, making maintenance easy.
Concerns about seat damage due to rotational friction between seats.
Limited by temperature and pressure conditions.
Significant variability in seat material properties depending on the fluid used.
Risk of seat deformation when maintained for a long time.

Classified by end type: Wafer Type, Lug Type, Double Flanged Type
Classified by seat material: Rubber Seat (NBR, EPDM, VITON), Teflon Seat (PTFE, RTFE), Metal Seat (Stainless, Inconel, Monel)
Classified by structure: Concentric, Eccentric, Triple Offset

Uses an elastic diaphragm to seal against the seat and block fluid flow.
The valve body includes a seat area and is coated with plastic or corrosion-resistant materials.
High resistance to corrosive liquids.
The diaphragm can be damaged by repeated loads or sharp foreign objects in the fluid.

Designed to prevent leakage by using a flexible hose (bellows) to seal the packing area of the stem, which can lose its original function due to high temperature, high pressure, long-term use, and compression wear.

A type of globe valve where the flow turns 90 degrees instead of being straight.
Uses a hand wheel to control the flow.
Mainly used in high-pressure lines.

Widely used in piping to protect equipment and pipelines from excessive internal pressure.
Contains a spring that automatically opens the valve when the set pressure is exceeded.
Safety valves have similar functions to relief valves.
Relief Valve: Opens and closes proportionally with pressure changes, used in water and oil lines.
Safety Valve: Fully opens when pressure exceeds a certain limit and closes when pressure drops, used in gas and steam lines.

Uses a hydraulic or pneumatic actuator attached to a globe or butterfly valve for automatic opening and closing.
Regulates the amount and pressure of fluid.
Equipped with a diaphragm.
Actual design is provided by the instrument group.

With the valve partially open, fill the valve body with water to ensure no air remains, block both ends of the valve, tighten the packing to prevent leakage, and apply the test pressure specified in ASME B16.34. Maintain the pressure for the duration specified in ASME B16.34 and check for external body leaks.

Apply a test pressure specified in ASME B16.34, at least 110% of the Cold Working Pressure (CWP) for manual valves, or at least 110% of the operating or differential pressure with customer consent for Motor Operated Valves (MOVs). Maintain the pressure for a specified time and check for seat leakage.

Fully open the valve and backseat it, loosen the gland packing, fill the valve body with water to ensure no air remains, and apply the test pressure specified in ASME B16.34 for a specified time to check for leaks