difference between a double seated and single seated globe valves

 Double Seated and Single Seated

What is the difference between a double seated and single seated globe valves.

Single seated globe valves

Large amount of force required to drive the stem

Double seated globe valves

Stem can be driven with small amount of force

Single seated globe valves

Tight shut off 

Double seated globe valves

Can not achieve perfect closure resulting in leakage 

Single seated globe valves

Used in small diameter applications

Double seated globe valves

Used in larger diameter applications 

Single seated globe valves

Used for controlling large range of process parameters hence used in oil and gas production, power generation

Double seated globe valves

Used for high flow and high pressure services

Single seated globe valves

Single seated valves are used in case of higher shut-off and the pressure range is low compared to a double-seated valve.

Double seated globe valves

Double seated valves are pressure balanced and can be used for high-pressure applications.

Single seated globe valves

in this type of valves the process pressure would reach on the bottom side of the plug and this will create a force upward in the valve stem. 

Double seated globe valves

In this type of valve, the line pressure acts upward in one plug and downward in the other, and because of this, the force is balanced. 

Single seated globe valves

 A single-seated valve has a single seat and a single plug

Double seated globe valves

A double-seated valve is a top and bottom guided valve and these valves have two plugs and two seats.

What is difference between single seated and double seated control valve?

Single seated control valve

Single seated control valve has only one trim and one seat

Double seated control valve

double seated control valve has two trims and two seats.

Single seated control valve

Single seated control valve has a small leakage, and it is easy to achieve strict sealing and cutting

Double seated control valve

Double seated control valve has a large leakage.

Single seated control valve

Single seated control valve allows a small differential pressure

Double seated control valve

Double seated control valve is subjected to a small unbalance force and allows a large differential pressure.

Single seated control valve

Single seated control valve has a small flow capacity, and double seated control valve has a large flow capacity. Compared with other control valves of the same diameter, double seated control valve can flow through more fluid, and the flow capacity of the same diameter 

Double seated control valve

double seated control valve is about 20%-50% larger than that of single seated control valve.

Single seated control valve

Due to the large thrust of the fluid medium to the valve trim, that is, the unbalanced force is large, therefore, in the application of high pressure difference and large diameter, it is not suitable to use a single seated control valve

Double seated control valve

Double seated control valve is not suitable for high pressure differential applications. Due to complex flow path, it is not suitable for the control of fiber containing media and high viscosity fluids.

What are the features of single-seated valves?

• These valves have a good flow capacity
• Tight shut-off
• Good rangeability
• Turndown is high and it is the ratio between the maximum and minimum controllable flow rate

What are the advantages and disadvantages of a single-seated valve?

Advantages

• It provides high rangeability and tight shut-off
• A reversible plug is available

Disadvantages

• A large actuator is needed
• Pressure recovery is low
• Only used for small diameter applications
• The force required to drive the stem is high

What are the applications of single-seated valves?

• These valves are used to control a large range of process parameters and because of this feature
• it is used in oil and gas production
• power generation.

What are the features of a double-seated valve?

• A small force is needed to move the stem
• It can be used in large diameter applications
• Flow can be diverted

What are the advantages and disadvantages of a double-seated valve?

Advantages

•  It can be used for larger valves
•  It can be used for high flow and high-pressure services

Disadvantages

• Tight shut off is not possible
• Due to the erosion and cavitation, the body parts could wear out