The plug valve and the globe valve have their own superior performance, but they also have some differences, such as components and so on. The following will introduce to you.

Plug Valves

1.What are they?

The plug valve is an angular stroke rotary motion manual valve with a cylindrical or conical rotary plug inside. It allows or prevents fluid straight-through flow through the valve body by rotating the rotary plug. A plug valve provides a straight passage through the port so fluid can flow through the open plug with minimal turbulence. It has one or more horizontal channels to allow flow through the valve when open. Plug valves are often used to move liquids or gases but rarely solids. Flow can be either fully open or fully closed in either direction. In addition, plug valves are simple and generally economical.

2.Parts

The typical plug valve consists of a body, bonnet, stem, and plug.

(1) Plug

The plug is the opening and closing part of the plug valve, which is cylindrical or conical. Cylindrical cocks have a rectangular or circular channel section, and conical cocks have a rectangular, trapezoidal or circular channel section. These shapes make the structure compact and lightweight, but cause a certain pressure drop.

(2) Stem

The stem of the valve connects the disc with the actuator. It helps the movement of the actuator to the plug disc so as to open or close the plug disc. The plug valve has a small stem that connects to the disc.

(3)The Plug Valve Body

The body connects to the pipes through an end connection.

Globe Valves

(1)What are they?

The globe valve is a forced sealing valve. It refers to a valve where the closing member (disc) moves along the centerline of the valve seat. The opening and closing parts of the globe valve are plug-shaped discs. It’s sealing surface is flat or conical, and the disc moves linearly along the center line of the valve seat.

(2)Parts

The typical globe valve composes of a body, bonnet, stem, disc, seat and basket.

1.Body

The globe valve body is the main pressure-bearing structure of the valve,which is easy to identify because it constitutes the mass of the valve. It contains all the internal parts of the valve that touches with the substances that the valve controls. The valve cover is connected to the valve body and contains the fluid, gas or slurry.

2.Seat

Seat rings provide a stable, uniform and replaceable closing surface. The valve seat is usually screwed in or screwed in. This pushes the cage down against the lip of the seat and secures it securely to the body.

3.Stem

The stem of globe valve links the actuator with the inside of the valve and transmits the driving force. The stem of the actuator control valve is smooth and the stem of the manual valve is threaded.

4.Bonnet

The bonnet is ready for a leak-proof closure to the valve body. The threaded portion of the stem goes through a hole in the bonnet with matching threads. Globe valves may have a screw-in, union or bolted bonnet.

Differences

1.The sealing performance of the plug valve is better than that of the globe valve.

2.Globe valves are better than plug valves for flow through.

3.The globe valve has a long stroke and slow opening speed. The plug valve is used for frequent operation, and it opens and closes quickly and easily.

4.Due to the change in the flow direction of the medium through the valve, the small flow resistance of the globe valve is high. The fluid resistance of the plug valve is small.

5.The plug valve is simple in design and low in cost.

Plug valves are often used on low-temperature, low-flow pipelines because their spool seals are sensitive to high temperatures. The use of globe valves is extremely common, but due to the large opening and closing torque and the long structure length, the nominal diameter is usually limited to less than 250mm, and some are up to 400mm, but special attention should be paid to the direction of inlet and outlet when selecting. Generally, most of the globe valve medium below 150mm flows in from the bottom of the valve disc, and most of the globe valve medium above 200mm flows in from the top of the valve disc. This is due to the closing torque of the valve. In order to reduce the opening or closing torque, generally more than 200mm globe valves are equipped with internal bypass or external bypass valve.

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