Gate Valves

GATE VALVES

Gate valves are made following the ASME B16.34 / API602 standards. Gate valves are low pressure valves used to stop fluid flow. The gate valve is designed with a gate or wedge type disc to control the valve opening or closure. The gate valves have a wheel-shaped handle with seat sealing in metal to metal. Gate valves are used for various applications and come in different types.

Gate valves are available in sizes ranging from 3/4” to 6”. The materials used for gate valves are Forged Steel A105, Cast Steel, Stainless Steel SS316, and Cast Iron. Gate valves can withstand working pressure between 150#, 200#, and 800#. For gate valves, various end connection types are used.

Material Specification	Cast Steel Cast Iron Forged Steel A105 Stainless Steel SS316
Connection Type	150# Flange End Threaded End (BSPP / NPT) Welded End Socket Weld JIS10K Flange End
Size	3/4” to 6”
Working Pressure	150# 200# 800#

Gate Valves Specifications

To learn more about individual product specification, please read the details below:

ANSI 150# SS316 Gate Valve

JIS 10K SS316 Gate Valve

Threaded End SS316 Gate Valve (200 PSI)

Threaded End SS316 Gate Valve (800 PSI)

ANSI 150# Cast Iron Gate Valve

JIS 10K Cast Iron Gate Valve

ANSI 150# Cast Steel Gate Valve

ANSI 150# Forged Steel Gate Valve

Threaded End Forged Steel Gate Valve

Welded End Forged Steel Gate Valve

1. What is the function of Gate Valve?

Gate valves are low pressure valves used to shut down the flow of fluid in systems. The gate ball valve is made following the ASME B26.34 / API602 and available in sizes ranging from 3/4” to 6”. Working pressure for gate ball valves varies, however, the maximum pressure is 800#. Gate valves are made of various materials such as cast Iron, stainless steel SS316, cast iron, and forged steel.

Gate valves are mainly designed to block the flow of process fluids in a system installation. They are either placed in a fully opened or fully closed position. Gate valves are low pressure valves designed to have a maximum pressure rating of 150 PSI. The valve is designed with a wedge type disc or gate placed at the center of the valve and it blocks process fluid from flowing through the valve.

The gate valve is designed as a multi-turn valve, that is, the transformation from opened to closed position occurs after multiple turns which allow a slow movement to avoid water hammer effects. The threaded stem does this and this is the place for the upward and downward movement of the gate during operation. Gate valves are used in different industries using fluid services such as hydrocarbons, air, fuel, steam, lube oil, and steam.

Ansi 150# Cast Steel Flange End Gate Valve

2. What is a Gate Valve used for?

Gate valves are linear motion valves and are mostly applied in plant processing. The gate valve is detached whilst the valve is fully opened. A normal gate valve does not block fluid during flow. This reduces the rate of pressure loss and the creation of a free bore. Also, after the valve is fully closed, tight-sealing only occurs when the disc and seats achieve a 360⁰ surface contact.

Gate valves aren’t suitable to serve as control or regulating valves because the precision of flow control is unrealistic. When the valve is partly opened, the flow rate is at a high velocity which may result in erosion of the disc and the seating surface. When this happens, the vibration and sound rate increases drastically.

Gate valves are produced in different body types. These types are enumerated below:

Type of Body Bonnet Joint	Type of Disc	Type of Stem Movement
Bolted bonnet Pressure sealed bonnet Screwed bonnet Welded bonnet	Split wedge or parallel disc valve Solid taper wedge Flexible wedge	Non-rising stem type Rising stem or Y type and OS type (Outside stem and Screw end type)

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3. How do you identify a Gate Valve?

The gate valve is shaped like a wedge or knife and it is higher than the globe valve when fully opened; however, the gate has a smaller face to face length dimension. There are several types of gate valve bonnet as per below:

Type of Body Bonnet Joint	Features
Bolted Bonnet	A gasket is required to seal the joint between body and bonnet Popular and large number of design
Pressure sealed bonnet	The higher the body cavity pressure, the greater the force on the gasket in a pressure sealing Apply in a high pressure system Apply in high temperature application
Screwed bonnet	Inexpensive valve design Simple design
Welded bonnet	Lighter in weight than bolted bonnet counterparts Popular design where disassembly is not required

4. Which is a type of Gate Valve?

There are three major types of gate valves. They are:

Solid taper wedge: the solid taper wedge is the commonly used type of gate valve due to its simplicity and strength. Any valve with this solid taper wedge is very flexible and fit to be installed in any position as required by the system. However, one major drawback of the solid taper wedge is changing seat alignment as the pipe load increases. More so, this type is prone to leakages of fluid and when exposed to high temperature, the wedge is susceptible to thermal locking. Thermal locking is a term used to define a state of wedge disc getting stuck between valve seats and expanding the metal. Solid taper wedges are best used for low pressure to moderate temperature systems.

JIS 10K Cast Iron Gate Valve

Flexible wedge: the flexible wedge is a piece of a solid disc with an edge cut. This cut differs according to sizes, shape, and deepness. For example, a shallow edge cut reduces the flexibility and sustains the valve's strength, while a wider or cast-in recess has more flexibility. Also, the cast-in recess cut has reduced leakage rate and improved seat alignment. It is recommended to be applied in thermal binding as it boosts performance. Thermal binding occurs when the wedge disc is trapped in a close position. One of the primary causes is when a cool valve stem is placed in a hot valve. When this happens, the stem is heated up and expands more, thereby increasing the force of the seat when the torque is closed. A major drawback of the flexible wedge is that it may result in corrosion and weakening of the disc as it allows stagnation of line fluid in the disc. They are mostly applied in steam systems.
Split wedge or parallel disc valve: the split wedge or parallel disc valve is designed as two solid pieces joined by a particular device. This unique wedge can work when one half of the disc is out of alignment. The other hold disc can easily adjust to functioning as it were two based on the seating surface. The disc can be designed as parallel or wedge-shaped.

5. What do Gate Valves fail?

Gate valves are designed with a disc placed at the center of the valve. This disc moves as the valve handles are placed in an open position. As time sets in, the valve matures in terms of age and the disc tends to stick. When the valve is closed, fluid flow occurs because the disc has stuck while in an open position. The disc may remain in that position after opening the valve. When this happens, the gate valve has failed to carry out its main objective which is to block fluid flow when closed.

Another problem gate valves face is corrosion and wear. The gate valve is prone to wear often and when corrosion happens, it could cause sticking. A forceful turning of the valve handle will lead to breaking the stem and general valve damage.