GATE VALVES

GATE VALVES FUNCTION:

Gate valves are isolation valves, where a gate is lifted from the flow path and then returns to its original position. Gate valves provide a straight through unobstructed passageway, resulting in a minimal amount of pressure loss. Also, this unobstructed bore of gate valve allows for pig passage during pipe cleaning

The gate valves operator:  Hand wheel / Actuators (Electric, Pneumatic or Hydraulic.)

APPLICATIONS

Industries such as oil and gas, pharmaceuticals, manufacturing, automotive, and marine

In high temperature and high pressure environments: Power plants, water treatment plants, mining, and offshore applications.

GATE VALVES CLASSIFIED IN THREE CLASSIFICATIONS:

1- Parallel / Wedge-shaped Gate Valves

Parallel gate valves are linear, quarter-turn that regulates liquid flow. When opened, they completely block off the fluid path, flow resistance is higher. Recommended in less dense liquids.

Wedge-shaped Gate Valve flow resistance is lower, so it is suitable for quickly shutting off liquids. Recommended in high viscous fluids.

2-Metal Seated / Resilient Seated Gate Valves

Metal Seated Valve is generally made of metal, so it is also called metal sealing surface. The metal sealing surface is susceptible to deformation due to the influence of the medium and the sandwiched particles; it is further damaged by corrosion, erosion and wear. On the contrary, if the wear particles are less uneven than the surface, the accuracy of the relatively rough surface will be improved when the sealing surface is running in.

Resilient Seated Valve has two contacting sealing surfaces can be separate or all soft materials such as plastic and rubber can be used. Since the soft material is easy to deform and fills up the unevenness of the sealing surface, the soft seal can achieve a very high degree of medium sealing performance, and this extremely high degree of medium sealing performance can be repeatedly achieved.

3-Rising OS&Y / Non-Rising Stem Designed Gate Valves

Rising stem-designed gate valves have stems outside the valve body and move with the gate. As the gate moves upward, so does the stem and vice versa. This movement allows the stem to be monitored for maintenance. This design is best used for surface installations.

Non-rising stem designs gate valves the stem rotates with the gate movement from inside the valve body. An indicator on top of the stem shows the position of the valve. This design can be used in industrial gate valves for surface and underground installations.

INSTALLATION OF GATE VALVES

Installing gate valves should be done properly to increase the service life of the gate valves and to ensure their proper operation. Here are some installation practices to be followed while installing gate valves:

• Installation of the gate valve, the flange must be at room temperature.
• While valves can be installed in any form, flat or upright, it is advisable to install them in an upright form for easy hand-wheel access.
• Ensure that during installation, the pipe flanges are spaced so that there is enough space for the valve to be inserted or removed during servicing.
• Welding jobs should be completed before the installation of the gate valve.
• Sludges and waste residues in the pipeline must be washed away before the valves are installed.
• The flange and valve should be properly aligned, and the pipe handling of the weight of the valve should be checked.
• The materials of the gate valve parts should be checked to ensure no damage was done during transportation or storage.
• The bolts connecting the valve to the pipes should be tightened properly, and the pressure should be equally distributed.
• The parts of the pipe flanges to contact the valves should be clean and free of residue.
• The gate valve should be tested after bolting to ensure the valve is stable in its position.

MAINTENANCE OF GATE VALVES

 Below are some essential practices to ensure the valve works effectively and lasts longer.

• The pressure in the pipes should be released before maintenance of the gate valves commence.
• The pressure in the pipes or valves should be released before commencing maintenance.
• The gate valve disc should be replaced from the top by removing the bonnet and the stem before the disc is replaced.
• The valve should be cycled regularly when not in use.
• The process of removing the valve should occur in reverse of the installation.