Parts Of A Gate Valve
A gate valve is comprised of certain parts that allow it to function properly. The most principal part of this particular valve is the valve’s body or shell, which is considered the initial pressure boundary and can connect inlet and outlet pipes in a piping system. The shape of the body is often cylindrical and houses the gates, also known as the valve’s disks, and the valve’s seats.
There is a covering used for a valve body’s opening at the top and this is called the bonnet. A valve’s bonnet is often screwed in so as to enable any sort of maintenance or repair work to be done without having to remove the entire gate valve from the piping system, which would cause more headaches than necessary. The bonnet houses other internal parts of the valve such as the stem, gland packing, and gland follower.
The internal parts are known collectively as a valve’s trim and these are the parts that enable the valve to control the flow of water and other basic actions to be made. The first integral part of the trim is the disk, which has different kinds of designs as mentioned in the article entitled gate valve selection guide. The disk is what closes and opens, thus explaining why it is often referred to as the gate in this particular kind of valve. When the hand wheel or actuator is turned closed, the disk also seals up, preventing any water flow from occurring. When the hand wheel or actuator is turned open, the disk opens up, allowing water flow to happen.
The seat is thought of as the partner of the disk and can either be in a "V" shape or pointed valley for a wedge disk or in a parallel shape to that of a parallel disk. It is vital that both the disk and the seat are able to have a snug enough fit in order for it to be sealed, thus, making it impossible for any flow to occur when the valve has been closed.
The stem of the valve connects the hand wheel or actuator to the disk. The stem rotates as the hand wheel is turned, making it possible for the disk to rotate in the same motion as the stem and hand wheel. There are two kinds of stems: the rising stem and the non-rising stem. A rising stem rises above the hand wheel as the valve is opened while a non-rising stem does not.
The hand wheel is the circular part found at the very top of a gate valve. It is what controls the stem, which in turn controls the disk. It is turned clockwise to close the valve and counter-clockwise to open the valve.
The gland packing is composed of a material that creates a seal between the stem and the trim. The gland follower extends into the gland packing. It is necessary for the gland packing to be properly compressed to ensure no breach occurs.