by VALVE PARTS
Major parts common to most valves are as follows:
Body.
Valve Disc (Opening Element).
Stem.
Handwheel / Handle.
Bonnet.
Packing Gland
BODY
The body is the part of a valve that is attached to the pipework
flange. The gases or liquids flow through the body when the valve
is open.
VALVE DISC (OPENING ELEMENT)
This is the part that opens and closes the valve. All valves have
a valve disc in the valve body. Valve discs are made in various
shapes and sizes. They can move up and down with the stem, or rotate around a central pivot point.
The valve disc stops or allows flow through a valve. We will discuss
types of valve disc further when we look at different types of
common valves. When the valve is closed the valve disc fits against
the valve seat.
STEM
The stem raises or lowers the valve disc. In manually operated
valves the stem is usually threaded. In ball valves and butterfly
valves the stem does not move up or down. It turns inside the
bonnet. In pneumatic and hydraulic valves the stem is a smooth rod
that moves up and down in the valve body.
HANDWHEEL / HANDLE
On a manual valve a handwheel or handle is attached to the stem.
The handwheel or handle allows the operator to turn the stem.
The handwheel is held on the stem by a handwheel nut.
BONNET
The bonnet is a separate housing that is bolted tightly to the top
of the valve body. The stem passes through the bonnet.
The bonnet holds the stem in position.
PACKING GLAND
The packing gland is held in place by bolts or sometimes it is
screwed into place. This gland keeps the packing tight. Packing
is a soft material inside the bonnet placed around the stem to make
a tight seal. The packing stops pressurised gas or liquid in the
valve from escaping to the atmosphere.
Major parts common to most valves are as follows:
Body. Valve Disc (Opening Element). Stem. Handwheel / Handle. Bonnet. Packing GlandBODY
The body is the part of a valve that is attached to the pipework
flange. The gases or liquids flow through the body when the valve
is open.
VALVE DISC (OPENING ELEMENT)
This is the part that opens and closes the valve. All valves have
a valve disc in the valve body. Valve discs are made in various
shapes and sizes. They can move up and down with the stem, or rotate around a central pivot point.
The valve disc stops or allows flow through a valve. We will discuss
types of valve disc further when we look at different types of
common valves. When the valve is closed the valve disc fits against
the valve seat.
STEM
The stem raises or lowers the valve disc. In manually operated
valves the stem is usually threaded. In ball valves and butterfly
valves the stem does not move up or down. It turns inside the
bonnet. In pneumatic and hydraulic valves the stem is a smooth rod
that moves up and down in the valve body.
HANDWHEEL / HANDLE
On a manual valve a handwheel or handle is attached to the stem.
The handwheel or handle allows the operator to turn the stem.
The handwheel is held on the stem by a handwheel nut.
BONNET
The bonnet is a separate housing that is bolted tightly to the top
of the valve body. The stem passes through the bonnet.
The bonnet holds the stem in position.
PACKING GLAND
The packing gland is held in place by bolts or sometimes it is
screwed into place. This gland keeps the packing tight. Packing
is a soft material inside the bonnet placed around the stem to make
a tight seal. The packing stops pressurised gas or liquid in the
valve from escaping to the atmosphere.
