Process Operation Technology

I invite you to join Process Operation Technology website

You can find everything about industry area
Your Engineering Reference
Your Guide in your Career

You can find new news about Process Operation Technology
You can find all famous magazines
You can find all New updated programs

With Operation Technology website, You're on the right way
Process Operation Technology

Oil, gas and petrochemical process industries


    Talib Al_Munawri

    Posts : 337
    Join date : 2009-07-03
    Age : 30
    Location : Sultanate of Oman


    Post by Talib Al_Munawri on Thu Sep 17, 2009 9:16 pm


    Major parts common to most valves are as follows:

    Arrow Body.
    Arrow Valve Disc (Opening Element).
    Arrow Stem.
    Arrow Handwheel / Handle.
    Arrow Bonnet.
    Arrow Packing Gland


    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.


    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.


    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.


    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.


    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.


    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.

      Current date/time is Fri Jan 19, 2018 8:25 am