Design & Construction

Stem design

Anti-Static Device

The anti-static feature is achieved

through metal-to-metal contact of the

stem to the stem neck by means of

the ball and spring built into the stem

of the valve.

Anti-Blowout

The stem is designed to be

blowout proof by means of a specially

designed stem shoulder and thrust

ring.

Ball Construction
The ball, which is the most critical part of the ball
valve, determines both the quality and service life
of the valve. It must therefore be precise.

We will help in the selection of either a floating
ball or a Trunnion mounted ball depending on
size requirement and specification. The different
ball types include solid ball, cavity ball and hollow
(concave) ball.

Double Block & Bleed with Body Drain

When the valve is fully closed, the specially
designed drain valve can be opened to drain the
contents in the valve cavity. This can be done
while the valve is still in service and under
pressure.

Sealing Construction

Multiple O-rings are used to create the stem seal
while graphite and PTFE are added to further
enhance the fire safety design.
The ball rotates around its fixed vertical axis
between the stem and the trunnion at the bottom.
Positive sealing is accomplished by pressing the
seat ring (Viton/PTFE/ Nylon, etc) onto the
precisely rounded ball surface. Pressure from the
seat ring is provided by high tensile coil springs
which readily adjust to the constantly changing
line pressure.

Seat Design Features
The valve seat used in sizes smaller than 4” is a plastic polymer
material which is highly resistant to abrasion and corrosion, and
it exhibits self-lubricating properties that reduce friction thus
minimizing torque requirements. The emergency sealant fitting is
for the stem only.
The dual sealing mechanism is designed with metal-to-metal
seats as the primary seal and a secondary seal consisting of
protected synthetic O-rings.

Fire safety
In order to minimize leakage in the event of fire, KMC has
designed and tested valves for Fire Safety in accordance with BS
6755-2, API 6fa, and API STD 607.

Sealant & Lubrication System

Generally, valves 4” and larger can be fitted with an
emergency seat sealant system. The lubricant and
sealant fittings are located on the valves end pieces
and on the stem neck. The lubricants and sealants
are injected into the sealant channels and the seal
face passages.
Lubricants help to lower the operating torque of the
valve, while the sealants seal minor scratches
abrasions on both the seal faces and/or ball. The
purpose of sealants is to provide for temporary shut-
off in emergency situations. Before attempting to seal
such minor leaks, consult the valve manufacturer or
sealant experts.