6
avoid the seat retainer fall down from end
cap.
(5) To lift the ball by hoist, it must make the
protection on corner to avoid the ball
damaged by metal contacted.
e. Parts inspection, maintenance, and
replacement:
(1)Check the surface of ball if it is scraped
use the PT for inspection if necessary. If
there is any damage on the surface, then find
out the root cause such as the dirt fluid…etc.
avoid the damage factors as far as possible as
we can .
(2)The damage of the ball surface, to gauge if it
is locate on the contacting area of ball and ball
seat. If it is the case, then the ball must take
a fine milling. If it cause a heavy damaged,
then it must welded and re-machined. If it
cannot be repaired then change a new ball.
(3)If the scraped area is not at the location
described in the item (2)above, then it must
re-fine milling the damage area again.
Otherwise, the ball will damage the soft seat
during the open and close operation or it will
dig out the ball seat and cause a heavy
damage to ball and seat.
(4)Check the thickness of valve body and cap.
As defined in section 1. the body and cap
material may wear be cause of the status of
fluid.User should decide the frequency for
checking thickness.
(5)To inspect the surface of soft seat, if there is it
any scrap mark, concave, dust (including weld
dregs, iron bit, sands…etc.), abrasion,
abnormal press scrape, and a tiny scrap.
Usually, the scrape mark and damage by dust
will occur in the same time with ball damage.
It is the root cause for leakage. If the
leakage occurs before the repairing, then this
is suggest to change a new soft seat (PTFE or
RTFE). The mark from press or fine scrap
happen in an abnormal operation pressure.
It must be reconsidered to choice a right
valve.
(6) To check the worm gear if it can be operated
correctly, the operated correctly means people
can use one finger to turn the wheel. when
the torque higher then 25KG-M, if must open
the gear- box and check the connection of the
tooth of gear. To check has there is any
grease, spoiled grease, water, oxidation or
dust in the box.
(7) Worm gear operator has a switch of
open/close indicator get back to the original
location after dismantle or assembly. It must
do the pressure inspection before install onto
pipe line, otherwise, it will become very difficult
to do adjustment on the pipe line.The stem
packing must be replaced by new parts after
dismantle the valve. Its material has PTFE,
Graphite and Carbon Fiber. The material of
new packing must be the same as the old one.
To tight the gland nut, it must pass the 1.5
times water pressure test without leakage.
Do not make the gland nut too tight to avoid
the higher torque.
(8) To do the final inspection for a valve, 10
times of open and close operating must be
done to ensure all the parts are assembled
correctly. To ensure the torque is in a same
value during the open/close operation. If the
torque is not the same in operation, then there
may has some parts in an correct position or
interference.please dismantle and re-assembly.
Otherwise, the valve will get damaged easily
