FIELD OF THE INVENTION
The present invention relates to an improved testing device to perform a
hydrostatic test on the cast body in particular cast door of butterfly valves to
determine the quality requirement before machining and assembly of the valve.
The invention further relates to a process of hydrostatic testing of cast valve
body and valve door of an un-assembled butterfly valve.
BACKGROUND OF THE INVENTION
Butterfly valve is disc type valve which is normally used to control flow of large
mass of fluid flowing through the channel/pipe. Butterfly (BF) valves are installed
to provide a leak tight joint to prevent flow of fluid in connecting
equipment/service line. Fluid can pass only when the valve is operated i.e. valve
is opened. These valves are operated when required and in some cases, the
frequency of operation is also very high. Hence, design and manufacturing of
Butterfly valves warrant provision of a leak tight joint. Leak tightness in butterfly
valve depends upon the geometry of the seating arrangement provided between
the BF valve body and the operating Door.
Hydrostatic testing is performed to verify the leak tightness and strength of the
Butterfly valve components, specially, Body and the Door. In general, hydrostatic
testing is carried out after final assembly of the valves before final dispatch. Any
leakage from the cast body and door, if observed at this stage, leads to rejection
of the complete assembly due to functional failure and casting defects observed
at this stage only.

According to prior art, hydrostatic testing of a complete assembly of butterfly
valve and Valve body is performed. However, testing of Butterfly Valve Door
separately requires special arrangements. In the prior art, pressure testing of a
butterfly valve Door is carried-out by installing a specifically fabricated and fully
machined valve seat fixed by a set of grub screw on the testing location.
As shown in figure 1, the testing arrangement requires precise control on the
process i.e. marking, matching, alignment etc. This process consumes significant
amount of time during the assembly and testing of door joint.
As the complete arrangement i.e. machining, positioning of seat including its
alignment, are done for a specific door getting fitted in that valve, this limits the
interchangeability. Further, during operation also, this locking arrangement may
get loosened due to flow induced vibrations and thus, the leak tightness of the
seat gets disturbed. This results in un-desirable leakage of fluid through the
butterfly valve.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose an improved testing device
to perform a hydrostatic test on the cast body in particular cast door of butterfly
valves to determine the quality requirement before final machining and assembly
of the valve.
A further object of the invention is to propose a process of hydrostatic testing of
cast valve body and valve door of an un-assembled butterfly valve.

SUMMARY OF THE INVENTION
Accordingly, there is provided an improved testing device to perform a
hydrostatic test on the cast body in particular cast door of butterfly valves to
determine the quality requirement before final machining and assembly of the
valve, the device comprising:
a ring shaped seat extension/projection casted as an integral part of the valve
body; a door seating means with profile machined to match that with the
integrally cast seat extension, wherein the valve body is provided with said
corresponding matching profile to produce a fail safe seating means.
In a second aspect of the invention, there is provided a process of hydrostatic
testing of cast valve body and valve door of an un-assembled butterfly valve.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 - Shows a sectional details including photographic view of a prior art
device for testing of completely assembled butterfly valve.
Figure 2 - Shows a sectional details including photographic view of an improved
device for performing hydrostatic test on cast valve body and valve door before
the final assembly of butterfly, valves according to the invention.
Figure 3 - Shows a schematic view of hydrostatic testing sequence of valve body
and valve door integrated with seat profile and seal profile according to the
invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
Hydrostatic testing of a valve body is easy to perform, however, to carry out the
hydrostatic testing of a valve door, a valve body is modified for its seating
surface by making it as an integral part of the body (refer Figure no.2) instead of
having a separate seat assembly according to prior art (refer figure 1). This
single modified valve body is used for performing hydrostatic test for several
matching doors. A single set of remaining assembly items, which may be of
alternate material, is also used for testing purpose. The modified body can then
be finally machined as per figure 1 for hydraulic including functional testing of a
fully assembled butterfly valve according to known testing procedure.
For hydraulic testing of the body, flanged ends at upstream and downstream
side of the body are blanked with a test cone and openings for the trunnion
housing are covered with blank flanges.
For hydraulic testing of a finished door, a valve body of each size is modified to
house a door under testing. The bores of the trunnion on the valve body housing
kept same as that of the trunnion on the valve doors. In the valve seat area of
the valve body, additional material is provided for making an integral valve seat
on the valve body. The valve body is then fully machined except for above
mentioned two changes.

Further, in the door, a rubber seal is assembled with a clamping ring. The door is
then assembled with the modified valve body and the trunnions are inserted in
the door including body housing. The bores of the trunnion housing are closed
with blank flanges. The open end of the body is blanked with a test cone and
hydraulic test of the door is carried out.
After completion of the hydraulic test of the door of the BF valve, this modified
body is further machined to make the bores in trunnion housings as per
assembly drawing, and the bore in the valve seat area is machined as per
drawing.
After removal of the added features, this body is hydraulically tested for
soundness and supplied as a regular valve body.
The test device for the valve door is shown at figure 3.

WE CLAIM :
1. An improved testing device to perform a hydrostatic test on the cast body
in particular cast door of butterfly valves to determine the quality
requirement before machining and assembly of the valve, the device
comprising :
a ring shaped seat extension/projection casted as an integral part of the
valve body; a door seating means resting seat with a special profile
machined out of the integrally cast seat extension in the body whereas
the door is provided with door seal to produce a fail safe seating means.
2. A process of hydrostatic testing of cast valve body and valve door of an
un-assembled butterfly valve, the process comprising the steps of :
providing additional built-up materials at the seating surface of the cast
valve body to produce a modified valve body with integral seat;
closing the flanged ends of the valve body with a test cone and covering
the openings for the trunnion housing with blank flanges;
performing a hydrostatic testing of the valve body;
modifying the valve body to house a valve door under testing, the bores
of the trunnion on the housing of valve body and valve door being
maintained with identical size;
fixing a rubber seal on the valve door using a clamping ring of alternate
material prior to final assembly;

- assembling the valve door with the modified valve body through inserting
the trunnion via the identical bores, the bores of the trunnion housing
being closed by blank flanges wherein the open end of the valve body
blanked with a test cone; and
- conducting the hydrostatic testing of the valve door before final assembly.

ABSTRACT

The invention relates to a process of hydrostatic testing of cast valve body
and valve door of an un-assembled butterfly valve, the process comprising
the steps of : providing additional built-up materials at the seating surface
of the cast valve body to produce a modified valve body with integral
seat; closing the flanged ends of the valve body with a test cone and
covering the openings for the trunnion housing with blank flanges;
performing a hydrostatic testing of the valve body; modifying the valve
body to house a valve door under testing, the bores of the trunnion on
the housing of valve body and valve door being maintained with identical
size; fixing a rubber seal on the valve door using a clamping ring;
assembling the valve door with the modified valve body through inserting
the trunnion via the identical bores, the bores of the trunnion housing
being closed by blank flanges wherein the open end of the valve body
blanked with a test cone; and conducting the hydrostatic testing of the
valve door.