FIELD OF INVENTION :
The invention relates to means and measures for reducing crane capacity of a
large penstock valve house in a hydro electric project. More particularly the
invention relates to an off-set split penstock valve with horizontal trunions to
reduce the capacity of a valve house crane.
BACKGROUND OF THE INVENTION :
In a typical hydro electric plant, a penstock valve is installed upstream of the
main power house. The function of the penstock valve is to close the water
supply to the powerhouse incase of an emergency or for maintenance of the
powerhouse valve and turbine. One penstock valve generally caters to 2 to 3
turbines, and hence is very big in size.
From techno economic considerations it is generally aimed to reduce the size
and cost of the valve house in which is accommodate the penstock valve.
Some of the known means for reducing the cost of penstock valve house
are:-
1. Reducing the floor space required in the service bay.
2. Reducing the height of the valve house cavern.
3. Reducing the lifting capacity of the crane, which in turn not only
reduces the cost of the crane but also the crane movement
structure for example, the cost of crane columns, foundations of
the columns and the cost of beams.
The space required in the service bay normally depends on the factors for
example, whether the entire valve is to be assembled and turned after
assembly to be in its natural position in the service bay, or the service bay is
to be used only for unloading the valve door and body halves from a
transport trailer.
The height of the valve house cavern depends on configuration of the valve,
for example, whether the entire valve is to be assembled and turned to its
natural position in the service bay, or the configuration permits independent
handling of the valve body halves and the door.
The crane capacity depends upon the configuration of the valve for example,
whether the valve can be assembled part by part in-situ in its final position, or
the entire valve is to be assembled in the service by, lifted as a whole
assembly by the EOT crane, taken to its final position and installed on the
valve foundation.
As regards the state of art, large butterfly valve type penstock valves as
shown in figure 1 are known. The body of the valve is formed from transport
considerations for example, in two halves (1,2) splitted along a vertical plane
passing through the centre of the valve body. A hydraulic cylinder (4) for
opening/closing of the valve is mounted in a vertical plane of the valve floor,
and a closing weight for emergency closure (11) is mounted on a lever (5).
The two body halves (1) & (2) and a door (3) are transported to site
separately. The valve is assembled as shown in figures no.2 to 5. One half of
the body (1) is turned 90° from its natural position and kept on stools. The
door (3) along with its integral trunnions is lowered vertically into a trunnion
bush fitted in the body (1). Then the other half of body (2) is lowered over
the door (3) and the body halves (1,2) are bolted together and seal welded,
and the valve assembly comprising the body halves (1,2) and the door (3) is
turned by 90° to its normal position. This assembled valve is lifted by the
crane and taken to its position of final installation. The advantage of this
configuration of the valve is that the sealing between the body halves (1,2)
can be made by seal welding, which is highly reliable. The drawback of this
arrangement is that the valve house requires a crane of very high capacity,
viz:- that equal to the combined weight of valve body halves (1,2) and the
door (3) with trunions. This valve configuration also requires a substantial
floor space, and larger height in the service bay for assembly of the valve and
turning of the valve assembly to its natural positions.
Another prior art penstock valve is known and shown in figure 6. The body of
the valve in split into two pieces along a horizontal plane passing through the
centerline, however the trunion axis of the door is vertical. A lower part of the
body (6) comprises a plurality of legs for mounting on the valve foundation
and accommodates a first bush for the lower trunion. The upper half of valve
body (7) houses a second bush for the upper trunion of the door. A hydraulic
cylinder (13) for opening/closing of the valve is mounted horizontally on a
vertical load bearing member for example, a column or a load bearing wall.
Since the closing weight (10) for emergency closure serves no purpose if
mounted on the lever, the closing weight (10) is suspended from a wire rope
through a pulley bracket (12) mounted on the wall. The wire rope attached to
closing weight (10) is tied to a sheave sector type lever arm (9). This
configuration has the two advantages for example, a lower crane capacity,
and lesser space including smaller height required in the service bay, as no
assembly is to be done in the service bay. This configuration however has the
disadvantage for example, the difficulties in mounting the hydraulic cylinder
(13) and the pulley bracket (12) on vertical surfaces. The assembly of the
valve is carried out in-situ. The erection of the valve is simple as shown in
figure - 7.
Figure - 8 shows a still another type of prior art penstock valve in which the
body is split into two pieces along a horizontal plane passing through trunion
axis. As opposed to the known butterfly valve, the hydraulic cylinder (4) for
opening/closing of the valve is mounted in a vertical plane on the floor. The
closing weight (11) for emergency closure is mounted on the lever (5). The
valve assembly is carried out in-situ. The erection of the valve is simple as
shown in figure 9. In this configuration, joining the flanges of the body
halves, becomes very complicated for the following reasons :-
1. Seal welding of the joint cannot be done because of lack of welding
access after assembly of the door. Also the seal weld even if
possible cannot totally close the leakage path.
2. The rubber seal (cord) between the body halves has to be
additionally joined to a circular seal on the bush housing of the
trunion; which thus forms a T joint requiring substantial precision
while machining and erection, and the probabilities of achieving a
successful T' joint is not high.
The space left at the joint flange is too small to accommodate a
very rugged joining hardware and flanges to prevent a gap
formation on loading which would relax the compression of the T
joint. Thus, this known valve has the advantages of lesser crane
capacity, lesser floor space in service bay, and lesser valve house
height but has the drawback of complications of joining the flanges
including the associated leakage possibility.
OBJECTS OF THE INVENTION :
It is therefore an object of the invention to propose an off-set split
penstock valve with horizontal trunions to reduce the capacity of a
valve house crane.
Another object of the invention is to propose an off-set split
penstock valve with horizontal trunions to reduce the capacity of a
valve house crane, which reduces the floor space required in the
service bay including the height of the crane above the service bay.
A still another object of the invention is to propose an off-set split
penstock valve with horizontal trunions to reduce the capacity of a
valve house crane, which eliminates the problem of leakage
between the horizontal centre split valves and the horizontal
trunions.
Yet another object of the invention is to propose an off-set split
penstock valve with horizontal trunions to reduce the capacity of a
valve house crane, which reduces the transport length and weight
of the valve door.
A still further object of the invention is to propose an off-set split
penstock valve with horizontal trunions to reduce the capacity of a
valve house crane, which reduces the cost.
SUMMARY OF INVENTION :
Large penstock valves are split along the vertical centre line with the
operating hydraulic cylinders mounted on the floor. This known configuration
has the drawback, that it requires crane of a higher load capacity, to lift the
combined weight of the valve body and the trunion. The known Penstock
valve having the trunion axis vertical and the valve body split along a
horizontal plane passing through the centre line, has the advantage of lower
crane capacity which may be equal to the heavier one of the body halves, or
the door; however the known type valve has a major drawback that the
operating hydraulic cylinder has to be necessarily mounted horizontally with
its foundation on a vertical wall and involves wire ropes including pulley
brackets for the closing weight.
Penstock valve of yet another known type, has the trunion axis disposed
horizontally and the valve body is splitted also horizontally along a plane
passing through the centre line. This known configuration has the advantage
of lower crane capacity and normal mounting of the hydraulic cylinders in the
vertical plane but has the drawback, that joining of the body halves becomes
very complicated both from the point of view of providing bolting of required
strength due to limitation of space. Further, the sealing of the body halves
with that of the trunion bush demands a workmanship of high precision.
To overcome drawback of the prior art penstock valves, the present invention
provides a valve having a body split into two halves which are offset from the
trunion axis. The inventive valve not only reduces the crane capacity but also
simplifies the process of body joint from the bolting and sealing
considerations. Also the door with bolted trunions of the valve reduces the
transport constraints. This novel and inventive valve requires machine tool of
smaller sizes to machine the door. The trunions are machined independently
on smaller machines. Since the door does not have trunions, the machine tool
(vertical borer) required to machine the door is much smaller.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure -1 - Shows a large butterfly type penstock valve of prior art with
horizontal trunion and vertical body.
Figure- 2 - Schematically shows the first stage of erection of valve of
Figure-1.
Figure-3 - Shows the second stage of erection of valve of Figure 1.
Figure-4 - Shows the third stage of erection of valve of Figure 1.
Figure-5 - Shows the fourth stage of erection of valve of Figure 1.
Figure-6 - Shows a prior art penstock valve with vertical trunions and
horizontal flange joint.
Figure-7 - Shows the in-situ erection sequence of valve of Figure 6.

Figure-8 - Shows another type of prior art penstock valve with horizontal
trunions and horizontal flange joint passing through trunions.
Figure-9 - Shows the erection sequence of valve figure 8.
Figure-10 - Shows an off-set split penstock valve with horizontal trunions
according to the invention.
Figure-11 - Shows the first and second erection stages of the off-set split
valve of figure -10.
Figure-12 - Shows the third erection stage of the off-set split valve of
figure-10.
Figure-13 - Shows the fourth erection stage of the off-set split valve of
figure-10.
Figure-14 - Shows the details of bolting of trunion flange and door of the
off-set valve of figure 10.
Figure-15 - Shows a comparison of size of the machine tool required for
machining of the valve doors of valves of figures 1, 6 and 8 with
that of valve of figure - 10.
LIST OF ITEMS
1. Right half body of the valve (Figure 1)
2. Left half body of the valve (Figure 1)
3. Door of the valve (Figure 1)
4. Hydraulic Cylinder of the valve (Figure 1)

5. Lever of the valve (Figure 1)
6. Lower half of the Valve body of Valve (Figure 6)
7. Upper half of the Valve body of valve (Figure 6)
8. Door of the Valve (Figure 6)
9. Sheave sector type Lever of the valve (Figure 6)
10. Closing weight of the valve (Figure - 6)
11. Closing weight of the valve (Figure - 1)
12. Pulley block of the valve (Figure - 6)
13. Hydraulic Cylinder of the valve (Figure-6)
14. Lower body of the valve (Figure - 8)
15. Upper body the valve (Figure - 8)
16. Lower bigger body of the valve (Figure-10)
17. Upper smaller body of the valve (Figure-10)
18. Door without trunions of the valve (Figure-10)
19.Trunions with rectangular flanges of the valve (Figure-10)
20.Trunion insert block of the valve (Figure - 10)
21. Location Dowel (Figure - 10)
22. Torque Dowels (Figure - 10)
23. Shear bushes between the Door and the Trunion flange (Figure-10)
24. Shear bush between the upper and lower body of the valve (Figure-13)
25. Alignment screw (Figure 10)
26. Bolts joining the door to the trunion (Figure-14)
DETAIL DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION.
As shown in figure 10, the off-set split valve of the invention has a flange
joint joining the body parts (16, 17) in a horizontal plane off-set from the
trunion axis so that the bush for the trunions (19) is housed in the lower body
(16), instead of falling half in lower body part (16) and the rest in the upper
body part (17). The upper part of the valve body (17) is relatively smaller.
The joint flange is so much off - set from the trunion axis, that it not only
permits comfortable accommodation of the valve bush but also permits a
good seal welding of the joint.
The door (18) is not formed in a single piece but split into three viz. the left
and right trunions (19) with flanges and the main disc of the door (18).
The trunions (19) have a cylindrical journal portion with a hammer head like
rectangular flange, to be bolted and dowelled to the door. The door (18) has
rectangular machined flanges at either end for bolting with rectangular
flanges of trunions. The trunions and the door flanges have bores into which
fits a trunion block (20) designed to transfer the bending load of the door to
the trunion (19). This trunion block (20) also serves to align the trunions (19)
and the door (18) along the rotational axis.
The rectangular flanges of the trunions (19) and the door (18) are bolted
using hollow type first shear bushes (23) which apart from the transferring
torque help in arresting opening out tendency of the flange joint. For torque
transfer, a plurality of cylindrical dowels (21) located in two halves between
the trunion flange (19) and the door (18), are used at distances far away
from the trunion axis. For ease of erections, at least one cylindrical location
dowel (21) on each end of the door (18) is used between the trunion flange
(19) and the door (18). This helps in correctly locating the door (18) while
being lowered on to the trunions (19) for assembly.
These locating dowels (21) locate the door (18) with respect to the trunions
(19) in one plane. For locating the door (18) with respect to the trunions (19)
in the perpendicular plane, at least two number alignment/jacking screws
(25) are used. These screws (25) are used to correctly align the matching
bores in the door (18) and the trunion (19) for the trunion block (20).
The two parts of the valve body (16, 17) are joined using a plurality of second
shear bushes (24) which not only align the two parts of the valve body but
also arrests the opening tending at the flange joint.
WE CLAIM :
1. An off-set split Penstock valve with horizontal trunions to reduce
crane capacity, comprising :
a lower half part (16) of a valve body accommodating a plurality of
bushes for multiple trunions (19);
a plurality of mounting feet for fixing the valve on the valve
foundation, including joint flange for bolting with an upper part
(17);
at least two trunions (19) with rectangular flanges for bolting with a
valve door (18);
a trunion block, (20) partly insertable into the trunion (19) and
partly into the valve door (18) for transferring a forward bending
load of the door (18) to the trunion (19);
a plurality of torque dowels (22) insertable between the trunion
flange (19) and the door (18);
at least one location dowel (21) to locate the door (18) while being
lowered on to the trunion flange (19);
a plurality of alignment screws (25) for bringing the door (16) in a
relative level corresponding to that of the trunion flange for
alignment of the holes in trunion block (20) and the matching bores
in the door (18);
a plurality of first initial shear bushes (23) for joining the trunion
flange (19) and the door (18);
a plurality of bolts (26) for tightly fixing the trunion flange and the
door (18) after the initial joining;
a plurality of second shear bushes (24) for aligning the upper and
lower body parts (16, 17) and arresting and deflection at the joint
between the trunion flange (19) and the door (16);
wherein the upper part of the body (17) being smaller in size in
respect of the lower part (16), and having only joint flanges without
any part of the housing for the trunion bush (23) forming the upper
part (17).
2. An off-set split Penstock valve with horizontal trunions to reduce
crane capacity, as substantially described and illustrated herein with
reference to the accompanying drawings.

The present invention provides a valve having a body split into two halves
which are offset from the trunion axis. The inventive valve not only reduces
the crane capacity but also simplifies the process of body joint from the
bolting and sealing considerations. Also the door with bolted trunions of the
valve reduces the transport constraints. This novel and inventive valve
requires machine tool of smaller sizes to machine the door. The trunions are
machined independently on smaller machines. Since the door does not have
trunions, the machine tool (vertical borer) required to machine the door is
much smaller.