Claims:1. A top entry push type trunnion mounted ball valve having atleast a valve body,a ball and two seat rings arranged at either side.Said two seat rings are pushed away from each other inside the valve body to create space for entry of ball and thereafter seat rings to be withdrawn towards the ball, the said seat ring assembly comprising of :
a. a hook body,
b. a latch body,
c. a spring means and
d. a latch means
Characterized in the hook and latch mechanism arrangement and the said arrangement made within the valve body.
2. A top entry push type trunnion mounted ball valve as claimed in claim 1, wherein the valve body is the hook body to form an integral latch mechanism.
3. A top entry push type trunnion mounted ball valve as claimed in claim 1, wherein the valve body is not hook body to form an isolated latch mechanism.
4. The top entry push type trunnion mounted ball valve as claimed in claim 1 & 2 comprises of:
a. a hook body (1b) which is the valve body (1b) having plurality of hook groves,
b. a latch body comprising of seat ring (2b) with annular grooves correspondingly matching into the hook grooves to form a plurality of closed slots and said seat ring also having a plurality of holes,
c. a plurality of springs (3b) accommodating into said holes of latch body and said springs adapted to energise the seat ring (2b) towards the hook body, and
d. a latch (4b) which is plurality of removable segmented retainer rings adapted to be insertable into the said formed plurality of closed slots with annular grooves of seat ring (2b) and hook grooves in hook body (1b), thereby adaptable to locking the pushed seat ring with the hook body against the spring force.
the said arrangement characterized in the hook and latch mechanism operation and wherein the valve body (1b) itself is the hook body (1b) and further with the latch body (2b) and latch (4b) all arranged within said valve body (1b), thereby forming an integral latch mechanism.
5. The top entry push type trunnion mounted ball valve as claimed in claim 1 & 3 comprises of :-
a. a valve body (1a),
b. a hook body (5) is ring shaped having a plurality of rectangular extending hooks (6), the said hooks having plurality of slots and the said hook body also having a plurality of holes,
c. a latch body is ring shaped having seat ring (2a) with slots on its head, the said slots matching correspondingly to accommodate the said rectangularly extending hooks,
d. a plurality of springs (3a) accommodating into said holes on the hook body that said springs adapted to energise the seat ring (2a) towards the hook body, and
e. a latch (4a) which is a retainer ring with slots, rotatably moveable over the hook body along the slots of hooks thereby adaptable to locking the pushed seat ring with the hook body against the spring force,
the said arrangement characterized in the hook and latch mechanism operation and in the said latch body (2a), hook body (5) and latch (4a) all arranged within the said valve body (1a), thereby forming an isolated latch mechanism
, Description:FIELD OF INVENTION

The invention relates to Top Entry Trunnion Mounted Ball Valves and maintenance of same.

DESCRIPTION OF THE PRIOR ART

The current invention related to Top Entry Trunnion Mounted Ball Valves (TETMBV) mainly used as on-off valves in pipe lines. These are position seated quarter turn ball valves.

Typical Top Entry Trunnion Mounted Ball Valves consist of a ball and two seat rings at either side which are spring energized. Ball is supported by body through trunnions on either ends of ball perpendicular to flow axis.

In TETMBV (Refer Fig-1), there will be an integral body with two end flanges / butt weld ends. There will be an opening whose axis will be perpendicular to the flow bore axis, located at the top of the body for assembly and disassembly of ball and other internal parts. Then a cover bolted over it.

Valve will be installed in the pipeline either using end flanges bolted to pipe flanges or butt weld ends welded with pipeline. The top opening in the valve helps to perform online maintenance (service or replacement of parts) without uninstalling the valve from pipeline.

The two seat rings need to be pushed away from each other inside the valve body in order to create adequate space for the entry of the ball and then the seat rings to be withdrawn towards ball. Seat ring thrust on the ball is achieved using adequate spring load.

There are different types of assembly constructions currently being employed by different valve manufacturers.

• Push type:
o The gap between 2 seat rings when spring is uncompressed will not be adequate to insert the ball.

o The seat ring has to be pushed against spring force to insert the ball

Push type design is the most simplest of all the designs except for the arrangement to hold the seat ring in place which makes it complicated.

In Push type, the seat ring is pushed in to the body by compressing spring using special hydraulic fixture & holding the seat ring help in that position by mechanical means and then ball is inserted. Then fixture is released for seat ring to engage with ball with required spring load.

• Pull type
o The gap between 2 seat rings is kept sufficient enough to insert the ball when the spring is uncompressed.
o Later the seat ring has to be pulled towards the ball compressing the spring to required level & lock the position using Circlip/Retainer ring.

In pull type arrangement, the seat ring will be pushed into the body & ball inserted. Then the seat ring will be pulled out of body by compressing spring using either hydraulic cylinder or a screw jack and then a Circlip/Retainer ring is inserted in that position to ensure required spring load.

• Threaded type

o Each seat ring will be of two parts which are screwed into each other by threads to alter the overall length.
o The gap between two seat rings is kept sufficient enough to insert the ball when the spring is uncompressed.
o Two parts will be unscrewed to advance the seat rings towards the ball as well as to compress the springs to required level.

In threaded type, seat ring is externally threaded and spring holder spring is internally threaded, which moves over the seat ring and springs are located inside the spring holder. The whole arrangement is pushed into the body. Then the ball is inserted into the body & then spring holder is rotated to pull the seat ring from body & towards the ball & till required spring compression is achieved by maintaining the specified gap between seat ring and spring holder.

DISADVANTAGE OF THE PRIOR ART:

In existing “Push type” design, different methods are used to push & hold the seat ring in position. One of the methods is to puncher the valve from outside & put separate conical plugs that will push the seat ring back & release it. Refer Fig-2.

The main disadvantage of this system is that the body requires additional holes, additional sealing system that is not recommended by many customers & specifications restricts it. Main disadvantage of this method is the thread in the body will get loaded & if the thread gets worn out or damaged then it will become impossible to remove the ball out. There can be possibility of leakage from these tapped holes when valve is under operation. There can be possibility of rust formation & plug getting stuck in case of carbon steel bodies.

In “Pull type” design as shown in Fig-3, there will be no threaded holes required on the body for the purpose of moving the seat ring. But this requires some arrangement to pull both the seat rings towards the ball, either a screw jack or a hydraulic cylinder. In either case it requires some hooking arrangement on the seat ring and has to be aligned with opposite seat ring otherwise pulling will become impossible.

There is a Circlip/Retainer arrangement to lock the seat ring in position. Assembling the Circlip/Retainer is difficult & tedious when seat ring is in pulled condition, as there is no accessibility around the seat ring. If the Circlip/Retainer fails, it will directly affect the valve performance, since required spring load is lost.

In “Threaded type” design as shown in Fig-4, the spring holder is threaded to the seat ring the spring compression is maintained by the position of spring holder after assembly. If the thread slips while the valve is in operation then the spring load will change & will affect the valve performance. As the thread is used to position the spring holder & no locking occurs, there is always a chance of spring holder moving from its position.

The assembly is very tedious as the spring holder has to be rotated & the rotation is achieved by multiple small strokes due to inadequate space for the tool approach. When the valve is in service for long time there is chance of thread getting stuck due to line contamination & unscrewing of the spring holder may be due to vibration in the pipeline, may affect valve performance or become tedious to carryout online maintenance.

OBJECT OF THE INVENTION

The object of the invention is to provide a Top entry Trunnion mounted ball valve which overcomes all the sufferings of the prior art.

In accordance with the present, the object has been achieved by the Top entry Trunnion mounted ball valve-Latch lock type as disclosed herein and claimed herein.

BRIEF DETAILS OF DRAWINGS

Fig.1 - Typical Top Entry TMBV construction as per API-6D.
Fig.2 - Push Type with Conical Plug
Fig.3 - Pull Type with a Circlip
Fig.4 - Threaded Type construction
Fig.5 - Hook & Latch Mechanism
Fig.6a,6b - Integral latch design.
Fig.7a,7b - Isolated latch design
Fig.8a,8b - Exploded perspective view of a Top entry Trunnion mounted ball
valves according to the present invention – Integral latch design
Fig.9a,9b - Exploded perspective view of a Top entry Trunnion mounted ball
valve according to the present invention – Isolated latch design.
Fig.10a,10b - Cross section of valve body of isolated latch design.
Fig.11a, - Seat Ring assembly – integral latch design
Fig.11b - Seat Ring assembly – isolated latch design
Fig.12a - Seat Ring sub-assemblies in the seat bore of valve body – integral
latch design
Fig.12b - Seat Ring sub-assemblies in the seat bore of valve body – isolated
latch design
Fig.13 - Motion of seat rings for assembling the ball into body
Fig.14a - Arrangement of seat rings at extreme ends – Integral latch design.
Fig.14b - Arrangement of seat rings at extreme ends – Isolated latch design.
Fig.15 - Arrangement of latching for locking in integral latch design
(Stage-1 & 2)
Fig.16 - Arrangement of latching for locking in isolated latch design
(Stages 1 to 5)
Fig.17 - Ball in open position with retracted seat ring for inserting ball into
the body
Fig.18 - Ball in closed position for disengaging the latch

Figure No. Part No. Component Name
1 7
8
9
10
11
12
13
14 Stem Seal
Bonnet
Bonnet cover
Body bolting
Body
Seat ring
Stem
Ball
2 15
16
17
18 Seat ring
Ball
Body
Conical Plug
3 19
20
21
22 Body
Seat Ring
Ball
Circlip / Retainer
4 23
24
25
26 Body
Seat Ring
Ball
Spring Holder
5 27
28
29
30 Hook body
Latch
Latch Body
Hook
6a

6b 31
32
33
34 Spring Holder
Valve Body
Seat Ring
Seat ring to be locked with spring holder
7a

7b 35
36
37 Valve body
Seat ring
Seat ring to be locked with valve body
8a,8b 1a
2a
3a
4a
5
6 Body
Seat ring (latch body)
Spring
Retainer ring (Latch)
Hook body
Hook
9a, 9b 1b
2b
3b
4b Valve Body
Seat ring (latch body)
Spring
Retainer segment (Latch)
10a, 10b 38 Integral Hook
11a
11b Integral seat ring assembly
Isolated seat ring assembly
12a
12b Integral seat ring assembly-inside valve body
Isolated seat ring assembly-inside valve body
13 Motion of seat rings for assembling the ball into body
14a

14b Integral arrangement of seat rings at extreme end
Isolated arrangement of seat rings at extreme end
15 (Stages 1 & 2) Arrangement of latching for locking in integral latch design
16 (Stages 1 to 5) Arrangement of latching for locking in isolated latch design
17 39 Ball in open position
18 40
41 Space for pushing aid
Ball in closed position

DESCRIPTION OF THE INVENTION

The invention works on the principle of hook & latch mechanism. Hook & latch is a shear locking mechanism to hold 2 members in a defined position. Hook body & Latch body are two entities that have to be locked in a particular position. Either of this body or both will carry the required load.

Either Hook body or Latch body is movable individually or both together. The load carrying body when locked will transfer the complete load to the fixed body.

Latch is a sliding member, sliding into the hook, thereby locking both bodies together. Refer the Fig-5.

This Hook-Latch arrangement concept is applied in a push type assembly trunnion mounted ball valve. The combination of hook-latch arrangement & push type assembly in top entry design gives the advantage over all other type of seat ring locking & assembly type.

This invention focuses on applying Hook-latch arrangement along with Push type assembly for assembly, disassembly & servicing Top entry TMBV when valve is installed in pipeline without dismantling the valve out of pipeline.
Based on the locking method which is done after the seat rings are pushed, there are two type of configurations used in this design. One is “Integral latch” and another one is “Isolated latch”.

Integral latch design:
In this design, both latch body & hook body are part of seat ring subassembly. Seat ring is acts as latch body and the spring holder acts as hook body. Complete arrangement is integrated in seat ring. The valve body doesn’t form part of this mechanism as mentioned in Fig-6.

Isolated latch design:
In this design, portion of arrangement is in the valve body & the other portion in the seat ring. Hook & hook body is the part of valve body, Latch & latch body is part of seat ring. This requires a specially designed valve body with portion of mechanism incorporated.
Latch is a separate loose piece (which is used only while valve assembly / disassembly to lock the seat ring and it will be removed to release the seat ring). Two latches are used for a seat ring.

Construction:
Integral latch design
As shown in figure-8, the new system consists of
1a - Body
2a – Seat ring (Latch body)
3a - spring
4a – Retainer ring (Latch)
5 – Hook body
6 - Hook

Valve body (1a):
As shown in Fig-8, the valve body is an outer casing which has provisions to accommodate all the other components. Body (1a) shown in Fig-8 is quarter sectioned and it is symmetry about the cross hatched planes

Seat ring (2a):
Each seat ring has two or three through slots provided on its head as shown in Fig-8. These slots accommodate the hooks (6) which are fastened to the hook body (5).

Spring (3a):
Spring (3a) is used in the system to energize seat ring (2a) towards the ball during the low pressure sealing which exists in the existing system as well.

Retainer ring (4a):
Retainer ring is a ring with three slots on its circumference as shown. This retainer ring acts as latch in valve assembly. After pushing the seat ring (2a) completely, the retainer ring can be rotated over the slots of the hooks (6) to lock the seat ring along with the hook body (5) against the spring force.

Hook body (5):
Hook body is a ring provided with drill holes to accommodate the springs (3a). Hooks (6) are fastened to the hook body using cap screws. Hook body slides on the seat ring (2a) OD thus engaging the hooks (6) into the seat ring (2a) slots.

Hook (6):
Hook is a rectangular blocks which has a slot across its length. The hooks are fastened in the hook body (5). the function of the hooks are explained before.

Isolated latch design
As shown in figure-9, isolated design consists of

1b – Valve body
2b - Seat ring (Latch body)
3b – Spring
4b – Retainer segment (Latch)

Valve body (1b):
As shown in figure-10, the valve body is an outer casing which has provisions to accommodate all the other components. Body (1b) shown in figure-9 is quarter sectioned and it is symmetry about the cross hatched planes As shown in figure-9 & 10, the valve body has 4 hooks (explained in working principle) is cast integral with body & grooves machined to required dimension.

Seat ring (2b):
Seat ring functions latch body as explained in working principle. Seat ring has an annular groove. Seat ring has holes to accommodate the springs (3b). Seat ring can be pushed into the valve body (1b) using a pushing aid. By pushing the seat ring, the annular groove in the seat ring matches the hook groove in the body (1b) creating a closed slot for entering retainer segment (4b) which is latch. This latch keeps seat ring (2b) not coming out of the body due to the spring force.

Spring (3b):
Spring is used in the system to energize seat ring (1) towards the ball during the low pressure sealing which exists in the existing system as well.

Retainer segment (4b):
It is a segment ring shaped component which is inserted in a closed slot which is formed by seat ring (2b) and hook groove in the body (1b). Two retainer segments are used to latch the each seat ring. These retainer segments carry the shear load generated by the springs (3b) which are in compressed position.

ASSEMBLY
Assembly of both type Integral and Isolated latch designs are done in same manner which are explained in parallel below. Figure numbers followed by “a” will indicate the integrated design and figure numbers followed by “b” will indicate the isolated design.

As shown in Fig-11a & 11b, the seat ring sub assembly is done outside during the valve assembly. Two sets of seat ring sub-assemblies are inserted in the seat bore of the valve body as shown in Fig-12a & 12b.

Since the springs are not compressed in this position, the seat rings are in fully moved towards the ball. To assemble the ball into the body, these seat rings need be pushed into the valve body in direction away from each other as shown in Fig-13.

This pushing is done using hydraulic cylinder or screw jack mechanism or any suitable aid. The seat rings are pushed away until the springs on either side are compressed and the seat ring touches the extreme end as shown in Fig-14a & 14b.

In this pushed condition, the seat rings are to be locked in that position so that the pushing aid can be taken out and the ball can be entered.

The locking is done in as follows,

Locking in Integral latch design:
In seat ring fully pushed position, the retainer ring is free to rotate across the slot provided on the latches. By rotating the retainer ring, the seat ring and the hook body are held together circumferentially at three points. This process is called as latching refer Fig-15.

Locking in Isolated latch design:
In seat ring fully pushed position, the latch segments are directly inserted and slide into the closed slot formed by body & seat ring. By this, the seat ring is held in pushed position firmly by the retainer segment & valve body with spring in compressed condition. Refer figure-16 which explains locking sequence of the seat ring using a pair of retainer segment.

The pushing aid can then be released and taken out from the valve body. When the pushing aid is released, the Latch ring/Segment will become loaded. The latch ring or segment cannot be moved or slid until it is unloaded by further retracting seat ring. The retracted seat ring provides the required space for inserting the ball into the body. The ball is inserted in open position in which the face to face of the ball is less as shown in Fig-17.

Then the ball is rotated 90° to accommodate the pushing aid (hydraulic cylinder or screw jack) as shown in Fig-18.

After inserting the ball the latch has to be disengaged to advance the seat ring towards the ball.

By further retracting the seat ring using hydraulic cylinder or screw jack the latch ring/segment will be unloaded & free so that it can be disengaged (slide to unlock position in case of integrated design & remove it out in case of isolated design) . By slowly withdrawing cylinder or screw jack, the seat ring advances towards the ball and engages with it with the required spring load. The pushing aid is now removed and the rest of the valve assembly is completed.

DIS-ASSEMBLY
Before disassembly, the valve is kept in closed condition. Valve cover is disassembled in usual manner. Seat rings are pushed and latched as explained in assembly process. Now the ball is rotated 90° and taken out. Seat rings are brought to its disengaged position with pushing aid by de-latching as explained in assembly process.

ADVANTAGES OF THE INVENTION:
- Simple and faster assembly/disassembly process
- Amount of spring compression is independent of assembly.
- Body puncturing is eliminated.
- Effort required to dismantle the seat ring is minimum.
- Possibility of seat ring jamming is eliminated.
- Locking is done internally.

THE INVENTIVE STEP OF THE INVENTION
- Two types of Hook & Latch mechanism for top entry trunnion mounted ball valve
- Freely rotating retainer ring.
- Self-locking arrangement for top entry seat ring
- Locking the seat ring through slots on the seat ring

The disclosure has been made as known to inventors and with specific examples and illustrations for the purpose of proper disclosure and better understanding of the invention. There can be other variations and modifications that will be obvious to skilled persons in the art. All of such variations and modifications are within the scope of invention.