WO2011099866A1

WO2011099866A1 - A stem extension for a valve, and an insulation system comprising said stem extension

Info

Publication number: WO2011099866A1
Application number: PCT/NO2011/000047
Authority: WO
Inventors: Geir Gulliksen
Original assignee: Bis Industrier As
Priority date: 2010-02-09
Filing date: 2011-02-07
Publication date: 2011-08-18

Abstract

A stem extension (1; 1 ') is provided for a valve (3; 3'), comprising a first extension shaft portion (9; 9') connected to the valve (3; 3') spindle, a second extension shaft portion (10; 10') connected to a control device (11; 21) for the stem extension (1; 1 ') for controlling the valve (3; 3') by means of the control device (11; 21). A heat or cold refractive shaft portion (12; 12') with low heat transfer coefficient in relation to the first and second extension shaft portions (9, 10; 9', 10') is arranged between the first and second extension shaft portions (9, 10; 9', 10'). An insulation system comprising a stem extension (1; 1 ') and an insulation casing (4) is also provided.

Description

A stem extension for a valve, and an insulation system comprising said stem extension.

The present invention relates to a stem extension for a valve and an insulation system comprising said stem extension, e.g., for cryogenic application. More specifically, the invention relates to a stem extension and an insulation system as disclosed in the preamble of claim 1 and claim 9, respectively.

In cryogenic plants, for example, for the production of LNG at a temperature of about -163°C, insulation must be provided carefully around the valves that are components of the plant in order to prevent thick ice formation around the valves due to the low temperature of the medium flowing through them, as such ice formation would prevent operation of the valves. The insulation may typically consist of a casing of cellular or foamed glass elements arranged in several layers around each respective valve, and around which casing there is advantageously arranged a vapour barrier and an outer layer of metal for mechanical protection.

A problem with the aforementioned solution is that the valve is not designed for cryogenic insulation, and has a design which in practice makes it impossible to maintain the insulation thickness and also that vapour tightness at the neck/stem of the valve is made difficult. A lack of insulation and vapour tightness will, under cryogenic conditions, as is known, result in formation of ice.

The aforementioned and/or other problems are sought to be solved by means of a stem extension and an insulation system as disclosed in the characterising clause of claim 1 and claim 9, respectively.

Advantageous embodiments of the invention are set forth in the dependent claims.

The invention is explained in more detail below with the aid of non-limiting

embodiments, and with reference to the attached drawings, wherein:

Fig. 1 is a perspective view of a first embodiment of a stem extension according to the invention mounted on a gate valve arranged in a cryogenic insulation casing, where

Fig. 2 is a larger perspective view of the stem extension shown in Fig. 1 ; Fig. 3 is a transparent side view of the stem extension shown in Figs. 1 and 2;

Fig. 4 is a perspective view of a second embodiment of a stem extension according to the invention mounted on a ball valve arranged in a cryogenic insulation casing;

Fig. 5 is a larger perspective view of the stem extension shown in Fig. 4; and

Fig. 6 is a transparent side view of the body of the stem extension shown in Figs. 4 and 5.

Fig. 1 - 3 show a first embodiment of a stem extension 1 according to the invention, fastened to the control wheel 2 of a gate valve 3 arranged in a cryogenic insulation casing 4, which gate valve 3 constitutes a part of a fluid flow path in, for example, a cryogenic processing plant for the production of LNG at such a low temperature as -163°C. The insulation casing 4 around the gate valve 3 must, as mentioned above, ensure good insulation and air tightness against the external environment in order to prevent detrimental ice formation around the gate valve 3.

As shown in particular in Figs. 2 and 3, the stem extension 1 comprises a first 5 and a second 6 fastening washer for securing the gate valve 3 control wheel 2 between the fastening washers 5, 6 with the aid of a plurality of bolts 7 passed through respective aligned openings 8 in the fastening washers 5, 6. The first fastening washer 5 is arranged at one end of a first extension shaft portion 9, the stem extension 1 also comprising a second extension shaft portion 10, which at one end is secured to a control wheel 11 and which at another end is connected to the extension shaft portion 9 via a cold refractive shaft portion 12 with low heat transfer coefficient, e.g., of cold-resistant plastic and which at the operating temperatures in question is capable of transferring the torque created by turning the control wheel 11.

The extension shaft portions 9, 10 are advantageously hollow, cylindrical tubes, and around each of the extension shaft portions 9, 10 there is sealingly arranged two ball bearings 13, 14. Instead of, or in addition to, the ball bearings 13, 14 there may alternatively or additionally be provided non-illustrated shaft seals, one purpose of the ball bearings 13, 14 and/or shaft seals being to form an essentially airtight space around the cold refractive shaft portion 12. This is achieved as a cold-resistant sleeve 15, advantageously of plastic, is sealingly arranged around each bearing 13, 14 and/or shaft seal. A cover 16 advantageously surrounds a part of the extension shaft portion 10 and the sleeve 15, one end of the cover 16 bearing against the control wheel 11 of the stem extension 1, the control wheel 11 being advantageously fastened to an end of the extension shaft portion 10 with a bolt 17. As indicated in Figure 1, a part of the insulation casing 4 is sealingly secured, e. g., by using a suitable adhesive or sealing mass such as silicone, to a circumferential face of the sleeve 15, such that the inner space 18 in which the gate valve 3 is arranged is essentially airtight in relation to the external environment outside the insulation casing 4. An airtight sealing similar to that between the sleeve 15 and the insulation cover 4 is thus also anticipated between the elements 19, 20 respectively adjacent to the gate valve 3 in the fluid flow path and the insulation casing 4. The fact that the gate valve 3 is arranged airtight in the insulation casing 4 thus ensures external weather sealing for the gate valve 3 arranged within the insulation casing 4 when the insulation box 4 with the gate valve 3 is located outdoors, for example, in connection with a processing plant, and which inhibits corrosion of the gate valve 3.

Apart from in particular the cold refractive shaft portion 12 and the sleeve 15, the valve extension 1, for reasons of strength and production, is advantageously of metal.

In certain types of gate valve 3, the control wheel 2 will be stationary in the longitudinal direction for a non-illustrated valve spindle to which the control wheel 2 is connected, whilst a part of the valve spindle will move in the longitudinal direction out from the centre of the control wheel 2 when the control wheel is turned in one direction, or in from the centre of the control wheel 2 when the control wheel 2 is turned in an opposite direction. As the extension shaft portion 9 is advantageously hollow, the valve spindle will also not be obstructed in its movement when the stem extension 1 is connected to the gate valve 3.

In certain other types of gate valves 3, the control wheel 11 will move in a longitudinal direction for a non-illustrated valve spindle connected to the control wheel 2, and in this case the movement in the longitudinal direction must be compensated using suitable means for ensuring air tightness, e.g., in that the ball bearings 13, 14 are allowed to slide sealingly in the longitudinal direction against an inner circumferential surface of the sleeve 15, or in that the extension shaft portion 9 is provided as a telescopic element with an inner part having a rectangular cross-section within a hollow outer part with a corresponding rectangular cross-section, and where the shape of the cross-section ensures torque transfer over the extension shaft portion 9 upon operation of the control wheel 11. For gate valves of this type, it must of course be ensured during installation that there is room in the region of the control wheel 3 which allows it to be moved in the longitudinal direction.

Figs. 3 - 6 show a second embodiment 1 ' of the stem extension according to the invention, for connection to one end of the valve spindle of a ball valve 3' after the ball valve's 3 'control lever 21 has first been dismounted from the valve 3' and optionally moved to an end of the stem extension 1 ', or that the stem extension 1 includes a separate control lever 21. The stem extension Γ thus differs from the stem extension 1 shown in Figs. 1 - 3 in that the fastening washers 4, 5 are replaced by an essentially rectangular fastening member 22 and that the control wheel 11 is replaced by a control lever 21. As shown, there is an opening 23 in the fastening member 22 for fastening the ball valve 3' valve spindle to the fastening member 22 with a nut 24. At another end of the stem extension , the control lever 21 is fastened to the extension shaft portion 10' of the stem extension 1 ' by means of a screw 17'. The parts of the stem extension Γ which are the same as for the stem extension 1 are thus designated by the same reference numeral but with an apostrophe (').

In the ball valve 3', the valve spindle thereof and the control lever 21 attached to the valve spindle will typically be moved 90° between an open and a closed position without the valve spindle or the control lever moving in the longitudinal direction, and the problem with longitudinal motion for certain types of gate valves 3 as mentioned above will thus not be a relevant issue for a ball valve 3'.

Also in other, non-cryogenic connections, for example, for fire protection, it may be desirable to have a stem extension 1, 1 ' according to the invention, the valve 3, 3' then being advantageously arranged within a fire-insulating insulation casing 4 and where the shaft portion 12, 12' will then have a heat refractive function with a low heat transfer coefficient and where the shaft portion 12, 12' and the sleeve 15, 15 'are of heat- resistant materials.

The present invention thus also relates advantageously to an insulation system including the stem extension 1, and the insulation casing 4.

Although the designation "stem extension" is used in the description and in the claims, it is not intended to limit the invention to valves provided with a valve stem. What is essential in this connection is that the operating or activating point is moved out from the valve without the structure of the valve having to be altered, as the stem extension is connected to the valve's physical operating point, such as a stem or control shaft.

Claims

P a t e n t c l a i m s 1.

A stem extension (1 ; ) for a valve (3; 3 '), characterised by comprising a first extension shaft portion (9; 9') connected to the valve's (3; 3') control shaft or spindle, a second extension shaft portion (10; 10') connected to a control device (11; 21) for the stem extension (1; ) for manual control of the valve (3; 3') by means of the control device (11; 21), a heat or a cold refractive shaft portion (12; 12') with low heat transfer coefficient in relation to the first and second extension shaft portions (9, 10; 9', 10') being arranged between the first and second extension shaft portions (9, 10; 9', 10').

2.

A stem extension according to claim 1, characterised in that the extension shaft portions (9, 10; 9', 10') are cylindrical tubes, and that around each extension shaft portion (9, 10; 9', 10') is sealingly arranged a respective ball bearing (13, 14; 13', 14').

3.

A stem extension according to claim 1, characterised in that the extension shaft portions (9, 10; 9', 10') are cylindrical tubes, and that around each extension shaft portion (9, 10; 9', 10') is sealingly arranged a respective shaft seal.

4.

A stem extension according to claim 1, characterised in that the extension shaft portions (9, 10; 9', 10') are cylindrical tubes, and that around each extension shaft portion (9, 10; 9', 10') is sealingly arranged a respective ball bearing (13, 14; 13', 14') and a respective shaft seal.

5.

A stem extension according to claims 2 - 4, characterised in that around each ball bearing (13, 14; 13', 14') or shaft seal is sealingly arranged a sleeve (15; 15'), the sleeve (15; 15') and the heat or cold refractive shaft portion (12; 12') being of materials that are resistant at the relevant exposure temperatures.

6.

A stem extension according to claims 2 - 5, characterised in that a cover (16; 16') surrounds a part of the extension shaft portion (10; 10') and a part of the sleeve (15; 15'). A stem extension according to any one of the preceding claims, characterised in that to one end of the extension shaft portion (9) is attached a first (5) and a second (6) fastening washer, and that to one end of the extension shaft portion (10) is attached a control wheel (11).

8.

A stem extension according to any one of claims 1 - 6, characterised in that to one end of the extension shaft portion (9') is attached a fastening member (22) and that to one end of the extension shaft portion (10') is attached a control lever (21).

9.

An insulation system comprising stem extension (1, ) according to any one of claims 4 - 8, characterised in that an insulation casing (4) is arranged around a valve (3; 3') to which the stem extension (1; Γ) is connected, the stem extension (1; ) projecting through the insulation casing (4) such that the stem extension (1; 1 ') control device (11; 21) is located on the outside of the insulation casing (4).

10.

An insulation system according to claim 9, characterised in that between the sleeve (15; 15') and the insulation casing (4) is arranged a sealing mass, such as silicone, or an adhesive in order to secure substantial air tightness between an inside and an outside of the insulation case (4).

11.

An insulation system according to claim 9 or 10, characterised by being a cryogenic insulation system.

12.

An insulation system according to claim 9 or 10, characterised by being a fire insulation system.