FR2484597A1 - Protective washer for drive spindle of lift valve - is sited between valve body and spindle casing to prevent fluid penetrating spindle thread - Google Patents

Abstract

The protective washer (14) may be made of graphite or PTFE being used to protect the thread (7a) of a valve- actuating rod (7). The valve comprises a body (1) surmounted by a cover (2) in the form of a hollow column, the latter contg. the actuating rod on which is mounted a handwheel (11). A length (7a) of the rod is upset and threaded to be located by a threaded section (13) of the cover (2) bore, and a rod is rotated to lift or lower the valve organ (8). A washer (14) is sited between the cover bore and a passage (10) penetrated by conveyed fluids. The cover base may be recessed (15) to locate the washer with retaining washers (15) which are clamped in position by studs (3).

Description

Device for protecting an internal thread of a valve.

 The present invention relates to a device for protecting an internal thread of a valve.

 Valves, such as direct flow valves or globe valves, generally include a body on which is fixed a cap and in which is pivotally and slidingly mounted a control rod which carries at one of its ends a shutter member and at the other end a handwheel. Certain operating devices of a valve fitting have an internal thread on the control rod, which has a significant drawback due to the contact between the vehicle fluid and the thread of the control rod. is not always very clean and often contains solid particles in suspension, it follows that this contact between the fluid and the thread can cause two phenomena.

Indeed, there may be a washing of the thread by the fluid and, consequently, a "dry" operation of the system without grease> which leads to more or less long term seizure of the control rod.

 Furthermore, penetration inside the thread of the solid particles contained in the fluid inevitably also leads to seizure of the control rod. Consequently, the object of the invention is a device making it possible to protect the thread in order to ensure the reliability of the devices.

According to the invention, there is between the body and the cap a ring engaged around a cylindrical part of the control rod, said ring being interposed between the passage of fluid in the body of the valve and the thread of the control rod.

 This ring does not achieve an absolute seal, but a filtering of the fluid passing through the valve and a retention of the grease disposed in the part of the valve containing the thread.

Other characteristics and advantages of the invention will be better understood on reading the following description of an embodiment and with reference to the accompanying drawings, in which
- Figure 1 is a longitudinal sectional view of a direct-flow gate valve provided with the device according to the invention
- Figure 2 is an enlarged view of the device for protecting an internal thread according to the invention.

 In Figure 1, there is shown a gate valve which comprises a body 1 on which is fixed a cap or head 2 by means of screws 3 and nuts4 engaged in holes provided on the flanges 5 and 6 of the body 1 and hat or tette 2.

Inside the cap 2 and the body 1 is slidably and rotatably mounted a control rod 7 which is provided at one of its ends in the body with a cover or shutter 8 engaged between two seats 9, 9a integral with the body and arranged in the conduit 10 for circulation of the fluid in the body. At its other end extending outside the body, the control rod 7 is provided with a flywheel 11 fixed by means of a nut 12.

 In its middle part, the rod 7 has a threaded part 7a which is engaged in a threaded hole 13 formed in the cap 2.

Around the cylindrical part 7b of the control rod 7 is engaged a ring 14 (FIG. 2) made of graphite or tdtra-fluoroethylene which is engaged in a housing 15 formed in the cap 2, said ring 15 being disposed between two rings of holding 16, 16a in support respectively against the bottom of the housing 15 and against a face of the body 1. Between the body 1 and the cap 2 is disposed a seal 17 outwardly.

This arrangement makes it possible to isolate the threaded part 7a of the control rod from the part of the body 1 in which the fluid or liquid circulates, by means of the ring 14 which does not achieve absolute sealing, but filtering of the fluid and a grease retainer arranged around the threaded part.

 At the cylindrical upper part of the rod 7, a chamfer 18 is provided which is capable of coming into abutment against a chamfer 19 formed on the cap and constituting a rear sealing system for the possible reloading of lubrication product.

Of course, other modifications can be made by those skilled in the art to the embodiment described without departing from the scope of the invention.

Claims (5)

 1. Device for protecting an internal thread of a valve fitting comprising a body on which a cap is fixed and in which the control rod is dice which carries at one of its ends a shutter member and which has a threaded part engaged in a threaded hole in the cap, characterized in that, between the body (1) and the cap (2) is arranged a ring (14) engaged around a cylindrical part (7b) of the rod control (7), said ring (14) being interposed between the passage (10) of fluid from the valve and the thread (7a) of the control rod. 2. Device according to claim 1, ca acterized in that, on either side of the protective ring (14) are arranged retaining rings (16, 16a). 3. Device according to claim 1, ca acterized in that the protective ring (14) is made of graphite. 4. Device according to claim 1, ca acterized in that the protective ring (14) is made of lytetrafluoroethylene. 5. Device according to claims 1 and 2, characterized in that the protective ring (14) and the retaining rings (16, 16a) are engaged in a housing of the cap (2) and are held tight between flanges (5 , 6) of the cap and the body assembled by means of screws (3) and nuts (4).