Title of Invention

A LUBRICATED PLUG VALVE

Abstract

A lubricated plug valve comprising a valve body accommodating a rotatable plug for controlling the flow of fluid therethrough; a stem connected to the plug for rotating the plug; a circular packing groove on the stem aligned with the hole of a packing injector for receiving under pressure a packing compound within the groove, characterised by a chamber surrounding the stem, above the packing groove, said chamber containing an elastomer seal whereby any leak of fluid from the packing groove, along the side of the stem, is stopped by the said elastomer seal.

Full Text

This invention relates to a lubricated plug valve. The known lubricated plug valve has a flow passage having an inlet and outlet for the inflow and the outflow of fluid through a plug. The plug, when rotated by a stem and connected thereto^ Controls the flow of fluid through the valve the stem. A ;rapfiiwT^acttg compound under pressure into the packing groove to serve as a sealant for arresting leak of the fluid from the valve. However, after several operations, the pressure of the packing in the groove diminishes and the fluid handled by the valve commences to leak past the packing groove, along the side of the stem. Accordingly this invention proposes a lubricated plug valve having a secondary sealing arrangement which effectively stops the leak from the packing groove traveling along the stem. In the case of the plug values with non-threaded stems 0-rings may be used as a secondary sealing arrangement because such stem have only a rotary movement. On the other hand, in cases of plug valves which have threaded stems which execute not only a rotary movement, but also an up and down movement, 0-rings will not be workable due to the combine rotary and up and down movement of the stem. This invention therefore proposes a secondary sealing arrangement which effectively stops the leak in the case of threaded steams. Needless to say, the proposed sealing arrangement will equally be applicable to non-threaded stems. Various other features of this invention will be apparent from the following further description. The lubricated plug valve, according to this invention comprises a valve body accommodating a rotatable plug for controlling the flow of fluid therethrough ; a stem connected to the plug for rotating the plug: a circular packing groove on the stem aligned with the hole of a packing injector for receiving, under pressure, a packiuR compound within the groove, characterized by a chamber surrounding the stem, above the packing groove, said chamber containing an elastomer seal whereby any leak of fluid from the packing groove, along the side of the stem, is stopped by the said elastomer seal. This invention will now be described with reference to the accompanying drawings which illustrate, by way of example, one of possible embodiments of the lubricating plug valve proposed herein. Fig. 1 illustrating a part of the valve with plug and stem And Fig.2 also illustrating a part of the valve showing the packing groove and the chamber containing the elastomer seal. A valve body V accommodates a rotatable plug P for controlling the flow of fluid therethrough. A stem S is connected to the plug P by an equaliser ring E. A circular packing groove G on the stem S is aligned with a hole H in the body following the packing injector I for receiving, under pressure, a packing compound C, such as, a graphite packing compound, within the groove. This packing compound prevents leak of the fluid handled by the valve. What is stated above are the know features of the valve. The novel features of the valve proposed herein are these: After several operations of the valve, the packing pressure inside the packing groove diminishes causing a leakage path for the fluid handled by the valve to be established along the side of the stem. This path is indicated by T. In order to meet this situation, a chamber M surrounding the stem S is provided. Such chamber M located above the packing groove G contains an elastomer seal F held in place by an anti-extrusion ring R. When the leak of fluid reaches the chamber M, it is stopped by the elastomer seal F from any further flow thereby preventing the leak from spilling out of the valve and also obviating the need for the frequent injection of packing compound into the groove G. An example of the elastomer seal that is used is the commercially avialable quadiing seal. The chamber M is provided in a carrier plate J which is bolted on to the valve body by screws one of which is indicated by K. The lubricated plug valve proposed herein is not confined to the embodiment herein described and illustrated, but other embodiments thereof are possible without departing from the scope and ambit of this invention. We Claim: 1. A lubricated plug valve comprising a valve body accommodating a rotatable plug for controlling the flow of fluid therethrough; a stem connected to the plug for rotating the plug; a circular packing groove on the stem aligned with the hole of a packing injector for receiving under pressure a packing compound witiiin the groove, characterised by a chamber surrounding the stem, above tiie packing groove, said chamber containing an elastomer seal whereby any leak of fluid from the packing groove, along the side of the stem, is stopped by the said elastomer seal. 2. A lubricated plug valve as claimed in Claim 1 wherein the chamber is located above the packing groove and the elastomer seal is held in place by an anti-extrusion ring. 3. A lubricated plug valve as claimed in Claim 1 or Claim 2 wherein the chamber is provided in a carrier plate fixed to the valve body. 4. A lubricated plug valve substantially as herein described and illustrated with reference to the accompanying drawings.

Documents:

468-che-2004-claims duplicate.pdf

468-che-2004-claims original.pdf

468-che-2004-correspondnece-others.pdf

468-che-2004-correspondnece-po.pdf

468-che-2004-description(complete) duplicate.pdf

468-che-2004-description(complete) original.pdf

468-che-2004-drawings.pdf

468-che-2004-form 1.pdf

468-che-2004-form 19.pdf

468-che-2004-form 26.pdf