GB2186347A

GB2186347A - Ball valve

Info

Publication number: GB2186347A
Application number: GB08700668A
Authority: GB
Inventors: Karl-Heinz Haense
Original assignee: SEPPELFRICKE GEB GmbH
Current assignee: SEPPELFRICKE GEB GmbH
Priority date: 1986-02-07
Filing date: 1987-01-13
Publication date: 1987-08-12
Also published as: IT8622392A1; GB8700668D0; BE1000013A6; IT8622392A0; GR862636B; GB2186347B; IT1198122B

Abstract

In a ball valve comprising a metallic valve housing (1) and a metallic shut-off ball (3) with which there co- operate in sealing manner sealing rings (5) of an elastomer which are arranged in the valve housing (1) at the entry of the housing circulation passages (4) into the housing ball chamber (2), for fireproofing of the ball valve the entries of the circulation passages (4) into the housing ball chamber (2) are surrounded, in addition to the elastomer gaskets, by copper sleeves (9) which are inserted with sealingly close fit into housing recesses (10) and of which the sleeve edge protruding into the ball chamber (2) abuts with sealing contact on the shut-off ball (3). Preferably the spindle (6) is of bronze, the housing (1) of brass or steel, and the ball (3) of chromium-plated brass or high-grade steel. <IMAGE>

Description

SPECIFICATION Ball Valve The invention relates to a ball valve having a valve housing and a shut-off ball of metal and having sealing rings of an elastomerwhich surround the entries of the housing circulation passages into the housing ball chamber and co-operate in a sealing manner with the shut-off ball, the metallic spindle of which protrudes through a spindle bore of the housing.

A demand for fireproof quality in the case of building fires or the like is increasingly made of those fittings for gas conduits where seals or packings of non-metallic material, such for example as synthetic plastics material, are used in order to connect metallic fitting parts in sealed manner with one another or to move them in relation to one another in sealed manner. According to one directive for safety testing, adequate fireproof quality is present if after half an hour of heating to 650"C the fitting has suffered no leakages permitting the passage of morse than 150 litres of gas per hour at the ordinary gas conduit pressure up to 4 bars.

Temperatures of the above-mentioned level lead to destruction of the elastic synthetic plastics gaskets usual in ball valves of metal, which under normal conditions effect the seal between the valve housing and the rotatable shut-off ball and frequently are also used for the sealing mounting of the ball spindle in the housing spindle bore.

The problem to be solved by the invention is of forming a ball valve of the initially stated kind so that a fireproof quality still fulfilling the requirements is achieved even in the case of destruction of the elastomer gaskets caused by heat orfire.

In accordance with the invention this problem is primarily solved in that the entries of the housing circulation passages into the housing ball chamber are additionally surrounded by copper sleeves which are inserted with close fit sealing into housing recesses and of which the sleeve edge protruding into the ball chamber rests with sealing contact on the shut-off ball. If destruction of the elastomer gaskets by heat should occur, these sleeves maintain a metal-to-metal seal between the valve housing and the shut-off ball which still satisfies the fireproofing requirements.Ordinary commercial pure copper material is suitable, especially on account of its greater softness compared with bronze material of high percentage copper content, with especial advantage for the sleeves, which in the case of metallic contact do not damage the shut-off ball, consisting for example of chromium-plated brass. Copper sleeves of softer, ordinary commercial pure copper can also be produced with a predetermined plus tolerance in the sleeve length and then subsequently deformed in assembly of the ball valve by pressure in the sleeve longitudinal direction against the shut-off ball, so that the sleeve edge protruding into the ball chamber adapts itself to the ball form and abuts on the shut-off ball with the tightness ensuring fireproof quality.

Elastomer gaskets are in fact used in ball valves for gas conduits in order to seal off the rotatable ball spindle in the housing spindle bore connected with the housing ball chamber. If the metal parts of the ball valve are produced from copper alloy, usually brass is used on account of its substantially lower price compared with bronze. In the case of a brass ball valve it has however appeared that the ball spindle of brass, originally mounted practically without play in the housing spindle bore, has experienced such shrinkage after heating of the fitting to the initially mentioned test temperature of 650 C, that the bearing play between brass spindle and housing spindle bore does in no case still have gas-tightness sufficing for the fireproofing requirements, when the gaskets are burned.On account of this ascertained shrinkage in the case of brass, brass is also unsuitable for the sleeves cooperating in sealing manner with the shut-off ball in accordance with the invention. For the region of the rotatable mounting and fireproof sealing of the ball spindle in the valve housing, according to a further development feature, the invention provides that the spindle comprises circumferential parts which fill out the housing spindle bore with as far as possible play-free fit, and that in this case the spindle consists of bronze. It has been found that in contrast with the conventional brass ball spindle, a ball spindle of bronze on heating to the test temperature surprisingly displays no shrinkage and a fitting seating of the spindle in the spindle bore, originally produced without play if possible, is maintained after heating.Thus in a simple manner with a ball spindle of bronze it is possible when the gaskets are burned still to retain a metal-to-metal seal between ball spindle and valve housing which still suffices for fireproofing requirements.

An example of embodiment of a ball valve according to the invention is represented in longitudinal section in the drawing.

The ball valve comprises a metallic valve housing 1 (for example of brass or steel) and a metallic shutoff ball 3 (for example of chromium-plated brass or high-grade steel) rotatable in the housing ball chamber 2. At the entry of the housing circulation passages 4 into the housing ball chamber 2, the housing 1 of the valve contains elastic synthetic plastics gaskets 5 which abut in sealing manner on the shut-off ball 3. The metallic ball spindle 6 is likewise sealed off in the spindle bore 8 of the valve housing by means of synthetic plastics gaskets 7.

So that a fireproof seal is still maintained in the case of a failure of elastomer gaskets due to the action of heat, the entries of the housing circulation passages 4 into the housing ball chamber 2 are additionally surrounded by copper sleeves 9. For this purpose the housing circulation passages 4 are formed with housing recesses 10 into which the copper sleeves 9 can be inserted from the housing ball chamber 2 and are pressed with such a sealingly close fit that the metallic contact between the sleeves and the housing is gas-tight. The edge of each copper sleeve 9 protruding into the ball chamber 2 abuts with sealing contact on the shut-off ball 3. In order to achieve this reliably and simply, the sleeves consisting of relatively easily and smoothly deformable copper can be dimensioned somewhat longer than necessary so that in the assembly of the ball valve the sleeves are pressed against the shut-off ball and adapt themselves with closely abutting sleeve edge to the ball form. The ball spindle 6 possesses circumferential parts 11 which fill out the housing spindle bore 8 with a diameter so as to be as free as possible from play; the spindle 6 further consists of bronze which on heating of the spindle to a temperature leading to destruction of the gaskets involves no shrinkage of diameter of the spindle and permits the retention of the sealing of the narrow fit of spindle and spindle bore which is necessary for fireproofing.

Claims

1.A A ball valve having a valve housing and a shut- off ball of metal and having gaskets of an elastomer which surrounds the entries of the housing circulation passages into the housing ball chamber and co-operate in sealing manner with the shut-off ball, a metallic spindle protruding through a spindle bore of the housing, in which the entries of the housing circulation passages into the housing ball chamber are additionally surrounded by copper sleeves which are inserted with sealingly close fit in housing recesses and in which the sleeve edge protruding into the ball chamber abuts with sealing contact on the shut-off ball.

2. A ball valve according to claim 1, in which the spindle of the shut-off ball comprises circumferential parts which fill out the housing spindle bore with a fit as free as possible from play, and in which the spindle is made of bronze.

3. A ball valve according to claim 1 substantially as hereinbefore described with reference to the drawing.