GB2026628A

GB2026628A - Seals

Info

Publication number: GB2026628A
Application number: GB7924734A
Authority: GB
Original assignee: LOUTH R
Current assignee: LOUTH R
Priority date: 1978-07-26
Filing date: 1979-07-16
Publication date: 1980-02-06
Also published as: GB2026628B

Abstract

A gland 20 for compressing the packing rings 16 in the stuffing box 14 of a seal surrounding a shaft 12 passing through the wall 10 of a pressure vessel includes an annular member 50 contacting the outermost packing ring the member being connected to the piston of a piston 42 and cylinder 22 device which is supplied with pressurised hydraulic fluid to ensure that the packing rings are compressed constantly during operation. The piston and cylinder device may be annular such that it can be arranged around the shaft. Inlet and exhaust ports 52, 54 for the fluid are provided in the cylinder. <IMAGE>

Description

SPECIFICATION Improvements in or Relating to Glands The present invention concerns improvements in or relating to glands.

Glands are well known for use in conjunction with stuffing boxes to provide a fluid tight seal between a rotatable shaft or reciprocating rod where it passes through the wall of a pressure vessel or the like.

A stuffing box comprises a cylindrical recess around the shaft, the recess containing a packing, normally in the form of annular rings, which is compressed in the stuffing box by the gland to increase its sealing contact with the outer surface of the shaft. The gland is often attached to the pressure vessel by bolts or the like whereby the packing may be compressed by tightening down the bolts.

This arrangement is disadvantageous, especially in sealing arrangements for large shafts as, owing to wear, the packing reduces in size. To maintain the compression in the packing it is necessary to frequently further tighten down the bolts.

It is an object of the present invention to obviate or mitigate these disadvantages.

According to the present invention there is provided a gland for a packed seal, comprising a cylinder and a piston movabie therein, fixing means for holding the cylinder relative to a pressure vessel to be sealed, an annular member connected to the piston and adapted to abut and compress the packing of the seal, and inlet and exhaust means for introducing and exhausting fluid to and from the cylinder.

Preferably the cylinder is annular and surrounds the shaft protruding through the pressure vessel. Correspondingly the piston is annular and connecting members in the form of rods are provided to fix it to the said annular member.

Preferably a closure plate is provided for each end of the cylinder whereby the cylinder may be double acting.

Preferably the piston is provided with O-rings at its outer and inner surfaces.

Preferably an O-ring is provided between said connecting members and the closure plate.

Preferably the cylinder comprises an inner and an outer sleeve, the outer sleeve having an inwardly directed flange forming one end closure plate and the inner sleeve having an outwardly directed flange forming the other end closure plates, the sleeves being an interference fit one between the other.

An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawing which shows part of a pressure vessel wall, a rotatable shaft protruding therethrough and a gland and packing for sealing the clearance between the shaft and the wall.

The pressure vessel wall 10 is penetrated by a circular cross-section rotatable shaft 12 and a stuffing box 14 is provided in the pressure vessel wall around the shaft by forming a recess in the wall. Rings of suitable packing material are fitted into the stuffing box in rubbing contact with the outer surface of the shaft 12.

A gland, generaily designated by the reference numeral 20, is provided to compress the packing rings 1 6 to enhance the seal around the shaft. The gland comprises an annular cylinder 22 having a removable end plate 24 threadably mounted therein. The cylinder 22 comprises an inner sleeve 24 having an outwardly directed flange 26 having a plurality of equipsaced circular cross-section passages 28 therethrough, each passage 28 being recessed to house an O-ring 30. An outer sleeve 32 of the cylinder has an internal diameter substantially equal to the external diameter of the flange 26 and an inwardly directed flange 34 at the end, the internal diameter of the flange 34 being substantially equal to the external diameter of the sleeve 24. A recess 36 is provided in the inner circumference of the flange 34 and houses an O-ring 38.In view of the diameters of the sleeves and their flanges the cylinder may be assembled by interference fitting the inner within the outer and to ensure the correct relative positioning of the sleeves an inwardly directed stop 40 is provided on the outer sleeve 32.

An annular piston 42 is slideably mounted in the cylinder and is provided with O-rings 44 in recesses 46 in the inner and outer circumferences thereof. A plurality of equispaced circular crosssection connecting rods 48 extend from the piston 42 through the passages in the flange 26 and are fixed at their outer ends to an annular member 50 which abuts the packing rings 16.

Inlet and exhaust ports 52, 54 are provided in the cylinder 22 which conveniently has a fixing flange 56 attached to the outer sleeve 32 whereby it may be fixed by studs, only the centre line 58 of which are shown, to the pressure vessel wall 10.

In operation with the piston 42 withdrawn to the end of the cylinder 22 furthest from the wall 10, the packing rings 1 6 are introduced into the stuffing box 14 and the gland 20 is fixed to the wall 10 by the studs. Hydraulic fluid under pressure is supplied to the port 52 of the cylinder so that the piston is caused to travel towards the wall 10 thereby compressing the packing rings in the stuffing box. The seal is then operational and during operation pressurised hydraulic fluid is continually supplied to the port 52 whereby a constant force is exerted on the packing. It will be realised therefore that as the packing reduces in size owing to wear the compressive force thereon is maintained as annular member 50 advances into the stuffing box.When it is desired to introduce fresh packing rings into the stuffing box either to completely replace the packing or to augment the packing already therein, pressurised hydraulic fluid is applied to the port 54 such that the piston retracts into the cylinder allowing access to the stuffing box and thus the introduction of fresh packing rings. Thereafter the compressive force on the packing can be applied -by reintroducing pressurised fluid to the cylinder by way of port 52.

Various modifications can be made without departing from the scope of the invention. For example the piston and cylinder can assume different shapes. Furthermore the construction of the gland is such that it can readily be manufactured by machining from metal or from any suitable plastics material.

The embodiment described above provides a gland which, as it constantly applies pressure to the packing in the stuffing box, results in less maintenance time being required and furthermore, in view of the ease of piston retraction, enables the packing to be augmented or replaced with the minimum down time.

Claims

1. A gland for a packed seal, comprising a cylinder and a piston movable therein, fixing means for holding the cylinder relative to a pressure vessel to be sealed, an annular member connected to the piston and adapted to abut and compress the packing of the seal, and inlet and exhaust means for introducing and exhausting fluid to and from the cylinder.

2. A gland as claimed in claim 1, in which the cylinder is annular and surrounds the shaft protruding through the pressure vessel.

3. A gland as claimed in claim 2, in which the piston is annular and connecting members in the form of rods are provided to fix it to the said annular member.

4. A gland as claimed in any one of claims 1 to 3, in which a closure plate is provided for each end of the cylinder whereby the cylinder may be double acting.

5. A gland as claimed in claim 3 or claim 4, in which the piston is provided with O-rings at its outer and inner surfaces.

6. A gland as claimed in any one of claims 3 to 5, in which an O-ring is provided between said connecting members and the closure plate.

7. A gland as claimed in any one of claims 2 to 6, in which the cylinder comprises an inner and an outer sleeve, the outer sleeve having an inwardly directed flange forming one end closure plate and the inner sleeve having an outwardly directed flange forming the other end closure plates, the sleeves being an interference fit one between the other.

8. A gland substantially as hereinbefore described with reference to the accompanying drawings.

9. Any novel subject matter or combination including novel subject matter herein disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.