GB937399A - Gland packing - Google Patents

Abstract

937,399. Stuffing-boxes. SULZER FRERES S.A. Aug. 17, 1962 [Aug. 17, 1961; Oct. 20, 1961], No. 31727/62. Class 122 (5). A sealing gland assembly comprises at least one lipped sealing ring having a lip part 2, Fig. 1, in contact with a member 18 to be sealed and a shorter and stouter supporting part 3 pressed at its back 9 by means of a ring 1 axially against a ring 5, the facing surfaces 4, 8 of the part 3 and of the ring 5 being so disposed in relation to each other that, when only a light axial tightening force is applied to the gland, they are only partially in contact and a gap 16 is left between them which widens radially outwardly from the lip, the gap being progressively narrowed as the axial tightening force is increased. The surfaces 4, 8 are of frusto-conical shape; alternatively, one or both of the surfaces may be curved in cross-section. The back 9 of the part 3 is curved, or it may be straight, and the corresponding surface 12 of the ring 1 is of similar shape. In Fig. 6, the surfaces 4, 9 of the part 3 are arcuate and the surfaces 8, 12 of the rings 1, 5 are normal to the gland axis. An opening 43 may be provided in the region of the supporting part 3 where its inner boundary wall 6 adjoins the lip 2. The lipped ring may be made wholly of one material, Fig. 1, such as rubber, fabricreinforced rubber or a synthetic plastic such as nylon; alternatively, Fig. 6, the lip may be made of synthetic plastic and is bonded at the surface 40 to a resilient metal part 3. In Fig. 7, the lip 2 is fastened on or in the supporting part 3 which is in the form of a dished ring, the faces 4, 9 of which are inclined to the gland axis. Alternatively, these faces are normal to the axis and the faces 8, 12 of the rings 1, 5 are inclined. The maximum deformation of the part 3 on tightening is limited by the maximum axial dimension U of the cavities 16, 44. In Fig. 2, two groups of rings 19, 19<SP>1</SP> act in opposite direction to prevent passage of fluid medium respectively from spaces 21, 23 towards a space 22. The rings are mounted in radially adjustable cylindrical casings 25, 25<SP>1</SP>. A ring 20 or 20<SP>1</SP> disposed between two lipped rings engages respectively the back of one and the front of the other of said rings. When tightening the gland, e.g. of Fig. 1, the resultant of the reaction forces at the contact area between the surfaces 4, 8 produce with the opposing tightening force a couple, Fig. 3, which cause deformation of the lip 2 radially inwards thus increasing its contact with the member 18. As tightening increases the contact area between the forces 4, 8 increases and the resultant of the reaction forces gradually shifts its line of action radially outwards. Under these conditions the couple exerted reaches a maximum value until, upon further tightening, it is finally reversed resulting in the lip being lifted away from the member 18. and seizure between the lip and the member is avoided in case of excessive tightening of the gland,