Patent GB-830422-A (GB)
Title: Improvements in or relating to plugs or closures
Inventor: ROBERTS HENRY
IPC: F16J13/08
Filed: 1957-02-06
Abstract: 830,422. Nuclear reactors. FLIGHT REFUELLING Ltd. Jan. 21, 1958 [Feb. 6, 1957; May 1, 1957; Oct. 15, 1957], Nos. 13911/57 and 32218/57. Class 39(4). [Also in Group XXVIII] A plug 19 comprises a body adapted to make a fluid-tight joint with a peripheral surface on the wall of an opening in a member 11 surrounding the plug, locking means for holding the plug in position in the member and including radially movable locking members 22 in the body adapted to enter a circumferential groove 18 in the wall, a member 44 movable axially in the body between positions in which it respectively holds the locking members in extended positions and allows the locking members to retract and release the plug, and additional locking means, responsive to a pressure differential across the plug, to retain the axially movable member in the position in which it holds the locking members extended. As shown, the plug 19 is adapted to be positioned in a stack-pipe 11 forming a passage leading to an atomic reactor, and includes a cup-shaped centre part 27 provided with a number of radial holes housing balls or rollers 22 freely slidable therein and a frusto-conical shoulder 21 provided with a groove housing a packing ring 23. Extending upwardly from the base of the part 27 is a tubular stem 38 slidably mounted on which is a sleeve 39 having a lower flange 41 and secured to the upper end thereof a cap 43, and an axially movable plunger 44 mounted on the sleeve 39 is recessed at 45 to receive the flange 41 and is formed with a peripheral camming surface 46; springs 51 urged the plunger downwardly. Housed in the part 31 of the plug is a bellows 52 secured in fluid-tight manner to a ring 53 clamped in a recess 54 in the base of the part 27. The lower end of the bellows is attached to a disc 57 carrying a rod 58 extending slidably into the stem 38, contraction of the bellows moving the rod upwardly until the rim of a cup member 59 engages the ring 53. The rod has a frustoconical shoulder 62, and radial holes 63 in the stem 38 accommodate balls 64, the latter being projected into an internal, circumferential groove 65 in the sleeve 39 when the balls 22 are engaged by the part 49 of the camming surface 46 and thereby locking the sleeve to the stem. A central aperture 66 in the part 31 provides communication between the interior of that part and the underside of the plug, and holes 67 in the base of the part 27 connect the interior of the bellows 52 with the upper side of the plug. A loop 68 to receive a lifting hook 75 is secured to the cap 43, and disengagement of the hook is prevented by the upstanding arm 73 of a weighted bell-crank lever 69 ; a pin 76 extending from the top of the rod 58 engages the arm 74 of the lever to tilt the lever and release the hook. Rotation of the plunger 44 is prevented by a stud 77. To readily test for the leakage of gases past the packings between the plug 19 and pipe 11, a groove 79 is provided between the packing rings 23, 25, and a groove 81 is formed between the packing rings 56 the grooves being connected by pipes 82 connected to adaptors 84 normally sealed by plugs 86 but to which can be connected pressure gauges. When the plug is to be inserted into the pipe 11 the plunger 44, Fig. 4, is supported by the sleeve 39 and the balls are free to move radially inwardly, the bellows 52 are extended and the rod 58 is in the downward position thereof relative to the stem 38 so that the balls 64 move clear of the groove 65. The plug is lowered until the shoulder 21 rests on the surface 17 of the pipe 11, and the plunger 44 moves downwardly so that the cam surface 46 thereof urges the balls 22 outwardly into the groove 18 and the shoulder is pressed firmly on to the surface 17. If gas is drawn off from above the plug the pressure in the pipe causes the bellows 52 to contract thereby raising the rod which cams the balls 64 into the groove 65 and so lock the sleeve 39 against upward movement, and lock the plug against release. In a modification the plug is arranged for insertion upwardly into a downwardly opening stack pipe. In a further modification, the plug has a central opening and comprises a body 125, Fig. 6, formed with a flange 126 to which is secured a sleeve 127, a ring 128 attached to the body to provide a second flange, and a sleeve 129 to form the inner wall of an annular cavity 103. Slidably mounted on the sleeve 127 is a plunger 133 urged downwardly by springs 134, and balls 135 located in holes 136 in the body 125 cooperate with a cam surface 141 of the plunger. The latter has an extension 142 apertured for balls 144 which co-operate with a circumferential groove 145 in the sleeve 127. A ring 146 has a camming surface 147 to push the balls 145 inwardly when the ring is moved upwardly, and the ring carries a number of posts 148 the lower ends of which are fixed to bellows 151 arranged in the cavity 130. In a still further modification, the plug is provided with a central passage formed by a tubular stem 177, Fig. 10, slidable on which is a plunger 179 having a disc-like upper portion 181 and a sleeve-like lower portion 182, a flexible bellows 184 being secured to the top of the stem and to the lower end of a tube 185 welded at the upper end thereof to the plunger. The portion 181 of the plunger has a camming surface 187 for urging outwards balls 173 located in holes 172 in the plug body 165. A sleeve 189, slidable on the portion 182 has a flange 191 to the underside of which is secured the end plates 192 of a number of bellows 193, the lower ends of the bellows being attached to end plates 194 integral with a tubular stem 195 providing communication between the interiors of the bellows and the underside of the plug ; the sleeve has a frusto-conical shoulder 198 and the portion 182 of the plunger 179 is formed with radial holes 199 in which are mounted balls 201 co-operable with a circumferential groove 202 in the stem 177. Additional, passages 204 through the plug are formed by tubes 205, 206 secured in the body 165 and portion 181 of the plunger 179, the tubes being connected to each other by a flexible bellows 207. To provide for visual indication of the position of the sleeve 189, a rod 217 is caused to project radially from the periphery of the plug.