GB1467230A - Bolt tensioning apparatus - Google Patents

Abstract

1467230 Bolt tensioning apparatus BRITISH PETROLEUM CO Ltd 16 Jan 1975 [17 Oct 1973] 48383/73 Heading F2H Bolt tensioning apparatus, see Fig. 1, suitable for use in underwater locations comprises a sleeve 1 having an end surface provided with seals 16 which engage a flange 11, a blind nut 12 which engages bolt 4, the sleeve and nut forming a fluid-tight enclosure about the end of the bolt and nut 5, a shaft 22 having an outer end 34 rotatable by a spanner and an inner end provided with a toothed ring 18 engageable with a toothed ring 6, 7 on nut 5, the arrangement being such that on introduction of hydraulic fluid into the fluid-tight enclosure via inlet 19 and channel 35 the bolt is tensioned. The shaft 22 may be provided with an annular piston 21 and a thrust pad 25 may be interposed between the shaft and nut 5 to prevent binding. In use, nuts 5 and 12 are run on to bolt 4, the sleeve being installed either before or after nut 12. Ring nut 13 is then rotated by lugs 15 to set seals 16 against flange 11. When hydraulic fluid is introduced via inlet 19, it acts on area 20 of the sleeve forcing the latter against the flange, and also enters channel 8 and groove 9 in nut 5 to effect pressure balancing. Simultaneously, hydraulic fluid acts on piston 21 via channel 23 in blind nut 12 to force the shaft towards nut 5 so that the toothed rings 6, 18 are in engagement. The fluid also acts on the blind nut thereby tensioning the bolt. End 34 of shaft 22 may then be rotated to run nut 5 up against flange 11. In a modification, see Fig. 2, nut C bearing against the flange is provided with a recess in which is enclosed a seal ring A loaded by a Belleville spring B. Studs as well as bolts may be tensioned in the manner indicated.