GB2506840A

GB2506840A - Demountable pile stopper or cap with conical ring

Info

Publication number: GB2506840A
Application number: GB201214377A
Authority: GB
Inventors: David Aviram; Stephen Stuart-Matthews; Wangwen Zhao
Original assignee: Offshore Design Engineering Ltd
Current assignee: Offshore Design Engineering Ltd
Priority date: 2012-08-13
Filing date: 2012-08-13
Publication date: 2014-04-16
Also published as: GB201214377D0

Abstract

A demountable pile stopper or cap includes a pile head 3, a leg conical ring 2a, collets 8, 8a, retaining rings 4, (4a, figure 3), and an elastic pad 6. The leg conical ring bears upon the conical face of the collet, the collet being held in place by the retaining ring thereby enabling load transfer to the elastic pads of the collet, which bear upon a flange of the pile head. The pile stopper may be used with an offshore foundation structure for transferring loads from a foundation leg via a collet and elastic pads onto a flange of the pile. The retaining ring may be joined by a hinge bolt 7 and lock bolts (4b, figure 3).

Description

Demountable Pile Stopper The invention relates to a device for demounting temporary supports of off-shore jacket legs from supporting piles.

Off-shore support structures consist of jacket legs that are anchored by means of grout to piles that are embedded in the sea bed. The jacket provides structural support for the super-structure and must be levelled and aligned.

Current methods for initial alignment of jacket legs consist of a set of elastomeric rubber pads that are connected to a leg flange, and which bear upon opposing pile flange which forms part of a pile end cap. The pads provide a temporary means of load transfer from leg to pile, while Is alignment of the structure takes place. Once the structure has been aligned, the cavity between leg and pile is filled with grout. When set, the grout provides a load path between leg and pile and the elastomeric piles become redundant. At such time, the elastomeric pads must be unloaded in order to prevent structural damage to the leg during the lifetime of the structure. Currently, removal of the temporary pads can only be achieved by destructive means, due to the compressive loads on the pads.

Another constraint for levelling of jacket structures arises from fine limits on vertical alignment of wind turbine support towers. At present, such fine levelling is made by means of complex measurements and use of specially manufactured sets of shims, which are place at main structural supports.

It is an aim of the present invention to provide a solution of a type that is not made in a conventional manner and that will overcome the limitations mentioned above.

An alternative solution for pad removal from leg attachments and fine levelling of the support structure are the main aims of this invention.

Accordingly, this invention provides for a demountable Pile Stopper assembly, characterized in that at least two sets of opposite and adjacent bearing parts of a leg and pile assembly have inclined mating surfaces that provide a load path between the opposing structural entities and that they are contained by means of an annular retainment ring. The retainment ring may also be used for fine vertical adjustment by means of gradual opening. When grout connecting the pile and leg is cured, the ring may be dismantled and the Pile Stopper assembly removed.

io The Pile Stopper has at least one flat bearing surface on one side of one set of inclined surfaces for housing a set of compressible pads, which, in turn, bear upon an opposite bearing surface of the opposing structural entity. When the retainment ring is released, the stored compressive energy within the pads will assist with demounting the retainment ring.

In one preferred embodiment of the Demountable Pile Stopper, an annular conical ring is welded along a leg section, opposite a corresponding pile end-cap. A series of conical steel collets are situated opposite the conical ring and are retained in place by means of a containment ring. The ring may be split by means of a conventional hinge and lock. The collets lower surfaces have a series of elastomeric rubber pads that engage with the flange of the pile end cap. The leg extends within the pile for providing a contact surface for grouting when load transfer via the elastomeric pads is no longer required.

The pile end cap consists of an annular flat flange that provides a bearing surface for the elastomeric rubber pads.

Such application may be found in the oil and gas industry, where use of subsea oil installations is prevalent.

One embodiment of the invention will be described solely by way of example and with reference to the accompanying drawings in which: Fig. 1 shows a general external view of a Demountable Pile Stopper assembly with retainment ring in the closed position; Fig. 2 shows a general external view of a Demountable Pile Stopper assembly with retainment ring in the closed position; Fig. 3 shows a cross section of a Dernountable Pile Stopper assembly; io Fig. 1 shows a Demountable Pile Stopper assembly with the retainment ring in the locked position. The assembly consists of pile (1) with leg (2) protruding within and retainment ring assembly (5 & 6) in the locked position by means of bolts (4b). The pile head has a flanged upper surface (3) for load transfer from the leg (1). The leg (2) has Is castellated conical ring (2b) which serves for transfer of lateral and shear loads. Pile (1) has grout filling port (la) for affecting a shear key between leg (2) and pile (1) Fig. 2 shows a Deniountable Pile Stopper assembly with the retainment ring in the open position. The collets (8 & 8a) transfer loads from the conical ring (2a), when in the closed position, via elastic pads (6) onto pile head upper flange (3).

Fig.3 shows a sectional view of a Demountable Pile Stopper assembly.

The leg (2) transfers loads via welded castellated ring (2b) to conical ring (2a) which bears upon collets (8 &8a) on pads (6) and unto pile head flange (3). Retainment rings (4 & 4a) prevent the collets (8 &Sa) from radial movement, thereby ensuring axial load transfer to pads (6). Compressive energy in pads (6) will assist in opening retaining rings (4 &4a), when bolts (4b) are released and rotate about hinge bolt (7). Pile (1) is equipped with grout charging port (la) for affecting a grout connection between pile (1) and leg (2) which has welded bead shear keys (2c).

Claims

Claims 1. Demountable File Stopper set consisting of at least one pile head (3), one leg conical ring (2a), collets (8 &8a), retainment rings (4 &4a) and elastic pads (6) characterised in that the leg conical ring (2a) bears upon collets conical faces (8 & 8a), which are held in place by retainment rings (4 & 4a) thereby enabling load transfer to collets elastic pads (6) which bear upon pile head flange (3).
2. Demountable Pile Stopper set according to claim 1 characterised in that the retainment rings (4&4a) are joined by a hinge bolt (7) and lock bolts (4b).
3. Demountable Pile Stopper set according to claims 1 &2 characterised in that the elastic pads (6) assist the release of the retainment rings (4 &4a) when lock bolts (4b) are undone and the leg (2) is secured to the pile (1) by means of grout in the void between leg (2) and pile (1).
4. Demountable Pile Stopper set according to claims 1 to 3 characterised in that the retainment ring lock bolts (4b) may be used for leg (2) height adjustment, by means of gradual tightening or release of bolts (4b), before the leg (2) and pile (1) are bonded by means of grout in the cavity between leg (1) and pile (2).