GB2109725A

GB2109725A - Apparatus for explosively joining tubes

Info

Publication number: GB2109725A
Application number: GB08233920A
Authority: GB
Inventors: John Anthony Regalbuto; James Elvin Dailey
Original assignee: Brown and Root Inc; Jet Research Center Inc
Current assignee: Brown and Root Inc; Jet Research Center Inc
Priority date: 1979-08-16
Filing date: 1982-11-29
Publication date: 1983-06-08
Also published as: GB2057320B; AR230332A1; GB2057320A; NL8004179A; GB2109725B; CA1175645A

Description

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GB 2 109 725 A 1

SPECIFICATION

Apparatus for explosively joining tubes

The present invention is concerned with apparatus for explosively forming at least one 5 circumferential joint between two tubular members disposed one within the other, this apparatus being particularly useful in the construction of marine structures.

Generally, a marine structure used for the 10 exploration and production of hydrocarbons comprises an underwater portion, comprising a jacket which is fabricated as a framework of tubular members, a plurality of piles driven into the sea bed, and a deck section set on top of the 15 jacket after the piles have been secured to the jacket.

In such a marine structure, the jacket serves as a template or guide through which the piles are driven into the sea bed and then, after the piles 20 have been driven and secured to the jacket, the jacket provides a strong framework to transmit and distribute loads imposed on the structure as a whole to the piles.

In shallow water, main piles driven through the 25 jacket legs are normally sufficient to provide adequate support for such a marine structure, the main piles being generally connected to the jacket at the top of each jacket leg by welding the pile to the jacket leg before the desk section is set 30 thereon. As the water depth increases, a point is reached where the main piles in the jacket legs are no longer sufficient by themselves to withstand the increasing horizontal shear forces and overturning moments imposed on the structure. 35 Additional support for the marine structure is then required which is usually provided in the form of skirt piles arranged about the base of the structure.

Rather than extending to the top of the jacket, 40 skirt piles are usually truncated at some distance above the sea bed for two primary reasons. First, the skirt piles are not needed for structural integrity of the jacket and, second, additional members, such as skirt piles, extending to the top 45 of the jacket into the wave zone of the jacket would attract more wave forces, thereby increasing the stresses in adjacent members.

Since the connection between the skirt around the jacket and the pile to the skirt is made 50 underwater, the procedures used to make the pile to skirt connection are an important consideration in the design of the marine structure.

Various methods of explosively connecting the skirt piles to the jacket skirt have been proposed, 55 as described in detail in U.K. Patent Application 802643S (Specification No. 2057320) from which the present application has been divided.

According to the present invention, there is provided improved apparatus for explosively 60 forming at least one circumferential joint between two tubular members disposed one within the other, which comprises an elongate member having thereon at least one annular carrier, the or each said carrier being constructed and arranged to carry an annular explosive charge for insertion into and movement along the inner tubular member, and means for centralising the or each annular carrier in the inner tubular member, both in the respective operative position for explosive forming and during movement along the inner tubular member.

The annular carrier in the apparatus according to the invention can be readily removed from the inner tubular member prior to detonation of the explosive charge, if a malfunction occurs.

In the following description, reference will be made to the accompanying drawings, in which:

Figure 1 is a view of an illustrative marine structure;

Figure 2 is a section of part of Figure 1, at a predetermined location at which a circumferential joint is to be explosively formed;

Figure 3 is a cross-section of the arrangement of Figure 2, taken along the line 3—3;

Figure 3A is an enlarged sectional view of part of Figure 3, taken along the line 3A—3A;

Figure 4 is similar to Figure 2, showing the tubular members after they have been explosively joined; and

Figure 5 is a section of a modification of the arrangement shown in Figure 2.

Referring to Figure 1, a marine structure 10 is shown. The marine structure 10 comprises a jacket 1 having skirt pile sleeves 2 thereon, piles 3 driven through the jacket into the sea bed, and a deck 4 above the surface of the body of water in which the marine structure 10 is installed.

The jacket 1 comprises a plurality of jacket legs 5, each having a pile 3 driven therethrough into the sea bed interconnected by a plurality of horizontal braces 6 which are also interconnected by a plurality of angular braces 7.

The skirt pile sleeves 2 comprise tubular members secured to the jacket 1 by means of a horizontal brace 6 and angular braces 7. The skirt pile sleeves 2 each have a pile 3 driven therethrough into the sea bed.

The deck 4 is secured to the tops 8 of the jacket legs 5, by welding, for example, to form the marine structure.

Referring to Figure 2, there is shown a skirt pile sleeve 2 having a pile 3 driven therethrough of the marine structure 10, a tubular member or can 11, explosive carrier member 12, seal means 13 and inlet port 13'.

As shown, the tubular member or can 11 comprises a heavy walled or thick tubular member 14 having an inlet port 1 5 in the upper portion thereof, a circumferential annular groove or socket 16 in the interior therof, and an outlet port 17 in the lower portion thereof.

The tubular member 11 further contains a seal 13 on the interior surface thereof to sealingly engage the pile 3 driven therethrough. The seal 13 may be any commercially available seal capable of forming a reliable seal with the pile 3 after the pile 3 has been driven therethrough. The seal 13 may, alternatively, be located above the tubular member 11 at any convenient location. Examples

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of suitable seals 13 which may be utilized are described in U.S. Patents 3,468,132 and 4,047,391.

The tubular member 11 may be secured at any 5 point in either the jacket legs 5 or skirt pile sleeves 2, although it is preferred that they be installed at the intersection of the horizontal 6 and angular 7 braces with the jacket legs 5 and skirt pile sleeves 2.

10 Also shown in Figure 2, located on either side of the tubular member 11, are centralizer means 18 which are used to centre the pile 3 in the skirt pile sleeve 2.

The explosive carrier member 12 as shown in 15 Figure 2 comprises a carrier body 21 having an annular explosive charge 20 secured thereto, within arcuate annular channel members 22 which are, in turn, secured to outer annular carrier 22' of carrier body 21. The outer annular carrier 20 2.2' is retained on central mandrel 24 of the carrier body 21 by means of struts 23. The struts 23 may ba of any convenient cross-sectional shape and of any type material sufficient to support the explosive charge 20.

25 Typically, the explosive charge 20 is toroidal or annular in configuration and is installed on the explosive carrier member 12 by attaching means 25.

The explosive carrier member 12 further 30 comprises centralizer means 26 located on either side of the explosive charge 20. The centralizer means 26 may be of any convenient type,

although a plurality of radial struts 27 connected to a central elongate member 28 having wheels 35 29 thereon are preferred (see also Figure 3).

The centralizer means 26 may be secured to the central mandrel 24 of the explosive charge carrier 21 by any convenient easily releasable means, such as a threaded coupling 30. 40 The explosive carrier member 12 additionally comprises plug and lifting means 30' and 31 respectively to provide a means by which a line 100 can be attached to the explosive carrier member 12 to position the explosive carrier 45 member in a jacket leg 5 or skirt pile sleeve 2.

Also included on the explosive carrier member 12 (not shown in Figure 2) is an indicator means, such as a commerically available ultrasonic indicator for indicating the position of the 50 explosive charge carrier member 12 within the pile 3 (the correct operative position being substantially centered about the annular groove 16 in the tubular member 11), and a detonator having suitable actuation means to initiate 55 explosion of the explosive charge 20.

Referring to Figure 3, the centralizer means 26 is shown in more detail; the centralizer means 26 comprises a plurality of radial struts 27 secured to a central elongate member 28 and interconnected 60 about their outer ends by braces 32.

Referring to Figure 3A, the details of the wheels 29 and their interconnection with the centralizer means 26 can be seen. Each wheel 29 is retained on a U-shaped member 33 by a threaded bolt 34 65 having nuts 35 thereon. The U-shaped member 33 is secured to a rod 36 by a pin 37. The rod 36, in turn, passes through bore 38 in the end 39 of strut 27 and has a plate 40 having spring actuated pin 41, actuated by spring 42. The plate 40 on rod 36 70 is biased outwardly by a compression spring 43, which is retained within strut 27 and has one end thereof bearing against strut plug 44 while the other end bears against plate 40. To prevent the wheel 29 from rotating about the axis of rod 36 75 when the centralizer means 26 engages the inner surface of the skirt pile sleeve 2 or jacket leg 5, the pin 41 engages a slot 45 in strut 26 and slides therein.

When the centralizer means 26 engages the 80 inner surface of the skirt pile sleeve 2 or jacket leg 5 when the explosive carrier member 12 is being lowered therein, the wheels 29 of the centralizer means 26 are biased into engagement with the skirt pile sleeve 2 or jacket leg 5 by compression 85 spring 43.

Arrangements other than the illustrated centralizer means 26 may be used to centre the explosive charge carrier 21 in the skirt pile sleeve 2 or jacket leg 5, if desired.

90 Referring again to Figure 2, the procedure for determining the various relationships between the tubular member 11, explosive carrier member 12 and the pile 3 is discussed in detail in ihe above mentioned Patent Application 8026439. 95 The operation of the apparatus according to the invention is also described in the above-mentioned Patent Application 8026439.

Referring to Figure 5, there is shown apparatus according to the invention with two annular 100 carriers 22'. (Like numerals in Figure 5 denote like parts to those shown in Figure 2.) By means of the apparatus of Figure 5, three circumferential joints can be made between tubular member 14 and pile 3, as described in detail in the above-105 mentioned Patent Application 8026439.

Claims

1. Apparatus for explosively forming at least one circumferential joint between two tubular members disposed one within the other, which

110 comprises an elongate member having thereon at least one annular carrier, the or each said carrier being constructed and arranged to carry an annular explosive charge for insertion into and movement along the innner tubular member, and 115 means for centralizing the or each annular carrier in the inner tubular member, both in the respective operative position for explosive forming and during movement along the inner tubular member.

2. Apparatus according to claim 1, in which the 120 or each annular carrier is connected to the elongate member by a plurality of struts.

3. Apparatus according to claim 1 or 2, which also comprises a detonator on the or each annular carrier.

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4. Apparatus according to any of claims 1 to 3,

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which further comprises means for indicating the

5. Apparatus according to claim 1, substantially position of the or each annular carrier in the inner 5 as described herein with reference to the tubular member. accompanying drawings.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1983. Published by the Patent Office 25 Southampton Buildings, London, WC2A 1AY, from which copies may be obtained.