GB2178506A - Pipeline - Google Patents

Abstract

A pipe has a protective and/or insulating coating which has a longitudinal recess for receiving a cable or flow line thereby allowing the cable and/or flow line to be contained within the wall of the coated pipe. <IMAGE>

Description

SPECIFICATION Pipeline This invention relates to a pipeline, especially but not exclusively for use in an underwater environment.

In the offshore oil industry pipelines are provided for transporting oil from the well to a remote location, and such pipelines are generally coated with protective material, for example heatinsulating, corrosion-resistant or abrasion-resistant material, or a combination of these. In addition, cables and flow lines may be required to run alongside the pipeline, and these can become damaged unless otherwise protected.

According to the present invention there is provided a pipe having protective and/or insulating material on its outer face, wherein said material has a recess extending from one end of the pipe to the other for receiving a cable and/or flow line.

The recess is preferably in the form of a groove of a depth at least as great as the cable or flow line which it is to receive. The recess may extend longitudinally or helically of the pipe, and in the latter case undue cable stresses in a pipeline constructed of pipes of the invention are reduced.

The recess can be provided in an insulating coating around the pipe, or in a corrosion- or abrasion-resistant coating or layer. The recess may have an opening of a width less than the width of the main portion of the recess, so that the cable "snaps in" to the recess and is retained therein.

In forming a pipeline from pipes of this invention the recesses in adjacent pipes may be aligned so that the direction of the cable is uniform.

The recess may be of any dimensions commensurate with receiving the cable or flow line, for example from 0.5 cm to 4 cm in width.

The recess may be formed in a pipe coat which is applied to the pipe in a mould, and the recess can be provided by placing an additional key in the mould, most preferably longitudinallymovable in the mould, so that it can be withdrawn after setting of the material in the mould.

Alternatively the recess may be formed after coating is completed, by cutting a groove as required.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figures 1 and 2 are side views of alternative pipes of the invention; and Figure 3 is an end view of the pipe of Fig. 1.

Referring to the drawing, the pipeline of these embodiments of the invention each have a steel pipe 1 for carrying oil, the pipe to be laid in use on the sea bed. If the pipe 1 were not protected from corrosion it would rust, with eventual failure of the pipe wall, so a corrosionresistant sealing layer 2 is applied to the pipe 1 so as to envelope completely the pipe outer face.

The layer 2 consists of 6 mm thick polychloroprene rubber which is sold under the Trade Mark LINECOTE and is a flexible elastomer which is vulcanised and bonded to the pipe 1. The layer 2 provides a tough coating which is highly chemical and temperature resistant and impervious to moisture and sea water. It is also resistant to abrasion and has high tear and tensile strength, is highly resistant to ozone attack and flex cracking and has low temperature flexibility down to minus 30 degrees centigrade. It is resistant to oils, waxes and gases and most aliphatic hydrocarbons.

Around the corrosion-resistant layer 2 is a jacket 3 which provides both heat insulation and protection against mechanical damage.

The jacket 3 has a groove 4 formed in its outer face extending along the length of the jacket.

In Fig. 1 the groove 4 is axially-directed while in Fig. 2 it is helical. As can be seen in Fig. 3, the groove 4 has a relatively wide body portion 4A and a relatively narrow neck 4B so that an elongate member such as an electrical or fibre-optic cable or a hydraulic flow line can pass along the body portion 4A and be retained therein by virtue of the narrow neck 4B. The material of the jacket 3 is sufficiently flexible to allow the elongate member to be snapped into the groove through the neck 4B.

The jacket 3 consists of polyurethane which is 50 mm thick and which is based on a two-part polyurethane system having high abrasion and cut growth resistance, and excellent resistance to sea water. The physical properties of the material are as follows: Hardness (IRHD) 84 Tensile strength (psi) min. 1850 Elongation at Break (%) min. 350 Tear Resistance (Ib/inch) min. 200 Specific Gravity 1.13 Taber Abrasion Resistance Loss/1000 cycles (mg) 100 Compression Set at 70 degrees centigrade 40 Volume Swell in Sea Water Typical % Change Temperature 1 Week 2 Weeks 3 Weeks 4 degrees centigrade 5.16 6.10 6.44 38 degrees centigrade 3.19 3.50 3.08 70 degrees centigrade 3.74 3.74 3.32 The insulated pipeline of this embodiment of the invention is manufactured by rotationally extruding the LINECOTE polychloroprene rubber onto the cleaned outer face of the pipe 1 to provide the layer 2. The rubber is applied in a manner which ensures that the pipe outer face is completely covered by the layer 2 thereby to protect it totally from its environment.

The outer face of the pipe 1 is pre-cleaned and prepared for coating by shotblasting to a minimum SA 2.5 and applying a primer under controlled temperature and humidity conditions.

After vulcanising the polychloroprene rubber in a steam autoclave at 153 degrees centigrade and 60 psi a 100% rubber tear bond is obtained (i.e. the strength of the chemical bond is greater than the tensile and tear strength of the rubber).

The jacket 3 is applied to the outer face of the corrosion-resistant layer 2 by first forming a mould (not shown) around the coated pipe 1 which defines a space between the layer 2 and the mould corresponding to the intended volume and shape of the jacket 3, and then inserting into the mould a longitudinally-movable key of complementary profile to the groove 4. Polyurethane to form the jacket 3 is then injected from a two-part polyurethane mixing machine into the mould and allowed to cure to form the flexible, non-cellular jacket 3. The key is then withdrawn through the end of the mould, and the mould is opened, leaving the insulated pipeline in the form shown in the drawing.

The groove 4 allows operators to assemble pipes of these embodiments on site by welding together, and in so doing the pipes are aligned to ensure that the ends of the grooves 4 of adjacent pipes are opposed. Cables and/or flow lines can then be snapped into the grooves 4 to be retained therein, and the assembled pipeline then placed on the sea bed.

The embodiment of Fig. 2 allows the pipeline to be laid from a reel barge without causing differential stress to the cables and/or flow lines.

Any number of grooves can be provided along each pipe in accordance with requirements.

Modifications and improvements may be made without departing from the scope of the invention.

Claims (1)

1. A pipe having protective and/or insulating material on its outer face, wherein said material has a recess extending from one end of the nine to the other for receiving a cable and/or flow line.

2. A pipe according to Claim 1, wherein the recess extends longitudinally of the pipe along an axis parallel to the axis of the pipe.

3. A pipe according to Claim 1, wherein the recess has a relatively wide body portion for receiving said cable and/or flow line and a relatively narrow neck portion through which said cable and/or flow line can pass into the body portion.

5. A pipe according to any one of the preceding Claims, wherein the protective and/or insulating material is elastomeric.

6. A pipe according to any one of the preceding Claims, wherein the recess is from 0.5 to 4 cm in width.

7. A pipe according to any one of the preceding Claims, having a cable or flow line extending along it within the recess.

8. A pipe according to Claim 1, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

9. A pipeline comprising interconnected pipes according to any one of the preceding Claims, each pipe being aligned with adjacent pipes so that their recesses communicate with each other.