Improvements in or relating to Water Suction Hoses

The present invention relates to a hose section, particularly, but not exclusively, to a hose section for a sea water suction hose system and a method of assembling a sea water suction hose.

Conventional sea water suction hose systems such as those installed on Floating Production Storage and Offloading (FPSO) vessels typically comprise a plurality of hoses and caissons. Each hose typically comprises of a plurality of hose sections interconnected to form a continuous hose. The continuous hose combines with a caisson on the FPSO to form the sea water suction system.

The free end of the hose is fitted with a suction strainer for straining sea water which is drawn into the hose. The suction strainer is fitted with a hypochlorite dispersion ring which is used to disperse hypochlorite around the suction strainer as sea water is drawn through the hose. The dispersion of hypochlorite prevents marine growth in the suction hose system and associated pipework of the FPSO.

In order to supply hypochlorite to the dispersion ring it is necessary to provide a hypochlorite supply line within the hose. The hypochlorite supply line comprises a plurality of line sections.

In order to prevent the hypochlorite supply line from breaking, each line section is required to be secured within the hose. This is achieved by providing a plurality of hose adaptors between each hose section. Each hose adaptor provides an internal mount for securing each hypochlorite line section thereto.

Installing a hose adaptor between each hose section is costly and increases the assembly time of the hose. Furthermore, the presence of a hose adaptor between each hose section increases the potential for corrosion and the number of potential leakage points in the hose.

It is an object of the present invention to provide a hose section for a sea water suction hose system and a method of assembling a sea water suction hose which obviates or mitigates one or more of the disadvantages referred to above.

According to a first aspect of the present invention there is provided a hose section for a sea water suction hose comprising attachment means for attaching an auxiliary hose section thereto.

Preferably, the attachment means is internally mounted to the hose section. Alternatively, the attachment means is externally mounted to the hose section.

Preferably, the attachment means is positioned adjacent an end of the hose section.

Preferably, the attachment means is positioned at the nipple of the hose section.

Preferably, the attachment means is welded to the hose section.

Preferably, the attachment means includes at least one fixing hole for attaching the auxiliary hose section thereto.

Preferably, the attachment means has a protective coating.

Preferably, the protective coating is resilient.

Preferably, the protective coating is rubber.

Preferably, the hose section comprises two attachment means.

Preferably, the attachment means are located at either end of the hose section.

Preferably, the hose section comprises a plurality of attachment means.

Preferably, the attachment means are configured to secure a hypochlorite hose section to the hose section.

Preferably, the hose section further comprises connecting means at either end thereof.

Preferably, the connecting means have a protecting coating. More preferably, the coating is resilient. More preferably still, the coating is rubber.

Preferably, the connecting means are flanges.

Preferably, the hose section is flexible.

According to a second aspect of the present invention there is provided a sea water suction hose comprising at least two hose sections according to the first aspect of the present invention.

Preferably, the hose further comprises at least two auxiliary hose sections secured to the attachment means of the hose sections.

Preferably, the auxiliary hose sections are hypochlorite supply hoses.

According to a third aspect of the present invention there is provided a sea water suction hose comprising: at least one hose section according to the first aspect of the invention; a suction hose head connected to one end of the hose section; and a suction strainer connected to the other end of the hose section.

Preferably, the sea water suction hose further comprises at least one auxiliary hose section secured to the attachment means of the hose section.

Preferably, the auxiliary hose section is also secured to the suction strainer and the suction hose head.

Preferably, the auxiliary hose section is a hypochlorite supply hose.

Preferably, the sea water suction hose comprises a plurality of hose sections.

Preferably, the sea water suction hose comprises a plurality of auxiliary hose sections.

According to a fourth aspect of the present invention, there is provided a sea water suction hose system comprising:

at least one caisson; and at least one sea water suction hose according to the third aspect of the present invention, wherein the caisson is configured to receive and hold the hose in suspension.

Preferably, the sea water suction hose system further comprises a caisson interface between the caisson and the sea water suction hose.

Preferably, the sea water suction hose system is configured to be attached to an FPSO vessel.

Preferably, the sea water suction hose system is configured to be formed within the hull of an FPSO vessel.

According to a fifth aspect of the present invention there is provided a FPSO vessel comprising a sea water suction hose system according to the fourth aspect of the present invention.

According to a sixth aspect of the present invention there is provided a method of assembling a sea water suction hose comprising the steps of: providing at least two sea water hose sections each having an attachment means for attaching an auxiliary hose section thereto; attaching an auxiliary hose section to each sea water hose section; connecting the auxiliary hose sections together; and connecting the sea water hose sections together.

Preferably, the auxiliary hose sections are hypochlorite supply hoses.

According to a seventh aspect of the present invention there is provided a method of assembling a sea water suction hose comprising the steps of:

providing at least one sea water hose section having an attachment means for attaching an auxiliary hose section thereto; attaching an auxiliary hose section to the sea water hose section; connecting a suction hose head to one end of the sea water hose section; connecting a suction strainer to the other end of the sea water hose section; and connecting the auxiliary hose section to the suction strainer and the suction hose head.

Preferably, the auxiliary hose section is a hypochlorite supply hose.

An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:-

Figure 1 is a side view of a hose section for a sea water suction hose in accordance with the first aspect of the present invention;

Figure 2 is a cross-sectional side view of the hose section of Figure 1 ;

Figure 2a is a partial end view of the hose section of Figures 1 and 2, detailing the attachment means;

Figure 3 is a side view of a suction strainer which is used with the hose section of Figure 1 ;

Figure 4 is a cross-sectional side view of the suction strainer of Figure 3;

Figure 5 is a side view of a suction hose head which is used with the hose section of Figure 1 ;

Figure 6 is a cross-sectional side view of the suction hose head of Figure 5;

Figure 7 is a cross-sectional partial side view of a caisson interface installed within a caisson in the hull of an FPSO;

Figure 8 is a side view of a sea water suction hose system in accordance with the fourth aspect of the present invention; and

Figure 9 is a cross-sectional side view of the sea water suction hose system of Figure 8.

Figures 1 and 2 illustrate a hose section 10 for a sea water suction hose. The hose section has a cylindrical body 12 with flanges 14 located at either end thereof (flanges 14 being an example of connecting means).

With reference to Figures 2 and 2a, the hose section 10 further comprises an attachment means 18 for attaching a hypochlorite hose section 20 thereto (a hypochlorite hose section being an example of an auxiliary hose section).

The attachment means 18 is welded to the internal surface of the hose section 10 adjacent the hose section nipple (not referenced). The attachment means 18 includes at least one fixing hole 22 which is used to secure the hypochlorite hose section 20 thereto.

The hose section 10 and the hypochlorite hose section 20 are flexible and include tensile reinforcement to reduce weight, increase corrosion resistance and proved excellent fatigue properties.

The attachment means 18 and the flanges 14 have a protective coating to prevent corrosion. The protective coating is a resilient material, e.g. rubber.

Figures 3 and 4 illustrate a suction strainer 24 for use with the hose section 10. The suction strainer 24 strains sea water which is drawn through the hose section 10. The suction strainer is generally cylindrical in shape and is fitted with a hypochlorite dispersion assembly 26 which is used to disperse hypochlorite around the suction strainer 24. The dispersion of hypochlorite prevents marine growth in the suction hose system and associated pipework of the FPSO. The suction strainer 24 also includes a flange 28 which is used to connect the strainer 24 to the hose section 10.

Figures 5 and 6 illustrate a suction hose head 30 which is used with the hose section 10. The suction hose head 30 provides the interface between the hose section 10 and a caisson of a sea water suction hose system. The head 30 includes a male conical seat 32 which mates with a female conical seat of a caisson interface, preventing downward movement of the suction hose (see below).

To prevent tilting, the head 30 includes an external upper circumferential bearing ring 34 which mates with a caisson interface internal circumferential bearing ring (see below).

The head 30 also includes a flange 36 which is used to connect a hose section 10 thereto. The head 30 also includes a hypochlorite hose assembly 38. There is also provided engagement means 40 for engaging a deployment/retrieval tool therein (see below).

Figure 7 illustrates a cross-sectional partial side view of a caisson interface 42 installed within a caisson 44 in the hull of an FPSO. The caisson interface 42 includes a female conical seat 46 which mates with the male conical seat 32 of the suction hose head 30 to centralise the head 30. The caisson interface 42 also includes an internal circumferential bearing ring 48 which mates with the external upper circumferential bearing ring 34 of the suction hose head 30.

Figures 8 and 9 illustrate an assembled sea water hose 50 held in suspension from the caisson interface 42 of the caisson 44 of an FPSO. The hose 50 comprises a plurality of hose sections 10, a suction strainer 24 and a suction hose head 30. The sea water hose 50 and the caisson 44 form a sea water suction hose system.

The assembly of the sea water hose 50 is carried out in a conventional manner, i.e. by suspending each hose section 10 at the top of the caisson 44 whilst each subsequent hose section 10 is attached thereto. The hose sections 10 are bolted together at the flanges 14.

In the present invention, a hypochlorite hose section 20 is attached to the attachment means 18 of each hose section 10 prior to assembly of the hose sections 10. During assembly, the hypochlorite hose section 20 of a lower hose section 10 is firstly connected to they hypochlorite hose section 20 of an upper hose section 10 prior to connection of the upper and lower hose sections 10. The result is that a continuous hypochlorite hose extends the entire length of the assembled hose 50. In order to make the connection of the hose sections 10 safer, there may be provided a safety collar (not shown) which is connected to a lower hose section 10 whilst the hypochlorite hose sections 20 of the lower and upper hose sections 10 are

being connected together. Once the hypochlorite hose sections 20 have been connected, the safety collar is removed and the hose sections 10 bolted together, as described above.

Of course, the suction strainer 24 is connected to the lower free end of the first hose section 10 prior to insertion in the caisson 44. The hypochlorite hose section 20 in the first hose section 10 is connected to the hypochlorite dispersion assembly 26 of the strainer 24 prior to the strainer 24 being bolted to the hose section 10.

The suction hose head 30 is connected to the last upper hose section 10. The hypochlorite hose section 20 in the last hose section 10 is connected to the hypochlorite hose assembly 38 of the head 30 prior to the head being bolted to the hose section 10.

The sea water hose 50 may be lowered in and out of the caisson 44 in a conventional manner by a deployment/retrieval tool (not shown).

The sea water hose 50 is disassembled in a conventional manner, i.e. by lifting the hose 50 toward the top of the caisson 44 and reversing the assembly steps described above.

The hose section 10 therefore obviates or mitigates the disadvantages of previous proposals by proving an attachment means 18 for attaching an auxiliary hose section 20 thereto. Providing a hose section 10 including an attachment means 18 removes the requirement for a hose adaptor to be provided between each hose section of a sea water suction hose to support the hypochlorite supply line.

A sea water suction hose 50 comprising a plurality of hose sections 10 has an increased field life, increased reliability and makes the assembly of the hose 50 simpler. By eliminating the hose adaptors:

• The number of sub-sea steel components exposed to sea water is significantly reduced, thus reducing cost and minimising the potential for corrosion.

• There is no risk in damaging any protective coating applied to the hose adaptors during installation. As the assembly through the caisson is "blind" the damage to the protective coating is not identified until there is an inspection or failure of the hose.

• The level of cathodic protection is reduced.

• The number of flanged joints is significantly reduced, thus minimising potential leakage points. • The internal bore of the hose 50 is smooth, i.e. there are no internal anodes. This reduces the pressure losses through the hose 50.

Modifications and improvements may be made to the above without departing from the scope of the present invention. For example, although the attachment means 18 has been illustrated and described above as being located on an inner surface of the hose section 10, it should be appreciated that the attachment means 18 could be located on an external surface of the hose section 10.

Furthermore, although each hose section 10 has been described above as comprising a single attachment means 18, it should be appreciated that each hose section 10 could comprise two or more attachment means located at various positions in/on the hose section 10.

Also, although the sea water suction hose 50 has been illustrated and described above as being installed within a caisson 44 in the hull of an FPSO, it should be appreciated that the sea water hose 50 could be installed in a caisson arranged on the side of an FPSO.

Furthermore, although attachment means 18 has been illustrated and described above as including at least one fixing hole 22 which is used to secure the hypochlorite line thereto, it should be appreciated that the attachment means may comprise any means suitable for attaching the hypochlorite supply line to the hose section 10.