GB2246413A

GB2246413A - Impact protection system

Info

Publication number: GB2246413A
Application number: GB9016173A
Authority: GB
Inventors: Terence Jeffrey Corbishley
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-07-24
Filing date: 1990-07-24
Publication date: 1992-01-29
Anticipated expiration: 2010-07-24
Also published as: GB9016173D0; GB2246413B

Abstract

Mechanical protection of equipment structures and objects, principally those underwater such as pipes 6, from damage by impact loads is achieved by an energy absorbing structure, formed of a jacket 7 of elastomeric or other materials fabricated in tubular, annular, or irregular compartments and filled with liquid. Energy absorption is enhanced by the incorporation of valves in compartment walls to allow the flow of liquid between compartments. Recovery from underwater of the protection structure or the structure or object it is protecting, can be facilitated by the inflation of the compartments (e.g. 8) of the protection structure with air. <IMAGE>

Description

The "Hydrotector" System This invention relates to the mechanical protection of underwater equipment, structures and objects hereinafter referred to as an "installation", from mechanical damage, which may result from impact by fishing gear (trawl boards and beams, dropped objects and anchors.

Protection of installations on the seabee? its presently achieved by installing over them a structure made of steel, concrete or composite glass reinforced plastic. Often the installation of such protection structures poses greater risk of damage to the installation which it is there to protect. The protection structure can, unless piled into the seabed, be dragged to contact and damage the installation. Composite structures, whilst lightweight, are often difficult to install and suffer permanent damage on impact. The invention provides protection by forming an elastic structure enveloping a hydraulic reservoir, ~ which between them absorb the energy of impact. It may also be used to protect general marine, military and land based installations.The entrapment of a volume of liquid within a flexible structure forms an inherent part of the inventions protect#ive capability.

The invention is now described with reference to the accompanying illustrations, listed below.

Figure 1 General illustration of a single tubular protection jacket.

Figure 2 General illustration of multi-bundled tubular protection jacket.

Figure 3 General illustration of submarine installation protection system for a subsea wellhead.

The level of damage that would result to the material of any structure is a function of the energy contained in the body or object making contact on impact with that structure and the area of contact. It is also a function of the ability of the structure to absorb the energy upon impact. The latter facit of mechanical damage is that jor which the Hydrotector system is most relevant.

The principle of the invention is to create an energy absorbing jacket around the pipeline, tubular structure.

object or complete installation to be protected.

The jacket system (1) as illustrated in Figure 1 for a pipeline or tubular member (2), is of annular form and wraps partially or completely around the outside of the pipeline or tubular installation member. The annular void within the jacket is then inflated with liquid, fresh water or seawater, as appropriate, to a suitable pressure. The jacket is fabricated of a suitable elastic material, rubber or polymer, of a thickness to avoid tearing.The outer surface of the jacket may also feature a layer of abrasive resistant and stronger material (3) and can be stiffened with ribs or-slats. Internally, within the enclosed annulus of the jacket there may feature flexible annular or longtitudinal bulkheads (4), which feature two way flow restricting valves (5), to restrict flow of displaced water from the compartments influenced by the impact loads.

Upon impact on the pipeline or tubular structure protected by the jacket, the energy will be absorbed by; a) the displacement of the enclosed volume of water longitudinally and circumferentially around and towards the back of the jacket. b) the elasticity and possibly plastic deformation or stretch of the jacket material and c) the displacement of water through the restrictors, and to a significant contribution by the Added Mass effect of the volume of water displaced by the inflated structure itself.

Where tubular structures are grouped into bundles (6), of equal or unequal size, they may again be enclosed within a circumferential jacket (7), to protect them in the manner described for a single tubular structure, all as illustrated in Figure 2.

Where required the protection may be achieved by multiple layers of annular jackets.

To facilitate recovery of the installation from the seabed, the jacket can be made buoyant by inflating air or other gas, a single or several tubular or other suitable shape membranes (8), housed within the protection jacket.

The protection of an irregular shaped installation, may be achieved with the flexible jacket, but whose shape will depend upon the shape and dimensions of the installation to be protected.

For a typical seabed wellhead or other structure (9), the inflated protection jacket (1) can be placed around it.

When in position the jacket can be inflated with water to the required pressure, so that it assumes the desired shape for protection, which will depend on the form of the jacket, which may be all around and over the structure, as illustrated in figure 3R and B. To accommodate irregular forms, the Hydrotector protection structure can feature tubular members which can be pre-inflated to create the shape required, prior to the main body of the protection system being inflated The construction of the protection jacket can be made up of multiple layers of jackets, to rorm the most suitable shape to achieve the required protection.By suitable design and compartmentalising the protection jacket, compartments and or sections can be deflated for access to the installation with subsequent inflation to reinstate the protection.

Where appropriate the protection jacket can be preformed such that when inflated the shape that it assumes will deflect the impacting object.

The advantage of the invention system are deemed to be; 1) The protective structure is lightweight 2) It can be designed to absorb most, if not all the impact energy.

3) It can be designed to deflect the impacting object.

4) There is no requirement for piling.

5) Irregular seabeds can be accommodated.

6) It can be installed by'drill/work over vessels or small Diving Support Vessels.

7) It may be repaired underwater or recovered and repaired.

8) It is reuseable 9) It can be designed to or deflated to permit access.

Claims

1. A method of protecting a tubular or group of tubular members, other regular or irregular shaped structures or objects particularly thos situated under water, by the installation of a jacket formed of a flexible material, inflated with water to other suitable liquid, which when subjected to any externally applied forceS during n impact from an object or objects, will act as a compliant structure and absorb the impacting energy.

2. A method is claimed in 1. where the internal flexible diaphragm members are intersperesed within the liquid filled jacket to prevent complete deflation in the even of rupture of the jacket.

3. fi method is claimed in 1. and 2. where the diaphragm and jacket can feature flow restrictor valves to retard the flow of the water between compartments displaced during impact.

4. A method is claimed in 1. 2. and 3. where multi-jackets are suitably placed to achieve the required protection.

5. A method is claimed in 1. 2. 3. and 4. by which a tubular or other suitably shaped membrane can be housed within the protection jacket whereby it can be inflated with air or other suitable gas or other medium to derive buoyancy.

6. A method is claimed in 1. 2. 7. and 4. by which irregular shaped installations can be protected by a compartmentalised jacket, which is formed of pre inflated tubular members to produce the general shape of the protective structure, before the main body of the structure is itself inflated.

Amendments to the claims have been filed as follows 1. A method of protecting an underwater object by locating the object within a surrounding elongate jacket formed of a flexible material, the jacket being filled with liquid to form a compliant structure capable of absorbing externally applied impact energy.

2. A method according to claim 1 in which the jacket includes internal flexible diaphragm members that divide the jacket into a plurality of liquid#containing compartments.

3. A method according to claim 2 in which one or more of the diaphragm members is fitted with a flow restrictor valve to allow controlled flow of liquid between adjacent compartments.

4. A method according to any one of the preceding claims in which the liquid is water.

5. A method according to any one of the preceding claims in which a plurality of jackets are provided, one lying within another.

6. A method according to any one of the preceding claims in which the jacket, or at least one of the jackets, includes a membrane inflated with gas to increase the buoyancy of the structure

7. A method according to any one of the preceding claims in which the object is a tubular member or group of tubular members.

8. An underwater structure comprising an object located within a surrounding elongate jacket formed of a flexible material, the jacket being filled with liquid to form a compliant structure capable of absorbing externally applied impact energy.

9. An underwater structure according to claim s in which the jacket includes internal flexible diaphragm members that divide the jacket into a plurality of liquid-containing compartments.

10. An underwater structure according to claim 8 in which one or more of the diaphragm members is fitted with a flow restrictor valve to allow controlled flow of liquid between adjacent compartments

11. An underwater structure according to any one of claims 8 to 10 in which the liquid is water.

12. An underwater structure according to any one of claims 8 to 11 in which a plurality of jackets are provided, one lying within another.

13. An underwater structure according to any one of claims 8 to 12 in which the jacket, or at least one of the jackets, includes a membrane inflated with gas to increase the buoyancy of the structure.

14. An underwater structure according to any one of claims 8 to 13 in which the object is a tubular member or group of tubular members.