EP0295254B1 - Amelioration apportee a la protection des pilots - Google Patents

Amelioration apportee a la protection des pilots Download PDF

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Publication number
EP0295254B1
EP0295254B1 EP87901546A EP87901546A EP0295254B1 EP 0295254 B1 EP0295254 B1 EP 0295254B1 EP 87901546 A EP87901546 A EP 87901546A EP 87901546 A EP87901546 A EP 87901546A EP 0295254 B1 EP0295254 B1 EP 0295254B1
Authority
EP
European Patent Office
Prior art keywords
wrapping
pile
sheet
around
sealant
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP87901546A
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German (de)
English (en)
Other versions
EP0295254A1 (fr
Inventor
Anthony Edward John Strange
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NICC Ltd
Original Assignee
NICC Ltd
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Filing date
Publication date
Application filed by NICC Ltd filed Critical NICC Ltd
Publication of EP0295254A1 publication Critical patent/EP0295254A1/fr
Application granted granted Critical
Publication of EP0295254B1 publication Critical patent/EP0295254B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
    • E02D5/22—Piles
    • E02D5/60—Piles with protecting cases

Definitions

  • This invention relates to the protection of piles or risers, such as those of oil rigs, piers or jetties. For convenience, the specification will simply refer to piles.
  • Liddell Another drawback with Liddell is that by rotating from one end, long slim pole pieces are bound to twist, and there will be uneven tension in the wrapping. It will tend to be tighter at the top than at the bottom.
  • a pile wrapping comprising a flexible sheet with substantially rigid members along substantially the entire length of the opposed edges which are adjacent when the wrapping is positioned around a pile, the members affording means by which the wrapping can be tightened around the pile, characterised in that said members are in the form of outwardly extending flanges to provide counter-abutments for the application of a tool by which the members can be closed together to impose hoop stresses on the wrapping, and in that said flanges have apertures at intervals along their length to accept fastening elements securable while the hoops stresses are maintained.
  • the sheet will have a certain elasticity, but the hoop stresses applied can be made sufficient to prevent the sheet being sucked clean off the pile by wave action. They can also be evenly spread over the length of the wrapping.
  • the sheet preferably comprises an outer skin of water impermeable flexible material, such as reinforced plastics sheet, and an inner layer of liquid permeable material such as felted or porous plastics material bonded to the skin and impregnated with a water resistant sealant.
  • the outer skin may have a thickness of the order of 3 mm, and a suitable material is that used for the skirts of hovercraft.
  • the thickness of the inner layer may be of the order of 6 mm, or at least sufficient to accommodate to variations in surface profile of that order of magnitude.
  • the wrapping is intended to go once around the pile, which is normally cylindrical.
  • the inner layer may have an extension beyond one of the opposed edges to tuck under the opposite one.
  • the sealant impregnated in the inner layer may have other properties beyond just being water resistant. It may incorporate corrosion inhibiting and anti-fouling components. Preferably, it will be in the form of a thixotropic gel and not form a permanent bond to a pile surface. Also the fastening means will generally be releasable, so that the wrapping can be easily removed for inspection, and later re-used.
  • the inner layer and sealant will generally be covered by a removable backing sheet on manufacture, which will be discarded before positioning around the pile.
  • the wrapping sheet may also be adapted to form an element of a cathodic protection system, being a carrier for sacrificial anode material, or providing a jacket with a high dielectric constant, for example. It could also carry anti-fouling material externally.
  • the sheet may be outwardly provided with handles so that divers can manoeuvre it into position. Also, it will be advantageous to have temporary strap fasteners for holding the wrapping around a pile during an initial phase while at least some of the fastening elements are secured. Conveniently, there will also be gauge marks on the outside of the sheet to provide an indication of the hoop stresses imposed.
  • the fastening elements will usually be bolts.
  • a method of protecting a pile comprising wrapping a sheet as outlined above around the pile, drawing said opposed edges together by at least one said tool to create hoop tensions that are resistant to wave suction forces, securing said fastening elements while the hoop stresses are maintained, and removing said tool or tools.
  • tools may be engaged through some of the apertures to draw the opposite edges together.
  • Bolts are then engaged through others of said apertures in a first securing operation, the tools are removed, and replaced by bolts in a second securing operation.
  • the wrapping will usually be positioned at least partially under water and during the initial stages it will conveniently be supported by buoyancy bags as it is positioned by divers around the pile.
  • the sheet is of composite construction having an outer skin 1 of material such as nylon reinforced Neoprene, 3mm thick, similar to hovercraft skirt material. Bonded to the rear side of this is an inner layer 2 of polypropylene felt, 6mm thick and impregnated with a polymeric thixotropic water-displacing gel sealant, formulated to act as a host for corrosion inhibitors and/or anti-foulants. It will be effective over a wide temperature range, say -40°C to 150°C. On manufacture this felt is protected by a peel-off backing sheet 3, which remains during transport and handling and is only removed by the divers as they fit the wrapping around the pile. Handles 4 to assist that fitting operation are bonded or otherwise attached to the outer face of the skin 1, as are straps 5 and fasteners 6 for temporary use as described below. The skin 1 also has permanent datum marks 7 for checking the stability of the wrapping.
  • the skin 1 also has permanent datum marks 7 for checking the stability of the wrapping.
  • Sealing members 8 in the form of substantially rigid flanges extend along the edges of the sheet that are to meet when it has been wrapped around a pile. They will project radially outwardly and each has a series of apertures 9 which register when the wrapping is in place.
  • the inner layer 2 is extended beyond one of the flanges 8 to form a flap 10 which will tuck under the opposite inner edge portion of the layer 2 and form an overlap, thus ensuring a good seal.
  • the flanges 8 may extend the full length of their respective edges, but if several are to be used in series along a pile, the flanges 8 will be short of each end, by 75mm or thereabouts, for reasons explained below.
  • Figures 1 and 2 show a hybrid, with the flanges 8 short at the top end only.
  • the sheet is folded concertina fashion as shown in Figure 1. It may be loosely held thus by ropes or straps. It is then supported by varianble buoyancy bags and floated to the pile to be wrapped. Divers release and unfold it, wrapping it around the pile, which will have been locally cleaned as mentioned above. Once roughly in place, it can be loosely secured by the straps 5 and fasteners 6 as shown in Figure 2, and usually one at the top, one at the bottom and one at the middle will suffice. The wrapping can then be adjusted longitudinally of the pile 11.
  • hydraulic rams 12 as shown in Figure 5 are used, attached to a diver operated handpump 13 via flexible hoses 14. These have swivel connections 15 at their ends to the rams 12 and to the T-pieces 16 or manifolds at the pump 13. Although only two rams are shown, for wrappings of any length it will be preferred to use three, applied to the top, bottom and middle of the members 8 adjacent the straps 5.
  • the ram rods 17 are inserted through the registering bolt apertures 9 and quick-lock nuts are fitted to their ends. The rams are then briefly actuated to apply a light tension to the wrapping.
  • the datum marks 7 are used to measure and note the extension achieved, and this will be compared against a table, and recorded for future reference and checks.
  • Such a wrapping can be removed by reversing this procedure. Unless its removal is occasioned by damage it will normally be possible to replace it.
  • polyester reinforced polychloroprene is one further example being considered.
  • a further application is to use the system as a carrier for anti-foulant materials, preventing marine growth build up and consequent increase in current drag forces on subsea platform legs, risers and caissons.
  • This could be achieved by providing an additional outer skin, conveniently a foamed polymer matrix for the anti-foulant material, such as copper particles. If used solely for this purpose the inner sealant layer could be dispensed with. It will be understood however, that a single wrapping could combine any of these functions.

Landscapes

  • Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Mining & Mineral Resources (AREA)
  • Paleontology (AREA)
  • Civil Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Bulkheads Adapted To Foundation Construction (AREA)
  • Piles And Underground Anchors (AREA)

Abstract

Une enveloppe de protection pour pilots a la forme d'une feuille flexible (1, 2) qui, lorsqu'elle entoure un pilot (11), comprend deux bords contigus. Ceux-ci présentent des abouts (8) qui, lors de l'utilisation, sont pressés l'un contre l'autre par un outil mécanique et fixés de façon appropriée par des écrous (19) et des boulons (18). La tension tangentielle induite dans l'enveloppe permet aux pilots de résister aux forces d'aspiration des vagues. L'enveloppe peut comporter une couche intérieure (2) contenant un agent d'étanchéité résistant à l'eau placé en contact étroit avec le pilot lors de l'application de la tension. L'enveloppe peut également présenter des propriétés anti-salissures et des propriétés de protection cathodique.

Claims (12)

1. Enveloppe pour pieu comprenant une feuille souple (1, 2) munie d'éléments sensiblement rigides (8) sur sensiblement toute la longueur des bords opposés qui sont adjacents lorsque l'enveloppe est placée autour d'un pieu (11), les éléments (8) formant des moyens par lesquels l'enveloppe peut être serrée autour du pieu (11), caractérisée en ce que lesdits éléments (8) sont sous forme de rebords qui s'étendent vers l'extérieur pour former des contrebutées pour l'application d'un outil (12) par lequel les éléments peuvent être fermés ensemble pour imposer des contraintes périphériques sur l'enveloppe, et en ce que lesdits rebords (8) comportent des ouvertures (9) à des intervalles suivant leur longueur pour recevoir des éléments de fixation (18) qui peuvent être fixés tandis que les contraintes périphériques sont maintenues.
2. Enveloppe selon la revendication 1, caractérisée en ce que la feuille comprend une peau externe (1) de matériau souple imperméable à l'eau, telle qu'une feuille de matière plastique renforcée, et une couche interne (2) de matériau perméable aux liquides tel qu'une matière plastique feutrée ou poreuse, liée à la peau (1) et imprégnée d'un matériau d'étanchéité résistant à l'eau.
3. Enveloppe selon la revendication 2, caractérisée en ce que la couche interne (2) comporte un prolongement (10) au-delà de l'un desdits bords opposés pour pénétrer sous l'autre partie formant bord opposé lorsque l'enveloppe est placée autour d'un pieu (11).
4. Enveloppe selon la revendication 2 ou 3, caractérisée en ce que le matériau d'étanchéité imprégné a des propriétés inhibant la corrosion et/ou anti-salissure, et est un gel thixotrope.
5. Enveloppe selon la revendication 2, 3 ou 4, caractérisée en ce que le matériau d'étanchéité imprégné ne forme pas une liaison permanente avec la surface d'un pieu, et dans laquelle les éléments de fixation (18) sont amovibles.
6. Enveloppe selon l'une quelconque des revendications 2 à 5, caractérisée en ce que la couche interne (2) et le matériau d'étanchéité sont recouverts par une feuille dorsale (3) amovible rejetée avant le positionnement autour d'un pieu.
7. Enveloppe selon l'une quelconque des revendications précédentes, caractérisée en ce que la feuille (1, 2) est adaptée pour former un élément d'un système de protection cathodique, en constituant un support pour un matériau d'anode réactive ou en formant une chemise à constante diélectrique élevée.
8. Enveloppe selon l'une quelconque des revendications précédentes, caractérisée en ce que la feuille (1, 2) est munie à l'extérieur de poignées (4) pour favoriser le positionnement de l'enveloppe, et de moyens de fixation à bandes temporaires (5, 6) pour maintenir de manière lâche l'enveloppe en position autour d'un pieu tandis qu'au moins certains des éléments de fixation (8) sont fixés.
9. Enveloppe selon l'une quelconque des revendications précédentes, caractérisée en ce que la feuille (1, 2) est munie à l'extérieur de marques d'étalonnage (7) pour donner une indication des contraintes périphériques imposées.
10. Enveloppe selon l'une quelconque des revendications précédentes, caractérisée en ce que les éléments de fixation sont des boulons (18).
11. Procédé de protection d'un pieu, comprenant le positionnement d'une feuille (1, 2) selon l'une quelconque des revendications précédentes autour du pieu (11), le rapprochement par traction desdits bords opposés par ledit ou lesdits outils (12) pour créer des tensions périphériques qui sont résistantes aux forces d'aspiration des vagues, la fixation desdits éléments de fixation (18) tandis que les contraintes périphériques sont maintenues, et le retrait dudit outil ou desdits outils.
12. Procédé selon la revendication 11, caractérisé en ce que lesdits outils (12) sont engagés dans certaines desdites ouvertures (9) pour tirer ensemble les bords opposés, après quoi des boulons (18) sont introduits dans d'autres ouvertures parmi lesdites ouvertures (9) dans une première opération de fixation, et dans lequel les outils (12) sont retirés et remplacés par des boulons (18) dans une seconde opération de fixation.
EP87901546A 1986-02-20 1987-02-20 Amelioration apportee a la protection des pilots Expired - Lifetime EP0295254B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB868604285A GB8604285D0 (en) 1986-02-20 1986-02-20 Protection of piles
GB8604285 1986-02-20

Publications (2)

Publication Number Publication Date
EP0295254A1 EP0295254A1 (fr) 1988-12-21
EP0295254B1 true EP0295254B1 (fr) 1991-11-06

Family

ID=10593424

Family Applications (1)

Application Number Title Priority Date Filing Date
EP87901546A Expired - Lifetime EP0295254B1 (fr) 1986-02-20 1987-02-20 Amelioration apportee a la protection des pilots

Country Status (7)

Country Link
EP (1) EP0295254B1 (fr)
JP (1) JPH01501641A (fr)
AU (1) AU599958B2 (fr)
BR (1) BR8707601A (fr)
GB (1) GB8604285D0 (fr)
OA (1) OA08904A (fr)
WO (1) WO1987005066A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5102265A (en) * 1990-08-31 1992-04-07 T C Manufacturing Co., Inc. Adjustable width split sleeve and method of forming ends thereto
US5476576A (en) * 1991-08-15 1995-12-19 Winn And Coales International Limited Impressed current cathodic protection system
GB9207624D0 (en) * 1992-04-08 1992-05-27 Strange Anthony E J Improvements relating to the protection of corrosion-susceptible members

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE411382A (fr) *
AU422555B2 (en) * 1966-09-09 1972-03-22 Divework Limited Improved method of and means for protecting underwater woodwork against attack by marine organisms
US3939665A (en) * 1974-01-08 1976-02-24 Bethlehem Steel Corporation Method for protecting metal H-piling in underwater environments and protected H-piling
FR2337792A1 (fr) * 1976-01-07 1977-08-05 Liddell Orval Enveloppe ou appareil assurant la protection d'un element metallique de structure, contre la corrosion
AU495705B2 (en) * 1976-06-28 1978-01-05 E. Liddell Orval Apparatus for protecting metallic structural elements against corrosion

Also Published As

Publication number Publication date
EP0295254A1 (fr) 1988-12-21
GB8604285D0 (en) 1986-03-26
OA08904A (en) 1989-10-31
WO1987005066A1 (fr) 1987-08-27
AU599958B2 (en) 1990-08-02
JPH01501641A (ja) 1989-06-08
BR8707601A (pt) 1989-03-14
AU6949887A (en) 1987-09-09

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