US 3736759 A
The invention applies to sheaths for protecting underwater bodies such as piles by surrounding the body with the lower end of the sheath secured to the body and the space between the sheath and the body filled with a yieldable filler material. The improvement is that the filler material is an expandible, synthetic material expanded in place between the shell and the body to form a closed-cell foam having a snug, sealing bond with the surface of the body.
Claims available in
Description (OCR text may contain errors)
Unlted States Patent 11 1 1111 3,736,759 Bliise 1 51 June 5, 1973 541 PILE COVERING 3,181,300 5/1965 Plummer ..61/54 3,661,506 5/1972 Watkins 1 ..61 54  Inventor g 2000 Hamburg 3,403,520 10/1968 Goodman ..61/50 ermany  Assignee: Schlegel Manufacturing Company, FOREIGN PATENTS OR APPLICATIONS Rochester, 279,313 10/1927 Great Britain ..61/54 22 Filed: Feb. 10,1972
Appl. No.: 225,217
 Foreign Application Priority Data Feb. 17, 1971 Germany ..P 21 07 446.4
 US. Cl ..61/54  Int. Cl. ..E02d 5/60  Field of Search 61/54, 50
 References Cited UNITED STATES PATENTS 1,013,758 1/1912 Fox and Hatcher ..61/54 2,846,852 8/1958 Cappel ....6l/50 2,874,548 2/1959 Drushel ct al. ..61/54 Primary ExaminerDavid .l. Williamowsky Assistant ExaminerAlexander Grosz Attorney-Cumpston, Shaw & Stephens  ABSTRACT The invention applies to sheaths for protecting underwater bodies such as piles by surrounding the body with the lower end of the sheath secured to the body and the space between the sheath and the body filled with a yieldable filler material. The improvement is that the filler material is an expandible, synthetic material expanded in place between the shell and the body to form a closed-cell foam having a snug, sealing bond with the surface of the body.
7 Claims, 6 Drawing Figures PILE COVERING TI-IE INVENTIVE IMPROVEMENT Corrosion-resistant coatings for underwater bodies exposed to water, and especially to sea water, are of limited value, and the cost of applying and renewing such coatings is so high compared to their effectiveness that it is often best to tolerate gradual degradation than to try protective coatings. A protective sheath offers more corrosion resistance, and US. Pat. No. 2,874,548 has suggested such a sheath formed of a pilesurrounding shell of synthetic material filled with grease or asphalt. Grease, however, has the disadvantage of gradually leaking into the surrounding water to cause pollution unless the shell is sealed very carefully. Also, suitable greases are quite expensive. Asphalt has the disadvantage that a mixture adjusted for high solidity and hardness does not seal to the underwater surface to be protected so that moisture is likely to creep in between the asphalt and the pile to cause corrosion. A viscous asphalt consistency may seal better to the underwater body, but may pollute the surrounding water, like grease, unless the shell is carefully sealed. Also, grease and asphalt are quite heavy and require handling of large masses of material to produce such sheaths.
The invention aims at a protective sheath for piles and other underwater bodies to satisfactorily protect against corrosion without risking pollution of the water and without requiring large masses of filler material to be handled during installation. The invention seeks a better and more efficient, corrosion-resistant sheath installed relatively easily and economically.
SUMMARY OF THE INVENTION The invention applies a water-impervious shell around an underwater body secured to the body at the lower region of the shell and the body filled with a yieldable filler material, and improves on such an arrangement by using a filler material that is an expandible synthetic material expanded in place between the shell and the body to form a closed-cell foam having a snug, sealing bond with the surface of the body.
DRAWINGS FIGS. 1 and 2 are partially schematic, partially fragmentary, vertical longitudinal cross-section of preferred embodiments of the inventive pile covering;
FIG. 3 is a partially schematic, horizontal crosssection of a preferred embodiment of the inventive pile covering;
FIG. 4 is a partially schematic, horizontal crosssection of the inventive pile covering applied to a sheet piling; and
FIGS. 5 and 6 are partially schematic, horizontal cross-sections of alternative preferred embodiments of the inventive pile covering.
DETAILED DESCRIPTION As shown in FIG. 1, pile l is surrounded by a shell or tube 3 of synthetic material extending down to a desired depth of, for example, 2 meters below low tide, and extending above water surface 2 to above the reach of the water. Tube 3 is preferably formed of a tough, elastic, thermoplastic material such as, for example, polyvinyl chloride of a Shore D hardness of 82. The space between tube 3 and pile 1 is filled with expanded, synthetic resin 4, such as phenol resin foam or polyurethane foam. In the bottom region of the sheath, a higher density foam 5 is used to secure a high quality,
dense sealing bond with the surfaces of pile l and shell 3 to provide better protection against the penetration of water. Underlying collar or bottom plate 6 can be made permanent and sealed to pile l and shell 3, or plate 6 can be used as a mounting aid and can be removed after sheath installation, because high density foam 5 assured sufficient water impermeability.
To mount the sheath of FIG. 1, pile 1 is first cleaned in the zone to be protected or at least in the zone to be covered by the lower end of shell 3. Then bottom plate 6, which can be sectioned or segmented, is fitted around pile 1 and sealed to pile by sealing 7. Then, tube 3 is seated on collar 6 and sealingly connected to collar 6 by sealing 8. The annular space between pile 1 and shell 3 is then pumped empty and dried, using conventional drying agents and means. When the surface of pile 1 and the inner surface of shell 3 are sufficiently dried, the denser foam 5 is formed in the bottom region of shell 3, and the lighter foam 4 of lower specific gravity is formed above high density foam 5. Foams 4 and 5 both form a snug sealing bond with pile 1 and serve to provide both the mechanical bond between pile 1 and shell 3, and the water sealing around pile 1. Preferably, shell 3 and foam 4 are each yieldable to follow any flexure movement of pile 1.
The light weight of expanded, synthetic filler material 4 has many advantages in simplifying production and installation and presenting fewer problems regarding statics. However, it has also been found that when foam 4 solidifies on pile 1, it becomes sealingly bonded to the surface of p'ile l, and the multitude of closed cells form walls sealingly bonded to the surface to be protected to form a system of consecutive barriers to moisture. It the outer wall of a cell breaks to let in water, further penetration by the water is stopped by subsequent cell walls for an extremely efficient moisture barrier. In addition, foams 4 and 5 preferably contain materials capable of absorbing any water that enters by penetration or diffusion, thus forming a drying agent rendering such water harmless. Foams 4 and 5 can also contain corrosion inhibitors further protecting pile 1.
High-density foam 5 aids in preventing penetration of water from below and forms an additional water or vapor barrier at the lower end of shell 3. Foam 5 preferably forms a'secure sealing bond with pile l and with shell 3, and also forms a secure bond with foam 4 on top of foam 5.
The high-density foam 5 forming a moisture barrier at the bottom of shell 3 of FIG. 1, can be supplemented or replaced by a different layer capable of forming a sealing bond with pile 1 and shell 3, and formed, for example, of a permanently plastic or permanently elastic material. Also, a highly viscous liquid can be used for a vapor barrier. No special mechanical retaining means is required for a permanently elastic or a comparably stiff, but permanently plastic vapor barrier (although this may be desired in some instances), but a viscous liquid vapor seal is most suitable where the lower end of the sheath is mechanically connected to the underwater surface without any coarse openings allowing leakage. When the viscosity of the liquid is so high compared to the size of any openings so that the liquid is safely contained in the sheath and cannot escape, the liquid sealant can be at a higher pressure than the outside water pressure. Then any openings or pores in the sheath are blocked from the inside by the highly viscous liquid so that the water cannot enter. Since the expanded foam filler above the. liquid has a low specific gravity, the pressure on the liquid sealant will normally be less than, or at least no higher than the outside water pressure. Then, it must be assumed that the water will penetrate through openings or pores in the sheath and cannot be excluded from the lower joint between the shell and the underwater body. The viscous liquid may nevertheless provide an adequate moisture barrier if the liquid has a lower specific gravity than water. Then the water that penetrates will urge the sealing liquid upward against the foam which forms a mechanical barrier preventing the sealing liquid from rising any higher. The viscous liquid is then capable of forming an effective barrier between any water penetrating the sleeve, and the foam disposed above the liquid.
If such a highly reliable moisture barrier is formed at the bottom of the shell between the foam and any penetrating water, then the sealing requirements for the foam bond to the surface of the underwater body can be reduced and relatively low-density foams are frequently adequate.
Suitable filler materials for the inventive sheath are expanded synthetic materials that are resistent to moisture, are capable of being applied to the underwater surface in a liquid or pasty expanded condition, form a closed-cell foam, andform a secure, sealing bond with the underwater surface. Somewhat yieldable foams are preferred that are plastic or elastic enough to prevent the foam from peeling off the underwater surface from any deformation or flexure of the sheathed body. Examples of suitable expandible materials are preferably formed of unsaturated polyester resins such as expanded polyurethane materials composed of polyoles and polyisocyanates in a 1:1 ratio preferred for their stability and elasticity.
The preferred foams may use fillers such as expanded clay or expanded glass spheres. The preferred density of the expanded filler material preferably ranges from 100 to 300 kilograms per cubic meter, and the expanded filler material, and the material of shell 3 are preferably selected so that the foam forms a secure, sealing bond with both pile 1 and shell 3. Preferably shell3 is formed of a tough, elastic material such as a thermoplastic synthetic material. A preferred example is polyvinyl chloride and copolymers with suitably adjusted hardness.
Shell 3 for protecting pilings is preferably in the form of a tube as illustrated, and it does not matter whether tube 2 is peripherally closed and telescoped over pile l, or whether a slit or sectioned tube is wrapped around pile l and then closed. Shell 3 preferably has internal protrusions or recesses ensuring positive tension and shear resistant engagement with foam materials d and 5 whenever the sealing bond between foams 4 and 5 and shell 3 does not assure an adequate bond without such protrusions. Shell 3 must withstand the pressure developed in expanding foam 4 inside shell 3, and also withstand any unsymmetrical external load, preferably without affecting the bond between shell 3 and filler foam 4..A firm bond of shell 3 with foam 4 is particularly important where large underwater surfaces have to be protected by force transmission via the foam. For extruded tubes or shells 3, suitable protrusions or recesses are preferably in the form of grooves.
Instead of using pre-formed tubes for shell 3, a shell can be made from materials shaped at the site. For example, a filler material can be applied to pile ii and then a liquid or pasty material can be laid over the filler to solidify and form shell 3. Preferred materials for such a shell are synthetic materials having a very smooth surface resisting marine growth and reducing the risk of ice formation. A marine growth inhibitor can be included in the shell material for further protection.
The preferred method of applying the sheath of FIG.
l is to clean pile l to remove dirt and oil, attach collar 6 at the desired depth, and seal collar 6 to pile l by sealing 7. Then tube 3 is telescoped over pile l and sealed to collar 6 by sealing 8, and the annular space between shell 3 and pile l is pumped empty, dried out, and the desired filler material is expanded into the dry space. Preferably a vapor barrier is arranged at the bottom of shell 3 such as the preferred high-density foam 5 as illustrated in FIG. I.
In most circumstances, it is sufficient to protect pile i only to the depth of a few meters below the low tide surface of the water rather than for the entire depth of pile 1. Corrosive attack is usually limited to the area from just below low tide to just above high tide water levels so this is all that needs protection.
Referring to FIG. 2, the area of pile I to be protected is surrounded by hose 13 of flexible, tough material such as a fabric-reinforced synthetic sheet or foil. Hose 13 is suspended at its upper end in any suitable manner, and its lower end M is tightly bound to pile 11 without any coarse openings. In the space between pile land hose 13, there is a bottom layer of a highly viscous liq uid 15 forming a liquid seal, a superposed layer 16 of expanded, closed-cell elastic material. Layer I16 preferably rests snugly against pile l and hose 13, but need not be completely sealed to either. On top of layer 116, is a padding or filler material 17 of expanded foam that fills hose 1 .3 and spaces it from pile l and is preferably yieldable in response to exterior mechanical strain.
Sealing liquid 15 preferably has a lower specific gravity than water, and it is preferably viscous enough and tough enough so that it will either be pressed out through any gaps around lower end 114 under the pressure of superposed layers of filler material, or pressed upwardly through or past layer 16 under the pressure of water that may enter from below. Liquid 15 must be hydrophobic (water-repellent) and have a good adhesiveness to pile l and hose 13 such as some types of oil that would form a safe barrier to water.
The left side of FIG. 2 shows sealing liquid 35 under a pressure exceeding that of the surrounding water with liquid 15 preventing water from penetrating through any gaps around sealing zone M. The right side of FIG. 2 shows sealing liquid 15 under pressure less than the surrounding water so that some water 18 has entered through zone M. However, water 18 is retained by seal- .ing liquid 15, which in turn is retained by foam layer 16.
When the filler material adheres to hose i3 sufficiently, or when a tension-resisting bond between shell 13 and filler 117 is not required, the inside of shell 33 can be smooth. When a firm mechanical connection is required between shell 3 or 13 and filler foam material, the inner surface of the shell can have protrusions such as the dovetailed ribs 30 illustrated in FIG. 3. Such an innerloclring interior surface for the shell is preferred when large surface areas are involved, or when the surface to be protected is planar as in FIG. 4 which shows sheet piling 20 protected by a shell 21 of synthetic material having dovetailed shaped corrugations 22 forming a positive connection between shell 21 and the expanded synthetic material 23 which fills the space between shell 21 and sheath piling 20.
The protrusions on the shell may be large enough to serve as spacers from the surface to be protected as indicated in FIGS. 5 and 6. The shell of FIG. 5 has radial ribs 24 which are spaced away from the surrounded piling by a small clearance. Spaces between ribs 24 are sealed by an expanded synthetic resin. Ribs 26 of the embodiment of FIG. 6 are fundamentally similar except for approaching the surrounded pile in a somewhat tangential rather than radial direction in the interests of better yieldability.
Persons wishing to practice the invention should remember that other embodiments and variations can be adapted to particular circumstances. Even though one point of view is necessarily chosen in describing and defining the invention, this should not inhibit broader or related embodiments going beyond the semantic orientation of this application but falling within the spirit of the invention. For example, those skilled in the art will appreciate the many materials and constructions usable in various circumstances to protect underwater bodies.
l. A pile sheathing method comprising:
a. securing a collar to said pile at the depth of said sheathing;
b. arranging a tube around said pile in spaced concentrical relation with said pile;
c. sealing the lower end of said tube to said collar;
d. pumping the water out of the space between said tube and said pile;
e. drying said pile and the space between said pile and said tube;
f. placing an expandible, synthetic material in said space; and
g. expanding said material to form a closed-cell foam bonded to said pile.
2. The method of claim 1 including expanding a highdensity, synthetic foam material in the bottom of said tube, and expanding a lower density foam in said tube above said high-density foam.
3. The method of claim 1 including expanding a highdensity, synthetic foam material to form a closed-cell foam sealing the lower end of said tube to said pile.
4. The method of claim 1 including using a permanently elastic material to form a sealing bond between the lower end of said tube and said pile.
S. The method of claim 1 including usinga permanently plastic material to form a sealing bond between the lower end of said tube and said pile.
6. The method of claim 1 including using a waterrepellent viscous liquid material to form a seal between the lower end of said tube and said pile.
7. The method of claim 1 including binding the lower end of said tube to said pile to form said collar.
i l i i