Marine Hose

Abstract

To provide a marine hose in which gap can be formed between an inner reinforcing layer group and an outer reinforcing layer group by reliably separating these groups when an inner surface rubber layer and the inner reinforcing layer group are broken, and which comprises a release layer excellent in moldability.SOLUTION: Inner reinforcing layer groups 4, 5, a release layer 6, and an outer reinforcing layer group 7 are laminated in this order from an inner peripheral side between an inner surface rubber layer 3 and a cover layer 9. The release layer 6 has such a specification that the main component of the release layer 6 is PVA and water dissolving temperature is 50°C or more. When the inner surface rubber layer 3 and the inner reinforcing groups 4, 5 are broken, the release layer 6 is released from the inner reinforcing layer groups 4, 5 to form a gap g between them, and fluid L leaked from a flow path 1a inside the inner surface rubber layer 3 flows the gap g and reaches, through a communication pipe 10a, a leakage detector 10 arranged on a hose surface.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a marine hose, and more specifically to a marine hose which is capable of reliably separating the inner reinforcing layer group and the outer reinforcing layer group to form a gap when the inner rubber layer and the inner reinforcing layer group are damaged, and which is provided with a peel-off layer which has excellent formability in the marine hose manufacturing process.

[0002] Marine hoses used to transport fluids such as crude oil by sea, connecting tankers at sea with land facilities, etc., include the so-called double carcass type. Double carcass type marine hoses are made of an inner reinforcing layer group laminated between an inner rubber layer and a cover layer, and an outer Reinforcement layers A structure in which a non-adhesive layer is interposed between the inner rubber layer and the inner reinforcing layer group is known (for example, see Patent Document 1). When the inner rubber layer and the inner reinforcing layer group are damaged, the inner reinforcing layer group and the non-adhesive layer peel off, forming a gap between them. Fluid leaking from the flow path of the marine hose reaches a leak detector installed at the longitudinal end of the hose through this gap, and the fluid leak is detected.

[0003] Conventionally, the non-adhesive layer has been mainly formed of a polyethylene film (paragraph 0020 of Patent Document 1). The polyethylene film has excellent releasability and is therefore suitable for peeling off from the inner reinforcing layer group to form a gap. However, because polyethylene has a large thermal shrinkage, it is difficult to form a non-adhesive layer in which a thin film is wrapped around the inner reinforcing layer group without wrinkles or the like and does not leak. For this reason, a large number of steps are required in the manufacturing process of the marine hose, for example, to make the polyethylene film thinner and carefully wrap it around. Therefore, there is room for improvement in using a film that can reliably separate the inner reinforcing layer group and the outer reinforcing layer group to form a gap, and in improving the moldability of this film. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-265991 A Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a marine hose which can reliably separate the inner reinforcing layer group and the outer reinforcing layer group to form a gap when the inner rubber layer and the inner reinforcing layer group are damaged, and which is equipped with a peel-off layer which has excellent moldability. [Means for solving the problem]

[0006] In order to achieve the above object, the marine hose of the present invention has an inner reinforcing layer group, a release layer, and an outer reinforcing layer group laminated in this order from the inner periphery side between an inner rubber layer and a cover layer, a communication pipe communicating with a gap formed between the inner reinforcing layer group and the release layer and extending to an end of the hose in the longitudinal direction, and a leak detector connected to the communication pipe at the end of the hose in the longitudinal direction and disposed on the surface of the hose, wherein the release layer is formed mainly of PVA and has a water dissolution temperature of 50°C or higher. The inner reinforcing layer group is damaged, and the inner reinforcing layer and the peeling layer are peeled off by the leaking fluid, forming the gap between them. The water dissolution temperature is determined by placing a PVA film test piece of 10 mm x 10 mm x 30 μm in 500 ml of water whose temperatures are changed at 5° C. intervals and measuring the time required for the test piece to completely dissolve. The maximum water temperature when the test piece completely dissolves within 60 seconds is regarded as the water dissolution temperature of the test piece. It is characterized by: Effect of the Invention

[0007] According to the present invention, when the inner rubber layer and the inner reinforcing layer group are damaged, the inner reinforcing layer group and the release layer are peeled off to form a gap between them. The release layer is formed mainly from PVA and has a water dissolution temperature of 50°C or higher, so that it exhibits good peelability with respect to the inner reinforcing layer group, and it is possible to reliably form the gap. Fluid leaking from the flow path inside the inner rubber layer flows through the gap and reaches the leak detector through the communication pipe, which is advantageous for reliably detecting fluid leakage. In addition, because the release layer has small thermal shrinkage due to its material properties, wrinkles are unlikely to occur even if it is a thin layer. Therefore, the PVA film forming this release layer has excellent moldability, which is advantageous for efficiently forming a release layer that does not cause leakage. This contributes to improving the quality and productivity of marine hoses. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram illustrating a marine hose of the present invention. [Diagram 2] 2 is an explanatory diagram illustrating an upper half of the periphery of one end portion in the longitudinal direction of the marine hose in FIG. 1 in an enlarged vertical cross-sectional view. FIG. [Diagram 3] 2 is an explanatory diagram illustrating a cross-sectional structure of a marine hose taken along line AA in FIG. 1. [Figure 4] 2 is an explanatory diagram illustrating an example of an upper half of a longitudinal center portion of the marine hose of FIG. 1 in vertical cross section. FIG. [Diagram 5] 5 is an explanatory view illustrating a state in which the inner rubber layer and the inner reinforcing layer group in FIG. 4 are damaged. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A marine hose according to the present invention will now be described with reference to the embodiments shown in the drawings.

[0010] The embodiment of the marine hose 1 illustrated in Figs. 1 to 4 has connecting ends 2 at both longitudinal ends for connecting another marine hose 1. The connecting ends 2 have a nipple 2b extending in the longitudinal direction of the marine hose 1 and a flange 2a joined to one longitudinal end of the nipple 2b. In general, for example, about eight to ten marine hoses 1 are connected together for use. The dashed-dotted line CL in the figures is a center line that passes through the center of the cross section of the marine hose 1 and extends in the longitudinal direction of the hose. Note that Fig. 3 shows only 1 / 4 of the cross section of the marine hose 1, but the other range (3 / 4) not shown also has the same structure.

[0011] The marine hose 1 is provided with a communication pipe 10a that extends in the longitudinal direction of the hose on the outer circumferential side of the nipple 2b and is inserted from the outside of the hose into the inside of the hose. This communication pipe 10a is connected to a leak detector 10 that is disposed on the surface of the hose at one longitudinal end of the marine hose 1. Various known types of leak detector 10 can be used. In this embodiment, the leak detector 10 is disposed only at one longitudinal end of the marine hose 1, but it may also be disposed at both longitudinal ends, or at least at one longitudinal end.

[0012] Between the nipples 2b at both ends of the marine hose 1, an inner surface rubber layer 3, an inner first reinforcing layer 4, a reinforcing wire layer 5r, an inner second reinforcing layer 5, a peel layer 6, an outer reinforcing layer group 7, a buoyancy layer 8, and a cover layer 9 are laminated coaxially, in this order from the inner circumferential side, around the cylindrical flow path 1a (i.e., around the center line CL). The inner first reinforcing layer 4, the inner second reinforcing layer 5, and the outer reinforcing layer group 7 are fixed to the nipple 2b by nipple wires 4w, 5w, 7w at one end of each, and a fixing ring 2c protruding from the outer circumferential surface of the nipple 2b, etc.

[0013] The inner first reinforcing layer 4, the reinforcing wire layer 5r, and the inner second reinforcing layer 5 constitute the inner reinforcing layer group. Therefore, the peel layer 6 is interposed between the inner reinforcing layer group 4, 5r, 5 and the outer reinforcing layer group 7. The peel layer 6 is bonded to the inner circumferential surface of the outer reinforcing layer group 7 via the intermediate rubber layer 6a laminated on its outer circumferential surface. The inner circumferential surface of the peel layer 6 is laminated on the outer circumferential surface of the inner second reinforcing layer 5, but is not bonded to the inner second reinforcing layer 5. The details of the peel layer 6 will be described later.

[0014] The inner circumferential surface of the inner rubber layer 3 becomes the flow path 1a for the fluid L. Examples of the fluid L include crude oil, gasoline, and LPG. An appropriate material is used for the inner rubber layer 3 depending on the type of fluid L. When the fluid L is crude oil or the like, the inner rubber layer 3 is formed of nitrile rubber or the like having excellent oil resistance.

[0015] The inner first reinforcing layer 4 is configured by laminating a plurality of cord reinforcing layers. The number of the cord reinforcing layers is appropriately set to a required number, for example, about 4 to 30. Each cord reinforcing layer is formed by arranging a large number of rubber-coated reinforcing cords in parallel.

[0016] In each cord reinforcement layer, a large number of reinforcing cords extend at a predetermined angle with respect to the center line CL. In adjacent cord reinforcement layers stacked vertically, the reinforcing cords are arranged so that they are inclined in opposite directions and cross each other. The reinforcing cords are resin fiber cords made of polyester, polyketone, aramid, vinylon, nylon, etc., which are commonly used in marine hoses, or steel cords.

[0017] Each cord reinforcing layer is covered with a thin rubber layer for adhesion, and adjacent cord reinforcing layers are bonded to each other via this thin rubber layer. Also, the inner peripheral surface of the first inner reinforcing layer 4 and the outer peripheral surface of the inner rubber layer 3 are abutted against each other and bonded to each other.

[0018] The reinforcing wire layer 5r is formed by winding a reinforcing wire around the outer circumferential surface of the first inner reinforcing layer 4 in a spiral shape at intervals in the longitudinal direction of the marine hose 1. The reinforcing wire layer 5r is also covered with a rubber layer for adhesion. The outer circumferential surface of the inner first reinforcing layer 4 and the outer circumferential surface of the reinforcing wire layer 5r are abutted and joined. The reinforcing wire layer 5r can be provided as an optional step. The reinforcing wire layer 5r can also be disposed inside the first inner reinforcing layer 4.

[0019] The second inner reinforcing layer 5 and the outer reinforcing layer group 7 each have substantially the same structure as the first inner reinforcing layer 4, and are configured by laminating a plurality of cord reinforcing layers. The inner peripheral surface of the second inner reinforcing layer 5 and the outer peripheral surface of the reinforcing wire layer 5r are abutted and joined. The outer reinforcing layer group 7 is a reinforcing layer that supports the inner reinforcing layer groups 4, 5r, and 5, and resists the impact force (internal pressure) generated in the marine hose 1 when the inner reinforcing layer groups 4, 5r, and 5 are damaged.

[0020] The buoyancy layer 8 is formed of a material that exerts buoyancy to float the marine hose 1 on the sea surface, such as sponge rubber or polyurethane foam. The layer thickness of the buoyancy layer 8 (layer thickness other than at both longitudinal ends) varies depending on the size of the marine hose 1, the required buoyancy, etc., and is, for example, about 60 mm to 300 mm. The outer peripheral surface of the outer reinforcing layer group 7 and the inner peripheral surface of the buoyancy layer 8 are abutted and joined.

[0021] The cover layer 9 is formed of a non-permeable material such as rubber, and has a highly visible line pattern or the like on its surface. An appropriate material having excellent weather resistance, resistance to external damage, etc. is used for the cover layer 9. The outer peripheral surface of the buoyancy layer 8 and the inner peripheral surface of the cover layer 9 are abutted and joined together.

[0022] The release layer 6 is mainly composed of PVA (polyvinyl alcohol) and is water-soluble. In addition to PVA, a small amount of plasticizer is added to adjust the water solubility. Examples of the plasticizers that are added include diethylene glycol, methanol, salicylic acid, lithium chloride, and 2,2-dimethyl-1,3-propanediol.

[0023] The water dissolution temperature of the release layer 6 is 50° C. or higher. PVA with a water dissolution temperature of 50° C. or higher is publicly known and available. μm PVA film test pieces of about 500 mm in size were placed at 5°C intervals. ml The time required for the test piece to completely dissolve is measured. The maximum water temperature at which the test piece completely dissolves within 60 seconds is the water dissolution temperature of the test piece. Therefore, the test piece with the release layer 6 is placed in 500°C, which is less than 50°C. ml When the test piece is placed in water, not all of it will dissolve within 60 seconds.

[0024] In a normal state where there is no fluid leakage from the marine hose 1, the fluid L flows through the flow path 1a as shown in Fig. 4. On the other hand, as shown in Fig. 5, if the inner rubber layer 3 and the inner reinforcing layer group 4, 5r, 5 are damaged, the release layer 6 is pressed by the liquid L leaking from the flow path 1a. This causes the release layer 6 to peel off from the inner second reinforcing layer 5, forming a gap g between them. This gap g is formed to extend in the longitudinal direction of the hose.

[0025] Since the communication pipe 10a communicates with this gap g, the leaked liquid L reaches the leak detector 10 through the communication pipe 10a. As a result, the leak detector 10 detects that the fluid L is leaking from the flow path 1a.

[0026] In this way, when the inner rubber layer 3 and the inner reinforcing layer group 4, 5r, 5 are damaged, the inner reinforcing layer group 4, 5r, 5 and the release layer 6 are peeled off, forming a gap g between them. The release layer 6 is mainly made of PVA and has a water dissolution temperature of 50°C or higher, so it exhibits good peelability from the inner second reinforcing layer 5. This makes it possible to reliably form the gap g extending in the hose longitudinal direction. As a result, this is advantageous for the leak detector 10 to reliably detect fluid leakage from the flow path 1a.

[0027] If the water dissolution temperature is less than 50°C, the water solubility of the release layer 6 is too good, making it difficult to peel the release layer 6 from the inner second reinforcing layer 5. The upper limit of the water dissolution temperature is not particularly limited, but is, for example, about 100°C or about 80°C.

[0028] In the manufacturing process of the marine hose 1, the above-mentioned various components are sequentially laminated on the outer circumferential side of the mandrel to form a molded body. Next, the molded body is placed inside a mold and vulcanized (steam vulcanized) to manufacture the marine hose 1. When forming the release layer 6 in this manufacturing process, the PVA film that forms the release layer 6 is made into a strip and wound helically around the outer circumferential surface of the inner second reinforcing layer 5.

[0029] This release layer 6 (PVA film) has less heat shrinkage than polyethylene, so even a thin layer of 20 μm to 40 μm is unlikely to wrinkle. Therefore, this PVA film has excellent formability. Therefore, it is possible to form the release layer 6 in a spirally wound state by overlapping strip-shaped PVA films with no gaps in the width direction without requiring excessive man-hours. This is advantageous for efficiently forming the release layer 6 that does not leak. As a result, this contributes to improving the quality and productivity of the marine hose 1.

[0030] If the thickness of the release layer 6 is less than 20 μm, it is difficult to achieve a water dissolution temperature of 50° C. or higher. Furthermore, if the thickness is less than 20 μm, the rigidity is insufficient, which is disadvantageous for winding the PVA film while suppressing the occurrence of wrinkles, and good moldability cannot be ensured. If the thickness of the release layer 6 exceeds 40 μm, it is disadvantageous for reducing the weight of the marine hose 1. Therefore, the thickness of the release layer 6 is preferably 20 μm or more and 40 μm or less.

[0031] If the breaking elongation of the release layer 6 is too small or too large, the moldability decreases, so the breaking elongation is preferably 150% or more and 400% or less. This breaking elongation is a value measured in accordance with the test method specified in JIS K7113. The temperature condition is room temperature (about 25°C).

[0032] Furthermore, in order to ensure good moldability and sufficient durability of the release layer 6, the tensile strength is preferably 25 MPa or more and 80 MPa or less. If the tensile strength of the release layer 6 is too low, the durability will be insufficient, and if it is too high, the moldability will deteriorate. This tensile strength is a value measured in accordance with the test method specified in JIS K7113. The temperature condition is room temperature (about 25°C). EXAMPLES

[0033] Five test samples of marine hoses with an inner diameter of 195 mm and the same structure as those shown in Figs. 1 to 4 were manufactured under the same manufacturing conditions (Examples 1 to 3, Comparative Example, and Conventional Example). The differences between the test samples are the peeling layer (layer thickness 30 mm) as shown in Table 1. μmThe specifications are only for the degree of moldability (degree of peelability). The moldability and peelability of each test sample were confirmed as described below, and the results are shown in Table 1. The water dissolution temperatures in Table 1 are values ​​measured by the test method described above. The release layers in Examples 1 to 4 have different physical properties due to differences in the blending of additives, stretching conditions, etc.

[0034] [Moldability] When the test samples were molded, the film forming the release layer was spirally wound around the outer peripheral surface of the inner second reinforcing layer to form the release layer. The manufactured test samples were disassembled to check the occurrence of wrinkles in the release layer and the presence or absence of gaps between the strip-shaped films in the width direction. The cases where there were no wrinkles or gaps that would be problematic in terms of quality were marked with ◯, and the cases where there were ×.

[0035] [Peelability] A piece of about 5cm x 5cm was cut from each test sample, and a test (180° peel test) was conducted in which the peel layer and the inner second reinforcing layer were peeled off by hand. The case where the peel was easily peeled off was marked with ◎, the case where the peel was possible but not easily peeled off was marked with ◯, and the case where the peel was not possible was marked with ×. Therefore, ◎ means that the peelability is the best.

[0036] [Table 1]

[0037] The results in Table 1 show that in Examples 1 to 3, the moldability and releasability of the release layer are both excellent. [Explanation of symbols]

[0038] 1 Marine hose 1a Flow path 2 Connecting end 2a Flange 2b nipple 2c Retaining ring 3 Inner rubber layer 4 Inner first reinforcement layer (inner reinforcement layer group) 4w nipple wire 5 Inner second reinforcement layer (inner reinforcement layer group) 5r Reinforcing wire layer (inner reinforcing layer group) 5w nipple wire 6 Release layer (PVA film) 6a Middle rubber layer 7 Outer reinforcement layer group 7w nipple wire 8 Buoyancy layer 9 Cover Layer 10 Leak detector 10a communication pipe L fluid g Gap

Claims

1. A marine hose having an inner reinforcing layer group, a peelable layer, and an outer reinforcing layer group laminated in this order from an inner circumferential side between an inner rubber layer and a cover layer, the marine hose further comprising a communication pipe communicating with a gap formed between the inner reinforcing layer group and the peelable layer and extending to an end portion in a longitudinal direction of the hose, and a leak detector connected to the communication pipe at the end portion in the longitudinal direction of the hose and disposed on a surface of the hose, the release layer is formed mainly from PVA and has a water dissolution temperature of 50° C. or higher, and the inner reinforcing layer group and the release layer are peeled off by fluid leaking out when the inner reinforcing layer group is damaged, forming the gap between them, The water dissolution temperature is determined by immersing a PVA film test piece having a size of 10 mm × 10 mm × 30 μm in 500 ml of water whose temperatures are varied at 5° C. intervals and measuring the time required for the test piece to completely dissolve, and the highest water temperature when the test piece completely dissolves within 60 seconds is regarded as the water dissolution temperature of the test piece.

2. 2. The marine hose according to claim 1, wherein the release layer has a layer thickness of 20 μm or more and 40 μm or less.

3. 3. The marine hose according to claim 1, wherein the break elongation of the release layer is 150% or more and 400% or less.

4. 4. The marine hose according to claim 1, wherein the release layer has a tensile strength of 25 MPa or more and 80 MPa or less.

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