JPS61248989A - Damage detection type high-pressure flexible pipe - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field 1 The present invention relates to a high-pressure flexible tube used when transporting fluid at high pressure.

rPrior Art J High-pressure flexible pipes are used when crude oil, etc. is transported under high pressure between land and sea or in the sea.

There are two types of high-pressure flexible tubes: dynamic and static types, but both types basically have an internal plastic tube with a metal reinforcement layer and a plastic jacket layer around its outer circumference. .

Of course, the Guinamic type has stricter usage conditions.

FIG. 3 shows an example of the cross-sectional structure of a dynamic type high-pressure flexible pipe suspended from the sea to the sea, and this will be briefly explained below.

In Fig. 3, 1 is an interlock tube, 2 is an internal plastic tube made of nylon or the like formed on the outer periphery of the interlock tube l by extrusion means, and 3 is a radial metal tube formed by a C-shaped strip or a Z-shaped strip. The reinforcing layer 4 is an axial metal reinforcing layer formed by winding a large number of flat strips at a long pitch around the outer periphery of the metal reinforcing layer M3, and 5 is an external plastic jacket formed on the outer periphery of the metal reinforcing layer 4 by extrusion means. be.

In the above, the interlock tube 1 and the internal plastic tube 2 constitute a pipe body, and the interlock tube 1 has a weight of 1, for example, 250 to 350 kg/c inside the pipe.
When sending oil under high pressure rn', it suppresses the elongation of the pipe in the axial direction.

The radial metal reinforcing layer 3 suppresses the pipe from expanding in the radial direction during the high-pressure oil feeding.

The axial metal reinforcing layer 4 withstands the weight of the pipe when it is suspended and the axial load when tidal waves and the like act on it.

The outer plastic jacket 5 prevents seawater from entering the metal reinforcing layer.

As described above, high-pressure flexible tubes have been studied from various angles in terms of material, strength, fatigue characteristics, etc., and can be said to be extremely robust structures.

``Problems to be solved by the inventionj'' By the way, in the case of the above-mentioned high-pressure flexible tube, it relies on various metal reinforcing layers to maintain high strength, but for example, if the outer plastic jacket is torn due to an unexpected accident, If seawater invades, the metal reinforcing layer will corrode and its life will be shortened in a short period of time.

Of course, such a situation must be detected early and emergency measures taken, but conventional high-pressure flexible pipes do not have a means to detect seawater intrusion due to the above-mentioned breakage accident, which delays the discovery of the accident and prevents oil leakage. It may cause marine pollution.

In view of the above-mentioned problems, the present invention aims to provide a high-pressure flexible pipe that has a special layer that can detect seawater intrusion into the pipe, thereby enabling early detection of damage to the external plastic jacket. .

Means for Solving Problems] The present invention provides a high-pressure flexible tube in which a metal reinforcing layer is provided between an inner plastic tube and an outer plastic jacket. The feature is that an oil-immersed insulating layer is interposed between the capacitance and the capacitor to detect changes in capacitance.

r Effect 1 In the case of the high-pressure flexible tube according to the present invention 1 For example, are two metal reinforcing layers sandwiching an oil-immersed insulating layer used as both electrodes?

Alternatively, a voltage is applied between one metal reinforcing layer and external seawater as both electrodes, and a capacitance measuring device is used to monitor whether or not there is a change in capacitance during this time.

In the above, when there is no damage to the external plastic jacket of the high-pressure flexible tube and no seawater intrudes into the tube, that is, under normal conditions without any accidents, the capacitance does not change.

However, when seawater intrudes into the pipe due to the jacket damage, and the infiltrated seawater (conductive) penetrates into the oil-immersed insulating layer, the insulation resistance value of the oil-immersed insulating layer decreases and the capacitance changes significantly. .

Therefore, it is clear that the high-pressure flexible tube was damaged due to such a change in capacitance.

rEmbodiment j Hereinafter, embodiments of the high-pressure flexible tube of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of a Guinami Tsuik type high-pressure flexible tube.

In the figure, 11 is an interlock tube, 12 is an internal plastic tube made of nylon or the like formed on the outer periphery of the interlock tube 11 by extrusion means, and 13 is a radial metal reinforcing layer formed by C-shaped strips or Z-shaped dyeing. Reference numeral 4 denotes an axial metal reinforcement layer formed by wrapping a large number of flat strips around the outer periphery of the metal reinforcement layer 13 by means of a bitch; 15, the metal reinforcement layer 1 is formed by extrusion means;
An external plastic jacket is formed around the outer periphery of 4.

These components are the same as those described in the prior art.

In one embodiment of the present invention, in the high-pressure flexible tube having such a structure, an oil-immersed insulating layer 1G is interposed between the metal reinforcing layers 13 and 14.

The oil-impregnated insulating layer 16 is a thin layer formed by wrapping oil-impregnated insulating paper or oil-impregnated insulating cloth with tape,
When seawater or the like comes into contact with this layer, the seawater is rapidly absorbed in the longitudinal direction of the layer due to capillary action.

When the oil-immersed insulating layer IB is made of oil-immersed insulating paper.

Its dielectric constant is approximately 3.7, and the capacitance between the oil-immersed insulating layers 18 is determined by the following equation.

C= (gF/km)18! Ln(D
Meeting 2t)/.

In the above formula, ε is the dielectric constant, D is the outer diameter of the layer below the oil-immersed insulating layer IB, and t is the thickness of the tape constituting the oil-immersed insulating layer 1B.

As a more specific example, if the outer diameter of the metal reinforcing layer 13 made of C-type dyeing is 130 mm, and the tape thickness of the oil-immersed insulating layer 16 is t = 0.8 mm, then C is as follows: Become.

3.7 C = = 16.8 (pF/km) 18 sentences - 31 6113゜When the capacitance is as above and the total length of the high-pressure flexible tube is about 100~toooo long, the normal Changes in capacitance can be easily measured using a capacitance measuring device.

Next, another embodiment of the present invention will be described with reference to FIG.

FIG. 2 shows an example of a static type high-pressure flexible tube.

In the embodiment shown in FIG.
An oil-immersed insulating layer 16 is formed on the outer periphery of 7, and the same metal reinforcing layer 17 as described above is further formed on the outer periphery.

Below, towards the outer circumference, external plastic jacket) 1
5. The iron wire armor device 8 and the seat floor 18 made of rubber or the like are sequentially formed.

The high pressure flexible tubes shown in both FIGS. 1 and 2 are used as described above.

Note that the oil-immersed insulating layer may be interposed between the metal reinforcing layer and the outer plastic.

At this time, when measuring changes in capacitance, seawater is used as one electrode, but the measurement accuracy is reduced due to the influence of the capacitance of the external plastic jacket, so an oil-immersed insulating layer is used. It is preferable that the metal reinforcing layers are interposed between adjacent metal reinforcing layers, and these metal reinforcing layers serve as both electrodes.

Effects of the Invention 1 As explained above, the high-pressure flexible tube according to the present invention has an oil-immersed insulating layer interposed between the metal reinforcing layers or between the metal reinforcing layer and the external plastic jacket for detecting changes in capacitance. Therefore, by monitoring changes in capacitance through the oil-immersed insulation layer, pipe breakage accidents can be detected at an early stage and emergency measures can be taken before a major accident occurs. can.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing one embodiment of the high-pressure flexible tube according to the present invention, Fig. 2 is a sectional view showing another embodiment of the same, and Fig. 3 is a conventional high-pressure flexible tube. FIG. 12III111 Internal plastic pipe 13 @... Metal reinforcing layer 14... Metal reinforcing layer 15... External plastic jacket 16... Oil-immersed insulation layer 17, fist, metal reinforcing layer Agent Patent attorney Yoshio Saifuji No. 1 Figure 2

Claims (1)

[Claims] In high-pressure flexible tubes in which a metal reinforcing layer is provided between the inner plastic tube and the outer plastic jacket,
A breakage detection type high-pressure flexible tube characterized in that an oil-immersed insulating layer for detecting changes in capacitance is interposed between metal reinforcing layers or between the metal reinforcing layer and an external plastic jacket.