JP2001099391A - Pipe joint part corrosion preventive structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pipe joint corrosion preventive structure in a polyethylene sleeve construction method capable of being easily executed even at a watering place and always obtaining a uniform execution result. SOLUTION: This structure is constituted by coating outside faces of joint parts 2, 3 of a metallic pipe in which a corrosion prevention is performed for a pipe part 1 by a corrosion preventive layer 5 of polyethylene coating or a polyethylene sleeve with an extendable sheet 7 into which corrosion suppressing agent is impregnated, further coating the outside face of the extendable sheet 7 with a rubber sheet 8 provided with an adhesive layer on an inside face and winding, fastening and fixing both ends of a shaft direction on the outside face of the rubber sheet 8 with a fastening tool 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corrosion prevention structure for a pipe joint.

[0002]

2. Description of the Related Art Conventionally, when metal pipes such as cast iron pipes are buried underground, polyethylene-coated pipes or pipes are used for the purpose of eliminating contact with corrosive soil and the influence of groundwater to prevent corrosion and electrolytic corrosion. A method of burying a tube covered with a polyethylene sleeve is known.

[0003] Here, the polyethylene coating means that a polyethylene tape extruded from a T-die is wound around an outer periphery of a metal tube such as a heated ductile cast iron tube with or without an adhesive, while being partially wrapped and wound around the entire periphery. It refers to a coated one, or a polyethylene sleeve extruded into a cylindrical shape from a round die to cover and adhere to the outer circumference of the metal tube.

[0004] The polyethylene sleeve method refers to a method in which a polyethylene sleeve having a large diameter is externally fitted to the outer periphery of a metal pipe such as a ductile cast iron pipe, and a surplus portion is wound around the outer circumference of the pipe to form a corrosion-resistant coating. By the way, the pipe joint portion of a pipe line covered with polyethylene coating or a polyethylene sleeve is usually covered with a polyethylene sleeve, but since the outer diameter changes at the receiving portion, a polyethylene having a large diameter that can cover the pipe joint portion. There is a problem in that a sleeve is used, and the treatment of a polyethylene sleeve that is loose on the outer periphery of the tube becomes troublesome.

In order to solve such a problem, the outer periphery of the pipe other than the joint portion is covered with another joint and another sleeve, and the joint portion is covered with a heat-shrinkable polyethylene sleeve, which is heated and shrunk to provide corrosion protection. There are cases.

[0006]

In the above method, a joint portion having an enlarged diameter is covered with a heat-shrinkable polyethylene sleeve without gaps, and a tube portion is coated with a polyethylene coating or the like.
Since it is covered with a polyethylene sleeve that matches the pipe diameter,
The sleeve does not loosen on the outer circumference of the pipe and the joint,
The construction is easy and the waterproofness is good.

However, the heat shrinkage of the polyethylene sleeve requires heating with a burner or the like. However, in a stagnant environment or an outflow environment of groundwater, it is difficult to heat the polyethylene sleeve by the burner due to the cooling action by water. There was a problem that the shrinkage temperature could not be reached. In addition, the heating must be performed slowly and uniformly, but there is also a problem that the work results tend to differ between individuals, so that the work results for each pipe joint tend to differ.

Further, a polyethylene sleeve having a large shrinkage rate must be used in order to cover the outer surfaces of the receiving port and the insertion port having a difference in outer diameter without any gap, and there is a problem that the polyethylene sleeve becomes expensive. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to obtain a pipe joint corrosion-resistant structure that can be easily constructed even in a water place and that can always obtain uniform construction results.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a metal pipe in which a pipe is coated with a polyethylene coating or a polyethylene sleeve, and the outer surface of the joint is covered with a stretch sheet impregnated with a corrosion inhibitor. The outer surface of the elastic sheet is further covered with a rubber sheet provided with an adhesive layer on the inner surface, and both ends in the axial direction of the outer surface of the rubber sheet are fixed by tightening with a fastener.

Therefore, according to the present invention, since the heat-shrinkable polyethylene sleeve is not used for coating the pipe joint portion, it can be easily installed even in a water place. In addition, since the pipe joint portion is double-coated with the elastic sheet impregnated with the corrosion inhibitor and the rubber sheet, it is strong against impact, and has good corrosion and waterproof performance.

[0011]

Next, an embodiment of the present invention will be described. FIG. 1 is a cross-sectional view schematically illustrating a corrosion-resistant structure of a pipe joint portion according to an embodiment of the present invention, which is a slip-on type pipe joint including a receiving port and an insertion port. In FIG. 1, reference numeral 1 denotes a metal pipe (hereinafter referred to as a pipe) such as a ductile cast iron pipe, which has an insertion port 2 at one end and a reception port 3 at the other end, and inserts the insertion port 2 into the reception port 3 as shown. It is connected by doing.

Reference numeral 4 denotes a spacer for reducing a step between the outer surface of the insertion port 2 and the end face of the receiving port 3, and is formed of styrene foam or the like. Reference numerals 5 and 5 denote corrosion-resistant layers made of polyethylene coating or polyethylene sleeve which cover the outer circumference of the pipe 1. The outer circumference of the pipe is coated or coated by the same method as the conventional method. A tightening member 6 is provided on the outer periphery of the pipe 1 except for the opening 3.
Are tightened.

A stretchable sheet 7 impregnated with a corrosion inhibitor is coated on the outer surfaces of the insertion opening 2 and the receiving opening 3 at portions not covered with the corrosion-resistant layers 5 and 5 made of the polyethylene coating or polyethylene sleeve. It is covered so as to partially overlap the end. Here, the corrosion inhibitor refers to a liquid or gel-like substance having a function of suppressing rusting or electrolytic corrosion of a metal tube by water, and a substance which does not dry and solidify is used. In addition to chromic acid and carbonate as these, oxygen, nitrogen,
Saturated and unsaturated heterocyclic compounds containing sulfur, high molecular alcohols, aldehydes, amines and their derivatives and amides, organic sulfonic acids and their derivatives, fatty acids and their derivatives, thioureas and their derivatives, thiazoles, quaternary ammonium Salts, organic sulfonium compounds, highly unsaturated cyclic and chain compounds, thioamides and thiosemicarbazides, polymer nitriles, mercaptans and sulfides,
There are sulfoxides and sulfones.

Further, as a passive film forming type, there is a nitrite used for a recirculating water absorption system such as a cooling tower of an internal combustion engine, a rectifier, a boiler or the like. In addition, NaOH, Na ₂ H
PO ₄ , Na ₂ O.nSiO, Na ₂ B ₄ O _{7 and the} like are used. Precipitating film type inhibitors include phosphates and silicates, which form insoluble phosphates and silicates with eluted metal ions. Calcium bicarbonate reacts with hydroxide ions generated by the cathodic reaction to form a calcium carbonate (CaCO ₃ ) precipitate film to protect it from corrosion.

Further, a water repellent such as pitch, tar, grease or a perolatam-based tape impregnated with these, or a metal soap is used. The stretchable sheet 7 is a mesh-shaped knitted or woven fabric made of synthetic or natural fibers impregnated with the corrosion inhibitor, and has a stretchability as large as possible.

A rubber sheet 8 provided with an adhesive layer (not shown) on the inner surface is externally fitted and adhered to the outer surface of the elastic sheet 7. As the material of the rubber sheet 8, the same rubber as described above can be used, but ethylene propylene rubber, butyl rubber, chloroprene rubber, fluorinated rubber, urethane rubber, etc., which are excellent in chemical resistance and wear resistance, are preferably used. You.

The pressure-sensitive adhesive layer in the above description refers to a thin coating layer made of a semi-fluid which is easily tackified due to viscosity, and may be a pressure-sensitive adhesive. As shown in FIG. 2, when wound around the joint portion, the remaining portion 8 a of the rubber sheet 8 makes the adhesive layers face-to-face adhere, and this portion 8 a is folded and wound on the outer surface of the pipe joint, and the outer surface is It is wound and fixed by such a tightening tool 9. Reference numeral 9a denotes a buckle of the tightening tool 9, which fastens the tightening tool 9 tightened in the direction of the arrow.

The axial position 9b to be tightened is
As shown in FIG. 1, it is located at a position covering the tightening portions 6, 6 of the polyethylene sleeve 5 on the outer surface of the pipe 1, and the pressure-sensitive adhesive layer is pressed to prevent water from entering the joint portion. Next, an assembled state of this embodiment will be described. First, as shown in FIG. 3, the insertion port 2 of the metal tube 1 provided with the corrosion-resistant layers 5 and 5 made of polyethylene coating or polyethylene sleeve is inserted into the receiving port 3 and connected.

When the anticorrosion layers 5 and 5 are covered with polyethylene sleeves, the insertion holes 2 of the metal pipes 1 whose polyethylene sleeves are tightened by the fasteners 6 and 6 are inserted into the receiving holes 3 and connected. Next, the spacer 4 is arranged at a step between the outer surface of the insertion opening 2 and the end surface of the receiving opening 3. Then, a stretchable sheet 7 impregnated with a corrosion inhibitor is placed over the entire outer periphery of the joint. Since the elastic sheet 7 has a large elasticity, it may be a joint having a complicated outer shape, and expands and contracts according to its shape.

At this time, the covering of the stretchable sheet 7 is
(1) It is put on a corrosion-resistant layer 5 such as a polyethylene coating or a polyethylene sleeve on the outer surface so as to partially overlap. Thereafter, as shown in FIG. 4, a rubber sheet 8 provided with an adhesive layer on its inner surface is covered and wound so that the end portions of the polyethylene coating or the tightening portions 6, 6 of the polyethylene sleeves 5, 5 are covered.

As shown in FIG. 2, the surplus rubber sheet 8a is overlapped so that the inner adhesive layers adhere to each other. Then, the excess rubber sheet 8a is overlapped along the outer surface as shown in FIG. 2, and tightened with a tightening tool 9 such as a band. With the above, the construction of the pipe joint corrosion prevention structure is completed, and the pipe is buried with backfilled earth and sand.

At this time, since the elastic sheet 7 impregnated with the corrosion inhibitor of the pipe joint portion is protected by the rubber sheet 8, even if the injected earth and sand hits directly, no break occurs and water tightness and water resistance are improved. Can be assured. The rubber sheet 8 has an inner adhesive layer adhered to the polyethylene coating or the polyethylene sleeves 5 and 5, and the excess part of the rubber sheet 8 is adhered to the adhesive layers and then folded and tightened by the fastener 9, so that the waterproof property is also improved. There is no infiltration of groundwater.

When the construction time of the conventional polyethylene sleeve method and the corrosion-resistant structure of the pipe joint portion of the present invention were compared, the construction time of the conventional heat-shrinkable tube was 20 to 30 minutes. In the case, 7 to 10 minutes and about 1 /
It turned out that it can be shortened to 3. In addition, the pipe joint of the present invention is immersed in a water tank filled with a 3% saline solution and repeatedly dried and wet in 24 hours for 3 months, and the cycle of dry and wet is repeated for 24 hours. After performing a waterproof test, the rubber sheet and the elastic sheet impregnated with the corrosion inhibitor were removed, and the pipe joint was observed.As a result, no water was immersed inside, and rust on the outer surface of the pipe naturally occurred. But was not observed.

[0024]

As described above, according to the present invention,
Since the pipe joint is covered without any gaps by a stretch sheet impregnated with a corrosion inhibitor, it becomes possible to coat the pipe joint closely without using a heat source like a heat-shrinkable tube.
In addition, since the metal surface is protected from corrosion by the corrosion inhibitor, construction can be performed easily and reliably even in a water place.

Further, the construction time can be reduced to one third as compared with the conventional polyethylene sleeve construction method, and work can be performed very quickly. As for the water stopping property, the double covering with the elastic sheet impregnated with the corrosion inhibitor and the rubber sheet having the inner surface adhesive layer has the effect of exhibiting the same or higher water stopping property as the conventional polyethylene sleeve.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is a sectional view showing an embodiment of the embodiment shown in FIG. 1;

FIG. 4 is a sectional view showing an embodiment of the embodiment shown in FIG. 1;

[Explanation of Signs] 1 pipe 2 insertion opening 3 receiving opening 4 spacer 5 polyethylene sleeve 6 fastening part of polyethylene sleeve 7 elastic sheet 8 rubber sheet 9 fastening tool

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroaki Shimizu 2-26-26 Ohama-cho, Amagasaki-shi, Hyogo F-term in Kubota Mukogawa Works (reference) 3H024 DA01 EA02 EA04 EC09 EE01 EF20

Claims (1)

[Claims] 1. A rubber in which the outer surface of a joint portion of a metal tube whose pipe portion is corroded with a polyethylene coating or a polyethylene sleeve is covered with an elastic sheet impregnated with a corrosion inhibitor, and the outer surface of the elastic sheet is provided with an adhesive layer on the inner surface. A pipe joint corrosion-resistant structure in which the rubber sheet is further covered with a sheet and both ends in the axial direction of the outer surface of the rubber sheet are fixedly fastened by tightening tools.