JPH03265787A - Connection structure for inner/outer surface corrosionproof metallic pipe - Google Patents

Abstract

PURPOSE:To improve anticorrosion and pullout resistance by surrounding a corrosionproof metallic pipe with an annular cap, and bonding the cap with the metallic pipe by an adhesive, and installing a packing between a joint and the cap, and locking the cap by the locker attached to the joint. CONSTITUTION:A joint 1 is equipped with flanges 12 at both ends on the outer surface. For an inner/outer surface corrosionproof metallic pipe 2, the inner surface and outer surface of the metallic pipe 21 are covered with synthetic resin layers 22a and 22b. The top 20 of the corrosionproof metallic pipe 2 is surrounded by the annular cap 3 having an outer tube 3a and an inner tube 3b, and the annular cap 3 and the corrosionproof metallic pipe 2 are bonded together by an adhesive 4. Furthermore, a packing 5 is installed between them, and the annular cap 3 is locked by the locker 6 attached to the end of the joint 1. As a result, the contact face is preserved stably, and excellent pullout resistance is secured, and also anticorrosion is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industry> 2. Field of Application The present invention relates to a connection between internal and external corrosion-resistant metal pipes whose inner and outer surfaces are coated with an anti-corrosion layer.

<Prior Art> In metal pipes, for example, steel pipes, a watertight coating layer such as a synthetic resin layer is provided on the inner surface of the pipe in order to protect the inner surface from corrosion from transport fluid. For the connection of such internally corrosion-protected metal pipes,
A screw-type connection is used, and in this case, synthetic resin is injected into the screw-type metal fitting body (made of malleable cast iron) 1' to prevent corrosion of the metal surfaces on the pipe tips. A putty-like sealing material 5' is placed between the core 3' and the joint body 1', and the pipe end 2' is screwed into the joint body 1'. As the process progresses, it is necessary to bring the metal surface air on the pipe tips into close contact with the putty-like sealing material 5', or as shown in Fig. 3 B, the flanged core 30'
is inserted into the tip of the tube, and a molded sealing material 5' is loaded between the flange 31' and the tube end surface, and the molded sealing material 5'
is in contact with the inner step surface 11'' of the joint body 1', and as the pipe end is screwed into the joint body, the metal surfaces of the pipe tips are embedded in the molded sealing material 5'. It is being done.

<Problem to be Solved> By the way, depending on the usage environment of the corrosion-proof metal pipe mentioned in 1., it is necessary to coat the outer surface of the metal pipe with a corrosion-proof layer, for example, a synthetic resin layer. However, such a metal pipe with corrosion protection on the inside and outside,
When connecting by screwing the same way as with the internal and external corrosion-protected metal pipes mentioned above, it is difficult to avoid the occurrence of excess threads due to variations in the amount of screwing due to variations in pipe diameter, a phenomenon unique to the screwing method, and corrosion occurs from this location. It is easy to lose the technical significance of providing corrosion protection on the outer surface of the metal pipe.

Therefore, it is inappropriate to use the screw-in method used for connecting the inner-corrosion-protected metal pipes in connection of the above-mentioned inner- and outer-corrosion-protected metal pipes, and a connection method for the inner- and outer-corrosion-proof metal pipes other than the screw-in method is to be developed. There is a need.

Connection methods other than the screw-in method include the adhesive method and the packing method, but the ordinary adhesive method (TS
With the packing method, it is difficult to protect the metal surfaces of the tube tips from corrosion against the transport liquid, and in particular, with the packing method, it is difficult to guarantee sufficient pull-out strength, and it is difficult to protect steel pipes used for transporting pressurized fluids. There is a safety problem when used for connection.

In view of the above, an object of the present invention is to provide a non-threaded metal tube with corrosion protection on the inner and outer surfaces, which can reliably protect the metal surfaces of the tube tips against transport liquid and also ensure sufficient pull-out strength. The purpose is to provide a connection structure.

Means for Solving the Problems> In the connection structure of the inner and outer surface corrosion-resistant metal tube according to the present invention, the tip of the inner and outer surface corrosion-resistant metal tube whose inner and outer surfaces are coated with an anticorrosive layer is connected to the outer cylindrical portion and the inner surface. between the inner peripheral surface of the outer cylinder part of the cap and the outer peripheral surface of the corrosion-proof metal tube on the inner and outer surfaces, and between the outer peripheral surface of the inner cylinder part of the cap and the inner peripheral surface of the corrosion-proof metal tube on the inner and outer surfaces of the cap. A packing is attached between the inner circumferential surface of the joint that has received the tip of the anticorrosive metal pipe with an annular cap and the outer circumferential surface of the outer cylinder of the annular cap, and the joint end This configuration is characterized in that the end of the outer cylindrical portion of the annular cap is locked to a locking tool attached to the ring.

<Explanation of Examples> Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is an explanatory diagram showing one embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a joint, which has an annular convex portion 11 at the center of the inner surface and flanges 12 at both ends of the outer surface. 13 is a packing mounting groove provided on the inner peripheral surface of the joint 1. Reference numeral 2 denotes a metal tube with anti-corrosion inside and outside surfaces, and the inner and outer surfaces of the metal tube 21 are coated with synthetic resin layers 22a and 22, respectively. Reference numeral 3 denotes an annular cap, which has an outer cylindrical portion 3a and an inner cylindrical portion 3, and surrounds the tip portion 20 of the inner and outer surface corrosion-proof metal tube 2. An adhesive 4 is used to bond between the inner circumferential surface of the outer cylindrical portion of this annular cap 3 and the outer circumferential surface of the corrosion-proof metal tube on the inner and outer surfaces, and between the outer circumferential surface of the inner cylindrical portion of the same cap 3 and the inner circumferential surface of the anticorrosive metal tube on the inner and outer surfaces. It is. 5 is a packing installed between the packing attachment fM] 3 of the joint 1 and the outer peripheral surface of the outer cylinder portion 3a of the annular cap 3. Reference numeral 6 designates a locking tool having a flange 61, which is connected to the flange 12 at the end of the joint with a pin 62, and whose tip is locked to the end surface of the outer cylindrical portion 3a of the annular cap 3. be.

Any suitable material can be used for the above-mentioned fitting (■) as long as it has the mechanical strength to withstand internal pressure and piping stress.
Hard thermoplastic resin, thermosetting resin, hook iron, gunmetal, iron, etc. can be used.

The inner and outer corrosion-resistant metal pipe 2 may be made of a steel pipe whose inner and outer surfaces are coated with a vinyl chloride layer. For example, a vinyl chloride dupe is adhered to the inner surface of the steel pipe with an adhesive, and the outer surface of the steel pipe is coated with vinyl chloride by extrusion. can use things.

The annular cap 3 includes vinyl chloride, polyethylene,
Polypropylene, rubber, or metal tubes can be used, and the appropriate thickness is about 0.5 to 1.0 times the wall thickness of the inner and outer corrosion-proof metal tube 2.

In order to assemble the connection structure of the above-mentioned inner and outer corrosion-resistant metal tubes, first, the locking tool 6 is inserted into the inner and outer corrosion-resistant metal tube 2, and then it is glued to the inner and outer surfaces and the 4 surfaces of the tip of the inner and outer corrosion-resistant metal tube tip 20. The agent 4 is applied, and immediately after this application, the inner and outer corrosion-proof metal tube tip 20 is press-fitted into the annular cap 3. In this case, the surfaces of the synthetic resin layers 2a and 2 on the inner and outer surfaces of the anticorrosive tube tip 20 swell, and this swelling layer acts as a lubricant, so even if the length of the annular cap 3 is increased to a certain extent, the above Press-fitting of the anticorrosive metal tube tip 20 into the annular cap 3 is easy. In particular, if the annular cap 3 is also made of synthetic resin, the adhesive surface of the annular cap 3 (inner circumferential surface of the outer cylindrical portion 3a and outer circumferential surface of the inner cylindrical portion 3?) will also swell. As a result, press-fitting can be performed more easily.

Next, after drying the adhesive, the tip portion 20 of the anti-corrosion metal pipe with the annular cap 3 is pressed onto the joint 1 with the packing 5 attached, and then the anti-corrosion metal pipe 2 is pulled through the pipe 2 in advance. The locking tool 6 is pulled back, and the flange 61 of the locking tool 6 and the flange 12 at the tip of the joint are connected with the bolts 1 to 62, and the work is completed.

In the above, the pulling force F applied to the anti-corrosion metal pipe 2 acts on the locking tool 6, the bolt nuts 1 to 62, and the joint 1 through the annular cap 3, and the annular cap 3 and the tip end of the anti-corrosion metal pipe 2
A shear stress τ acts on the adhesive interface with 0 as a reaction force to the pulling force, and if the area of the adhesive interface is deviated from A, then τ=F/A. The bonding area is determined based on the pulling force, bonding strength, etc., but it needs to be considerably wide considering safety, and therefore the length of the annular cap 3 needs to be considerably long. As described above, even if the annular cap 3 is made longer, it is easy to attach the annular cap to the anticorrosive metal tube tip 20.

In FIG.
The gap C between the tip of the pipe and the annular convex portion 11 on the inner surface of the joint serves to absorb thermal expansion and contraction of the corrosion-resistant metal tube, and the gap size is usually 3''-5 mm.

The present invention is not limited to the above-mentioned straight-line connection;
It can also be applied to type connections, connections between internal and external corrosion-resistant metal pipes and different types of pipes, etc.

Further, as for the locking tool, as shown in FIG. 2, a screw thread 15 may be carved on the inner surface of the end portion of the joint l, and the locking tool 6 may be screwed into the threaded thread 15.

<Effects of the Invention> The connection structure of the inner and outer corrosion-resistant metal pipes according to the present invention has a two-way configuration, and both the inner and outer peripheral surfaces thereof are in contact with the tip of the inner and outer corrosion-resistant metal pipes. The annular cap is attached with adhesive, and the contact area between the annular cap and the tip of the anti-corrosion metal tube can be widened due to the adhesion of the inner and outer circumferential surfaces, so that the above-mentioned adhesion is prevented under the pulling force acting on the anti-corrosion metal tube. The shear stress on the surface can be sufficiently reduced, the contact surface can be held stably, excellent pull-out strength can be guaranteed, and the metal surface at the tip end of the corrosion-proof metal tube can be reliably protected from corrosion by the annular cap.

In addition, since the packing is attached between the annular cap and the joint, it is possible to avoid applying pressure directly to the outer anti-corrosion layer of the anti-corrosion metal pipe with the packing, and prevent the outer anti-corrosion layer from becoming sag or damaged due to localized pressure. Can be stopped well. Furthermore, since there is no need for troublesome thread cutting work on site, the connection work is simple.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention, FIG. 2 is an explanatory diagram showing separate locking tools used in the present invention, and FIGS. 3A and 3B are explanatory diagrams showing conventional examples, respectively. It is a diagram. DESCRIPTION OF SYMBOLS 1... Fitting, 2... Corrosion-proof metal tube inside and outside, 20... Tip of corrosion-proof metal tube inside and outside, 3... Annular cap, 3a...
Outer cylinder part of the annular cap, 38... Inner cylinder part of the annular cap. 4... Adhesive, 5... Packing, 6... Locking tool.

Claims (1)

[Claims] The tip of an inner and outer corrosion-proof metal tube whose inner and outer surfaces are coated with an anti-corrosion layer is surrounded by an annular cap having an outer cylinder part and an inner cylinder part. The outer circumferential surface of the anti-corrosion metal tube is bonded to the outer circumferential surface of the anti-corrosion metal tube, as well as the outer circumferential surface of the inner cylindrical part of the cap and the inner circumferential surface of the anti-corrosion metal tube on the inner and outer surfaces are bonded with adhesive. Make sure that the packing is installed between the inner peripheral surface of the joint and the outer peripheral surface of the outer cylinder part of the annular cap, and that the outer cylinder end of the annular cap is locked to the locking tool attached to the end of the joint. Features a connection structure of internal and external corrosion-resistant metal tubes.