JPS60260789A - Method of welding and joining inner-surface lining steel 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 The present invention relates to a method for welding and joining lined steel pipes, which provides a joint that is excellent in strength and exhibits high performance in terms of corrosion resistance and wear resistance.

Initially, the lining steel pipes were joined by a round joint as shown in Figure 3, but this method cannot eliminate the risk of leakage and is virtually impossible to apply to underground piping. Therefore, in recent years, joining methods by welding have attracted attention, and various proposals have been made regarding such methods. Some representative examples are as follows.

1) As shown in Fig. 4, weld the joining member 0, which has a large diameter part and a small diameter part, to the outer surface of each end of the pipes (1) to be joined (1), and then weld them! (11(1) is placed facing each other with the lining layers (5) (5) in between, and the joining member 01) is a method of joining by butt welding the large diameter ends of 0υ. It is called a bridge type joint.

11) As shown in Fig. 5, an expanded tube portion is provided at each end of the pipes to be welded (1) (1) by butt welding with a reducer (A), and a heat insulating material is placed in the inner cavity of the expanded tube portion. A method of filling α■, finning (5), and butt welding the expanded tube parts together.

111) As shown in Fig. 6, the inner surface fining (5) is applied to the pipes to be joined (1) (1) leaving the required range at the ends, and after joining these two pipes by butt welding, By matching the heating means α to the unfined portion (5), a through hole Q6f! A method of performing repair lining by curing the injected resin.

IV) As shown in Fig. 7, the end of the pipe to be joined (1) (1) is expanded, and the expanded part αQ0 and inner surface are lined with a rust-proof metal plate αη (ring-shaped). ) After matching Ql19, butt weld the pipe ends, and then attach the rust-proof metal plate αη and the existing inner fining (5) (5)
Paint the gap 000 between.

However, all of these conventional methods have their own problems and are not practical enough. In other words, ■) In the method 1) shown in Fig. 4, the joining member aη is fixed to the outer surface of the pipe fl) (1) by so-called fillet welding, so the strength of the joining part is low. I have anxiety about this. In addition, although welding of the joining member 0ηαη is performed at a location away from the pipes to be joined (1) (1), the welding welding part is folded between the pipe ends at the pipe butting position, which is the lining part. (
5! i) There is still a risk of damage to (5a), and if the butt sealing properties of the finings in the same group are impaired, the fluid inside the pipe may leak to the outside, resulting in separation of the finings from the pipe ends and corrosion of the pipe itself. Become.

■) Method 11) shown in Fig. 5 involves cutting the inside of the expanded tube.

The adhesion between the heat material α■ and the fining (5) inside it, as well as the butt sealing property of the -F lining, are also poor, making it impossible to prevent leakage of the fluid in the pipe.

Even with method 111) shown in Fig. 6, it is actually difficult to apply repair fining after pipe joining, and the gluing of the repaired part is not reliable in terms of adhesion.

W) In the method of 1lv) shown in FIG. 7, painting the inner surface after joining the tubes is time-consuming, and the resulting coating is also poor in reliability.

<Objective of the Invention> The present invention has excellent strength, does not cause deterioration of the inner fining due to the effects of pipe joining welding, and exhibits performance comparable to that of the original pipe in terms of corrosion resistance and wear resistance. To provide a welding method for welding inner-lined steel pipes, which can stably obtain a joint portion with a lining, which requires no troublesome subsequent repair of the inner-surface fining, and which has a low cost.

<Structure of the invention> The gist of the present invention lies in the following (1) and (2).

■ Add an expanded tube to the end of the inner sheathed tube, insert a ring body into each of the two corrugated tube portions with an inner diameter approximately between that of the original tube, and weld one end of the ring to the inner surface of the sloping portion of the expanded tube. When the two wave tube sections are butted, the ring bodies face each other at a certain distance in the tube axis direction from the abutting position of the expanded tube section, and have a predetermined distance between them and the inner surface of the expanded tube section. Then, a lining is applied to each inner sheathed tube so as to continuously cover the inner surface of the original tube part, the inner surface of the ring body, and the release side end thereof, and then the release of both ring bodies is applied. With the side ends aligned with each other with the lining layer in between, the G parts of both waves are butt-welded and joined together, and then resin is injected into the space between the expanded tube part and the ring body through the injection hole prepared in advance. A method characterized by filling the injection hole with a plug and plugging the injection hole.

■ In method (■) above, only one ring body is used, and the ring body is inserted and installed only in the expanded tube part of the tube to be joined on one side, and its tip is placed correspondingly on the sloped part of the expanded tube part on the other side. A method in which both wave tube sections are butt welded together.

In other words, the method of the present invention is an improvement on the so-called bridge type joint method that uses a reducer-like joining member αη as shown in FIG. Instead of attaching the fillet bath to the surface, we decided to provide an enlarged part at the end of the pipe and separately provide a ring body inside the enlarged part as a material for forming the inner surface of the pipe. Shift it in the direction of the pipe axis from the joint welding position,
In order to avoid the negative effects of welding, ■Furthermore, in order to prevent the fluid inside the pipe from leaking from the joint of the lining, we filled the space between the expanded pipe part on the outside of the ring body with resin.
The above are some of the major improvements.

<Example> Hereinafter, the joining method of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a vertical cross-sectional side view of the upper half showing one of the joining methods of the present invention, and this figure shows a joint portion that has been joined. In the figure, (1) (1) is the pipe to be joined, (21 (2) is the expanded part attached to the joined end, and (3) and (8) is the original part of the pipe to be joined (other than the expanded part). (4) is the ring body, (5) is the resin lining, and (6) is the filled resin.

That is, in the method of the present invention, pipes are joined as follows.

■ First, provide an expanded tube portion (2) (2) to the end of the W (t) (1) to be joined.As a means for providing the expanded tube portion, use a structure in which the diameter of the tube expands and contracts using hydraulic pressure, etc. Generally, the core metal is set inside the tube end and expanded by pushing.In this case, the tube expansion rate and the length of the tube expansion section vary depending on the thermal conditions of use and tube conditions, but the tube expansion rate is generally 5 to 15. %
, the length of the expanding part (including the inclined part (2a)) is 150~aoo
A value of about m would be appropriate. Applicable to seamless pipes,
Any material such as electric resistance welded pipe may be used. In the case of electric resistance welded pipes, careful attention must be paid to seam annealing of the electric resistance welded portion, changes in tube length due to tube expansion, thinning, and roundness.

In addition to the tube expansion operation described above, a method using a reducer may be used as a method for providing the tube expansion portion. In the case of method 2, the reducer to be used should have the same inner and outer diameters as the inner and outer diameters of the pipe to be joined, and the reducer should be attached by butt welding to the end of the brass pipe. It is important to do so. This is an essential condition in terms of joint strength.

(2) Next to the expanded tube portions (2) (2), the ring bodies (3) (8') are inserted and fixed. Ring body (3)
(8') has an inner diameter of 0. ) is the same as or slightly larger than the inner diameter of the original tube part (4), the outer peripheral edge of one end (3a) is cut diagonally into a chamfer shape, and this surface (3b) is used as the expanded tube part.
Abut against the inner surface of the inclined part (Katada 2a) following the original tube part,
The end face (30) and the inner surface of the inclined portion are circumferentially welded from the inside to be fixed. The welded part (7) should be finished smooth with a rough finish.

Here, it is important that the lengths of the ring bodies (3) (+) (a) (1) are different from each other rather than being the same. In other words, when the two wave tube sections (21 (2) are butted together, the ring bodies (3) (3) are separated from the tube expansion section abutting position (4) in the tube axis direction so that they face each other at a certain distance. The distance between the ring bodies (3) and (8) is the distance between the folded portions (5a) and (5a)'e of the lining, which will be described later (specifically, 8 to 1 degrees).

In such a structure, the corresponding position of both ring bodies (indicated by the abutment position of the linings) is moved away from the expanded tube abutment position (8), and the lining (folded) part near the upper NlEB position (5゛Haraichi) It is important to ensure that the welding is not affected by the welding at the A position. Therefore, the position B is set at a location where welding caused by welding at the A position can be avoided.

Apart from using a set of ring bodies like this, there is also a method of using only one ring body. An example is shown in FIG. That is, the ring body (3) is attached to only one of the sealed tubes (υ) in the same manner as described above, and the ring body (3) F1 and both enlarged tube portions (21 (2) are abutted against each other and the other side to be joined Pipe (1
) are arranged so that they face each other with an interval between them to sandwich linings (5a) (5), which will be described later, on the inner surfaces of the inclined parts (2a).

In both cases of Fig. 1 and Fig. 2, the ring body (3) (8'
) or (3) and the expanded pipe portion (21(2)), a space (good) that continues in the circumferential direction is formed.

In addition, at least two holes (8) communicating with the space (goods) are provided in either of the pipe expansion parts (2+(2)).These are for injecting resin into the space (goods) after the pipes are joined. After resin injection, cut the taper thread and attach the plug (
Step 9) to make a stopper. Note that this drilling work may be performed before or after the attachment of the ring body.

■ Next, apply lining to the pipe to be joined in this way. In the case of Fig. 1, the lining (5) extends from the inner surface of the original tube part (4) to the inner surface of the ring body (3) for any pipe to be joined.
Furthermore, the ring is provided so that it is folded outward at the open end [3a] (hereinafter referred to as the tip) and folded back toward the outer surface so as to continuously cover the tip of the ring.

In the case of Fig. 2, the one with the ring body (3) is the same as above, but the other is the original pipe part (4), and the inclined part (2) of the expanded pipe part.
It is provided so as to cover up to the position facing the ring body in a). A ring-shaped collar 01 may be attached as a nutopper of the folded part (5b) on the ring body tip (3d) side of the lining. Note that any currently known lining resin may be used. For example,
Tar epoxy, epoxy.

Polyurethane fstomer, natural neoprene rubber.

These include polyethylene, PVC, nylon, etc.

The above steps are carried out in advance at the factory.

■ At the site, the expanded portions (2H2) of the pipes to be joined (1) (1) are butt-welded to each other. During welding, as shown in Figure 1, the inner ring body (3) (
8) Ring bodies (3) as shown in Figure 2.
) and the inner surface of the inclined part (2a) of the other side expanded tube part are positioned so that they sandwich and correspond to the lining (5a) (5a) or (5a) (5). At this time, the linings are made to have a tendency to come into pressure contact with each other so as to maintain sealing properties between the linings.

Even when such welding is performed, the folded portion (5a) of the lining is not affected by any displacement in the tube axis direction with respect to the welding position (6).

■ After welding is completed, the hole (
83 (8) is opened by removing the plug (9) (9), and resin is injected into the space (goods) from one of the holes to fill it.

In this case, it goes without saying that the other hole functions as an air vent. As the resin to be filled, a type that has an injectable viscosity and hardens at room temperature, such as a room temperature curing polyurethane resin, is used.

After resin injection, insert plugs (9) (9) into both holes (8) (8).
) is tightened and fixed, and the joining is completed.

<Effects of the Invention> According to the method of the present invention as described above, a joint having the following features and advantages can be realized.

1) It has excellent pressure resistance inherent to a welded structure, and can be buried underground, which is impossible with joints such as flange joints.

11) Unlike conventional bridge-type joints, the force in the pipe axis direction is not received at the fillet weld, and compared to bridge-type joints, it is much more resistant to external forces such as bending and tension.

111) The inner lining is not affected by pipe joint welding, and resin is filled around the O-ring body and between the tube expansion part as a member for forming the inner surface of the tube, so it is rather original in terms of corrosion resistance and wear resistance. Demonstrates performance that surpasses that of the pipe section.

Iv) Not only is it advantageous in terms of cost compared to conventional flanges and Victoriques, etc., but it is extremely easy to install on-site, as it only requires resin injection, which requires no special skills other than welding. It is.

■) It is easy to implement anti-corrosion measures on the external surface of the joint.

Therefore, the present invention greatly contributes to improving the joint performance of internally lined steel pipes, reducing the cost of fitting, etc.

[Brief explanation of the drawing]

Claims (2)

[Claims] (1) Provide an expanded section at the ends of the two steel pipes to be joined by expanding the pipe or attaching a reducer by butt welding, and attach a ring to each expanded section with an inner diameter approximately between that of the original pipe of the pipe to be joined. Insert the ring body and weld its one end to the inner surface of the inclined part of the tube expansion part, and when the expansion tube parts are abutted, the ring bodies are spaced a certain distance from each other at a required distance in the tube axis direction from the butt position of the expansion tube part. The inner surface of the original part, the inner surface of the ring body, and the open end thereof are continuously coated on such double-wave joint pipes, respectively. Then, the open ends of both ring bodies are butt-welded and joined to each other with the lining layer sandwiched between the open ends of the ring bodies, and then the injection holes prepared in advance are connected. Inject resin into the space between the tube expansion part and the ring body.
A method for welding and joining inner-lined steel pipes, characterized by filling the injection hole and plugging the injection hole. (2) Provide an expanded section at the ends of both steel pipes to be joined by expanding the pipe or attaching a reducer by butt welding, and make sure that the inner diameter of one of the expanded sections is approximately equal to the inner diameter of the original pipe of the pipe to be joined. One end of the ring body is inserted and its insertion end is welded to the inner surface of the sloped part of the pipe to be joined, and when the expanded pipe parts are abutted, the ring body is attached to the inner surface of the sloped part of the pipe to be joined on the other side as required. facing each other with an interval and forming a predetermined space between the inner surfaces of both widened back parts, and then the double-wave jointed pipe,
The one with the ring body continuously covers the inner surface of the original tube, the inner surface of the ring body, and the open end thereof, and the other one covers the inner surface of the original tube including the part of the slope facing the ring body. Then, with the ring body corresponding to the inner surface of the inclined part on the other side via the lining layer, the expanded pipe parts are butt welded and joined together, and then the pipe parts prepared in advance are A method for welding and joining inner-lined steel pipes, which comprises injecting and filling the space between the expanded pipe section and the ring body with resin through the injection hole, and plugging the injection hole.