JPS5881522A - Lined pipe line and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a lined pipeline having high grade of fitting and compressive residual stress over the whole length by joining lined pipes and outer pipes independently by joints, applying an expanding liquid pressure in the lined pipes to expand them in a body with outer pipes, and removing the expanding liquid pressure at a specified diameter. CONSTITUTION:Liened stainless steel pipes 3... of a specified length are connected through welded joint 5... to set the length of a pipeline. On the other hand, unit outer pipes 2... made of carbon steel of set length to which flange joints 5' are formed by welding are fitted to the outside of connected pipes 3..., and connected and fastened by bolts and nuts. Next, a valve 6 installed at an end of the pipes 3... is closed and pipe expanding liquid (water) is put in the pipes 3... under pressure. The whole length of pipes 3... is expanded together with pipes 2 and water pressure for expanding is stopped before yielding of pipes 2.... The valve 7 is then closed and a valve 6 is opened, and the expanding water in the pipes 3... is removed. The pipes 3... are contracted in a body, and fastened over the whole length. Thus, a lined pipe line 1 to which compressive residual stress is given, in joint parts 5... as well as general parts, over the whole length is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The disclosed technology belongs to the technical field of full-length tension-strength fitting of tactile lined pipelines used for nuclear power piping and the like.

Therefore, the invention of this application relates to a lined pipeline in which the inner and outer pipes of a predetermined length of pipeline are joined and connected independently of each other, and then the inner and outer parts are tightly fitted together at once, and the production thereof. This relates to a method in which the operations and positions of the welded joint of the lining pipe and the joint of the outer pipe are completely independent of each other, and hydraulic pressure is applied to expand the inside of the lining pipe at a predetermined length of the pipeline to cause the pipe to yield. This relates to a lined pipeline that is plastically deformed to increase the diameter integrally with the outer pipe to remove the pipe expansion hydraulic pressure at a predetermined diameter, thereby creating a high degree of fit and compressive residual stress over the entire length O, and its manufacturing method. It is.

As is well known, nuclear couplant piping, oil transmission pipes, etc. must have corrosion resistance in addition to pressure resistance and heat resistance due to the conditions of transporting corrosive fluids. Also uses lined pipelines with a corrosion-resistant inner pipe inside a pressure- and heat-resistant outer pipe.

By the way, there is a limit to the length of the unit pipe that is a component of the pipeline due to problems with the manufacturing equipment at the manufacturing factory and transportation restrictions, so when assembling it on site, it is recommended to use a flange joint or a welded joint. Joint connections involving welding are often adopted from the viewpoints of sealing reliability, work speed, and low cost.

On the other hand, in order to prevent corrosion-resistant lined pipelines from implosion, cranking, and stress corrosion cracking during operation, it is necessary to apply compressive residual stress to the lined pipe and make it a tight fit. It is.

By the way, as shown in FIG. 1, the conventional lined pipeline 1 includes, for example, a unit outer pipe 4 in which a unit outer pipe 2 made of carbon steel is hydraulically expanded with a unit lining 3 made of stainless steel.
For example, a predetermined pipeline length is achieved by joining and connecting on-site through a butt weld joint 5, but as shown in Figure 2, tensile residual stress is formed near the weld joint 5, and compressive residual stress is generated in the general part Despite this, there was a drawback that stress corrosion cracking occurred during operation.

To deal with this, there is a technique such as spraying cold water on the welded joint 5, but it has the drawback that the work for each welded joint is extremely cumbersome and has poor workability, and there is also the problem that heat management is extremely troublesome. there were.

In view of the problems of the lined pipeline itself and its manufacturing technology based on the above-mentioned American technology, the purpose of the invention of this application is to have the lined pipe and the outer pipe have mutually independent zero-joints, so that the length of the pipeline can be adjusted. Expanding hydraulic pressure is applied to the lining tube to plastically deform it and increase its diameter together with the outer tube.After the expanding hydraulic pressure is removed, the outer tube elastically returns to achieve a high degree of fit over the entire length, and to reduce compressive residual stress along the entire length. The purpose of this paper is to provide a lined pipeline that has been given a problem and a method for manufacturing the same.

The structure of this IMLli invention in accordance with the above-mentioned purpose is to connect the unit lined pipes sequentially through welded joints along the pipeline length, and on the other hand, to connect the unit lined pipes to the outside of the lined pipes through welded joints. Separately and independently, the positions of the inner and outer pipe joints are made independent through predetermined joints, and the pipeline lengths are connected in the same way, and in this state, pipe expansion hydraulic pressure is applied to the entire length of the lined pipe to expand it along the stress-strain curve and cause it to yield. The tensile residual stress at the welded joint of the lined pipe is eliminated by plastic deformation, and the pipe is expanded at the set diameter by removing the hydraulic pressure to achieve uniform elastic contraction of the entire length of the outer pipe. It compresses the lined pipe and applies compressive residual stress not only to the general parts but also to the welded joints, and provides a high tight fit and compressive residual stress to prevent stress corrosion cracking and cracking during operation. The gist of this is that implosion can be prevented.

Next, an embodiment of this first invention will be described below with reference to FIG. 6 and subsequent drawings. Note that the same parts as in FIG. 1 will be explained using the same reference numerals.

In the embodiment shown in Figs. 6 and 7, as shown in Figs. The pipeline is configured to be connected and connected (.

Therefore, as described above, a tensile residual force of one core is formed in the weld joints 5, 5, . . . .

On the other hand, the carbon steel unit outer tubes 2, 2... of a predetermined length with flange joints 5' welded in advance are connected by externally inserting the connecting lining tubes 3, 3... through bolts and nuts. We will become closer together.

In addition, at this stage, the inner diameter O of the outer tube 2 and the outer diameter I of the lining tube 3 are set so that the former diameter is increased so that they can be layered, and the unit lengths and joint positions of both are completely independent of each other. It is.

In this way, when the unit outer pipes 2, 2..., unit lining pipes 3, 3... are connected to the length of the set pipeline 1, one of the lining pipes 2, 2... The attached valve 6 at the end is closed, the other 60,000 pulp 7 is connected to the bong 7081, and the lining pipes 3, 3, etc. are supplied with tap water as a pipe expansion liquid, and then the hydraulic jack 9 is used to fill the lining pipes 3, 3, . Apply pressure under the pipe expansion water to the pipe expansion water.

Therefore, as shown in Fig. 5.6.7, the lining pipe 2 is
The tube expansion force is applied all at once, and the diameter D is on the horizontal axis and the stress F is on the vertical axis.
According to the stress-strain curve, the lined pipe 3.3... has an outer diameter of ■
The diameter increases as shown in A, yields, and expands together with the outer tube 2 having an initial inner diameter O, and the water pressure for expanding the tube is stopped before the outer tube 2 yields at the set diameter D'.

During this time, as shown in Figures 5 and 6 (the lining pipes 3, 3...
Due to the yield expansion of the welded joints 5, 5, the aforementioned tensile residual stress applied at the time of formation is eliminated.

Therefore, when the three-way valve 7 is closed, the valve 6 is opened, and the expansion water in all the inner tubes 3, 3, etc. is drained to remove the expansion water pressure, the outer tube 2. 2... is elastically returned and contracts as shown in 4', and the lined pipes 3, 3...
is integrally contracted (like a cylindrical pipe), and a fitting allowance ΔD is obtained to securely fit the entire length, and at the same time, not only the general part but also the welded joint 5, 5... However, the compressive residual stress I over the entire length
J5 will be granted.

This completes the manufacturing work for the lined pipeline 1, but in the obtained lined pipeline 1, the lined pipes 3, 3...
・Applying compressive residual stress (this prevents stress corrosion cracking from occurring during full-length operation, and the tight fit prevents cracking and implosion from occurring.

Thus, in the embodiment described above, the outer tubes 2, 2... are connected via flange joints 5', 5'..., but in the embodiment shown in FIG. Due to the independent connection of the tension pipes 3, 3... through the welded joints 5, 5..., the outer pipe 2
, 2 . . . are also independently extrapolated by sliding and connected by welded joints 5, 5 .

Then, the connection of the pipeline long lining pipes 3, 3...
After the connection of the outer tubes 2, 2... is completed, hydraulic expansion, yielding, plastic diameter increase, elastic return of the outer tube, etc. are performed in the same steps as in the above-mentioned embodiment.
Therefore, there are no effects such as full-length tight fitting of the inner tubes 3, 3... to the outer tubes 2, 2..., application of compressive residual stress, prevention of cracking, implosion, prevention of stress debris corrosion, etc. are the same.

It should be noted that the embodiments of the invention of this application are of course not limited to the above-mentioned embodiments. For example, the embodiments of the invention of this application are not limited to the above-mentioned embodiments. Various aspects can be adopted.

As described above, according to the invention of this application, in a lined pipeline, although a large number of unit lined pipes are connected by welded joints, the outer pipe ζ In addition, compressive residual stress is applied not only to the crotch but also to the welded joint, so it goes without saying that cracking and implosion will not occur during operation, and stress corrosion will not occur. An excellent effect is achieved in that no cracking occurs.

Moreover, since the tightness and compressive residual stress are uniform over the entire length of the pipeline, the quality and precision of the products as a pipeline are improved.

In this manufacturing method, the unit lining pipe and the outer pipe can be connected independently of each other, and the unit lengths can also be connected with joints under mutually independent conditions, so the connection work can be carried out with extremely high efficiency. Furthermore, since only the connection work is required, accuracy is high and quality control is also advantageous.

In addition, after connecting the lining pipe and the outer pipe along the pipeline length, the entire length of the lining pipe is filled with expansion liquid and expanded all at once, so that the expansion, yielding, and plastic deformation of the lining pipe occur simultaneously over the entire length. The diameter of the outer tube is increased integrally with the outer tube, and after expanding the tube, the hydraulic pressure is removed and the entire length of the outer tube is simultaneously elastically contracted to fit tightly and compressive residual stress is applied. Not only does it have an excellent effect, but it also expands the entire pipeline length in one pass, requiring only one tube expansion process, which is coupled with increased efficiency due to reduced man-hours, reduced power costs, and improved safety. It is possible to expand pipes on-site, and has excellent effects that can be matched to on-site plant conditions.

Furthermore, the tensile residual stress that inevitably occurs in the joints when the lined pipes are disassembled during the connection process is also eliminated during the pipe expansion and contraction process, and compressive residual stress is automatically removed over the entire length in the tight fitting process, just as in the crotch area. There are also excellent effects that can be achieved.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram of a lined pipeline based on the prior art, Fig. 2 is an explanatory diagram of residual stress in the welded joint, and Fig. 6 and subsequent figures are detailed explanatory diagrams of the invention of this application. The figure is 1
Fig. 4 is an explanatory diagram of the manufacturing process of the embodiment, Fig. 4 is an end view of Fig. 6 IV-IV, Fig. 5 is an explanatory diagram of tube expansion, Fig. 6 is Fig. 5 Vl-Vl
An end view, FIG. 7 is an explanatory diagram of stress strain curves, and FIGS. 8 and 9 are explanatory diagrams of manufacturing steps of other embodiments. 3...Unit lined pipe, 5...(welded) joint, 2
...unit outer pipe, 5'...fitting, 1...pipeline

Claims (2)

[Claims] (1) In a predetermined length tight-fitting lining pipeline of a unit lining pipe jointed and internalized by a joint connection of a unit outer pipe, the joints of the lining pipe and the outer pipe are in mutually independent positions,
The lined pipeline is characterized in that the lined pipe and the outer pipe are connected with a high degree of fit along the entire length, and compressive residual stress is applied to the lined pipe over the entire length. . (2) The entire length of a pipeline with a lined pipe inside the outer pipe (method for manufacturing a lined pipeline in which the lined pipe is tightened to the outer pipe all at once via hydraulic expansion) In this method, unit lined pipes are connected to a predetermined length via a welded joint, and unit outer pipes are externally connected to a predetermined length independently via a joint, and the lined pipe of the set length pipeline is hydraulically expanded. After plastically deforming and increasing the diameter together with the outer tube, the tube expansion hydraulic pressure is removed and the outer tube is elastically contracted in diameter to tightly fit the inner tube to the outer tube over the entire length and apply compressive residual stress along the entire length. A method for manufacturing a lined pipeline, characterized in that the lined pipeline is made to