JPS63123527A - Manufacture of crack arrester steel pipe - Google Patents

Abstract

PURPOSE:To easily form a crack arrester steel pipe without any restrictions by boring a penetrating hole toward width direction at the middle part of thick ness in longitudinal direction, inserting a steel in the hole, hot-rolling to a steel plate, then making it the pipe-like state by rolling up toward width direction and seamwelding both faced ends. CONSTITUTION:The one or plural holes penetrating toward width direction at right angle direction to the longitudinal direction at the middle part of thick ness in a part of the longitudinal direction of a slab 1 are bored. Next, the steel piece 3 having the same or different material as the slab 1 and cleaned surface is inserted and the opening ends thereof is seal welded. Next, after heating this slab 1, it is flatly spread toward longitudinal direction by the thick plate rolling mill under pressing condition without any metallurgical joining the inserted steel piece 3 with the base material 1, to make it the raw material steel plate 5. And, by a canmaking means, the raw material steel plate 5 is bent toward width direction, to form to the pipe-like state, which both side edges are faced, and by longitudinally seamwelded both the side edges, the crack arrester steel pipe 6 inserting an annular body 3'', which quasi-joins to the base material at the thick part in a part of axial direction is made.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a crack arrester steel pipe, particularly a crack arrester steel pipe in which an arrester is installed inside the pipe with a thick wall.

(Conventional technology) Pipelines for natural gas transportation, etc. have 100 to 300
Crack propagation in the longitudinal direction of the tube axis may occur due to unstable ductile fracture at a speed of m/sec.

For this reason, when constructing a vibrate line by sequentially butting and circumferentially welding steel pipes of a predetermined length, a so-called crack arrester steel pipe, which has the function of preventing the crack propagation, is inserted every few to tens of steel pipes. used.

The following types of tartar arrester steel pipes that have been conventionally used are well known.

■1 on a part of the outer peripheral surface in the axial direction of a single-layer thick steel pipe of a predetermined length.
411g41a A cable made of wire or steel bar that is tightly wrapped multiple times.

■A short steel sleeve is tightly fitted around a part of the outer peripheral surface in the axial direction of a predetermined length of single-layer G4 pipe.

■ Both pipe ends of a short multi-layer wall thickness 91I pipe, which has a multi-layer wall thickness that does not metallurgically bond the mutual contact surfaces, and has a slit cavity extending in the circumferential direction inside the multi-layer wall thickness. Single-layer thick steel pipes are butted and circumferentially welded together.

By the way, in the case of (1) and (2) above, the cable body is simply wrapped around a part of the outer circumferential surface of a single-layer thick steel pipe manufactured by a conventional method.
Since it can be manufactured by simply fitting a short sleeve made of steel tightly around the outside, it is possible to obtain a long sleeve with no problem in axial strength. Because of the attachments, transportation and handling during on-site construction are cumbersome, and there is also the inconvenience of having to take measures to prevent crevice corrosion between the protruding scraps and the outer circumferential surface of the pipe.

For this reason, recently, the above-mentioned type (2), which does not have such disadvantages, has been attracting attention and being used.

[Problem that the invention seeks to solve]

However, the Club Quarestar steel pipe mentioned above is the third
As shown in the figure, the manufacturing process is relatively narrow (usually 50 mm).
0 to 1,500 m ), slit holes are formed in the intermediate region in the longitudinal direction of a steel plate M having a predetermined length and thickness of 0 to 1,500 m, and are inclined in opposite directions with respect to the longitudinal direction at intervals of circumferential length according to the pipe diameter to be formed. Drill the required number of S, and process the slit holes g14
Roll the temporary material and weld the ends w, w to form the required multi-layer (usually 5 to 7 layers) thick short cylinder (P, ),
The short cylindrical body (r', ) is heated and finished rolled to a predetermined outer diameter and wall thickness using a rear vertical two-roll rolling mill, and then subjected to the required heat treatment and tube expansion processing to form a short multi-layered body. Thick 4A pipe (r
', ) is obtained, and a predetermined length of single-layer thick steel pipes (P, ), (P4) manufactured by a conventional method and having the same outer diameter and wall thickness are butted on both ends of the multi-layer thick steel pipe (P8). It was manufactured by circumferential welding.

Therefore, the slit hole S extends in the circumferential direction in the thick wall of the multi-layer thick steel pipe (Pl), and there is a cross-sectional defect, which has the disadvantage of poor axial strength (tensile strength - bending strength). In addition to that, its single layer wall y′y, steel pipe (P, )
There is also concern about the strength of the butt circumferential weld of , (P, ). In addition, the manufacturing process is complicated and the manufacturing cost is high, making it uneconomical. In addition, the hot finish rolling is performed using a vertical two-roll mill, which imposes restrictions on manufacturing dimensions (particularly length). There was a problem.

In view of these circumstances, the present applicant not only does not have any protruding appendages on the outer circumferential surface of the pipe, but also does not have any slots in the thick wall that would cause cross-sectional defects (and that the axial strength of the pipe should be As a new Love Quarrester m-tube without any problems, a short steel sleeve is installed inside the thick wall of a single-layer fJ4 pipe in a tight crimped state without being metallurgically bonded to the steel pipe base material. A separate application (Patent Application No. 1983) was filed.

An object of the present invention is to provide a manufacturing method that can manufacture the novel rack arrester steel pipe according to the above-mentioned separate application with high efficiency without being subject to any dimensional restrictions.

[Means for solving problems]

In order to achieve the above-mentioned object, the manufacturing method according to the present invention includes forming a hole penetrating in the width direction in a part of the thickness intermediate part in the longitudinal direction,
By hot-rolling the slab with the steel material inserted into the drilled hole, a steel plate is obtained in which the steel material inserted into the drilled hole is pseudo-compressed to the slab base material, and the steel plate is bent in the width direction and formed into a pipe. The feature is that the butt edges on both sides are vertically seamed welded together.

Hereinafter, the manufacturing method according to the present invention will be explained in detail based on FIG.

FIG. 1 shows the manufacturing process according to the present invention, which consists of a slab assembly process (a), a hot rolling process (b), and a pipe manufacturing process (c).

In the slab assembly process (a), a part of the thickness of the slab (1) in the longitudinal direction of the prepared required dimension-material is machined using appropriate means such as machining in a direction perpendicular to the longitudinal direction, in other words, the width One or more stages (one stage in the illustrated example) of holes (2) penetrating in the direction are formed. Next, in the drilled hole (2), a slab made of the same or different material as the slab (1) and whose surface has been previously cleaned mechanically or by pickling, has an outer dimension slightly smaller than the inner dimension of the drilled hole. Insert the steel pieces (3) from both sides of the slab so that they are slightly retracted, and then seal-weld (4) the opening end faces of the slab to complete the assembly. In addition, the seal welding around the opening is performed using steel pieces (
3) is carried out to prevent the material from falling out of the drilled hole and to prevent excessive oxidation between both surfaces due to heating. This step may be omitted if the steel piece (3) is tightly inserted into the hole (2). Further, the number of insertion stages and the size of the steel pieces (3) are determined as appropriate depending on the arrester performance required when the final crack arrester steel pipe is manufactured. Furthermore, the number of steel slabs (3) installed in the longitudinal direction of the slab is determined as appropriate depending on the number of thick steel plates assembled by hot rolling in the next process, the number of assembled hot rolled steel plates, or the coil diameter (length). .

In the hot rolling process (b), the slab assembled in the slab assembly process (a) is heated to a predetermined temperature twice, and then subjected to a reversible or continuous plate mill or hot strip mill to form the inserted steel slab. (3) is in a crimped state in which it is not metallurgically bonded to the slab base material 0), in other words, in a quasi-pressed state, it is flattened in the length direction and installed inside the wall thickness. It is considered to be a thick steel plate with a certain radius, wall thickness, length and diameter), a hot rolled steel plate, or a steel plate as a material for coils, etc.).

In this hot rolling step, it goes without saying that necessary refinement treatments such as heat treatment and surface cleaning of the ingredients are performed either inside or outside the mill line.

In the pipe making process (c), when using the thick steel plate obtained in the hot rolling process (b), a well-known method for making the pipe is used.
I II U OE method, continuous roll forming method, Bendy/Groll method, etc.
When hot-rolled steel sheets or coils are used, electric resistance welding (electric resistance welding) is used as the pipe manufacturing method, so that the quasi-crimped rolling Ji1 station (3') of the inserted steel piece (3) is in the longitudinal direction of the pipe axis. In other words, the resulting thickness f! After bending a four-plate or hot-rolled steel plate or coil in the width direction and forming it into a tube with opposing edges, weld the opposing edges together by submerged arc welding in the former case, or by submerged arc welding in the latter case. A crack arrester steel pipe (6) is vertically seam welded by butt welding and has an annular body (3°) that serves as an arrester that is pseudo-crimped to the base metal installed inside a part of the wall in the axial direction. In addition, an annular body (3") installed inside the thick wall as an arrester in the pipe manufacturing process with
It is preferable that the ring be provided in a pseudo-pressure state with the base metal over its entire circumferential direction, and in order to obtain such an annular body (3"), the vertical seam welding of the chain portion may be carried out, for example, as follows. In other words, the inserted steel piece (3) to form an annular body (3°°) has a groove shape as shown in Fig. 2.
The base metal part is formed into a shape with a narrower notch than the remaining part so that the pseudo-crimped rolled layer III (3') protrudes from the side surface of the base material, and both ends of the pseudo-pressed rolled layer (3') are Welded and joined the
After applying a suitable spacing agent (1) to both surfaces, the base materials may be welded together.

However, when considering the strength distribution in the circumferential direction of longitudinal seam welded steel pipes, due to recent improvements in welding technology, the strength of the longitudinal seam weld is stronger than the strength of the remaining part, so this unstable Considering the fact that crack propagation due to ductile fracture rarely occurs along the weld, the annular body (3') formed inside the thick wall is located at the longitudinal seam weld. It may also be metallurgically joined to the steel pipe base material at the same time, and in such a case, it becomes possible to carry out vertical seam welding under the same conditions as the rest of the seam, improving pipe manufacturing efficiency. . Further, even when the annular body (3'') is installed internally in multiple layers, vertical seam welding can be performed without the same problem.

The above explanation is based on the assumption that the base material fJ4 pipe has a single wall thickness, but when the base material steel pipe is a so-called clad steel pipe with a multilayer wall thickness in which a composite material is metallurgically bonded to the base material. It goes without saying that the present invention can be similarly applied to (in this case, the inserted steel piece forming the annular body (3° (2) It is sufficient to assemble and use a club toss slab in which holes (see Fig. 1) are drilled and steel pieces are inserted.

〔Example〕

Made of steel equivalent to AP l-X65, thickness 235 m,
Prepare a slab with a width of 2260 am and a length of 2000 am,
At the center of the length direction and at the two positions of - and treasure in the thickness direction, two holes of 60 mm diameter were drilled that penetrated in the width direction, and the same steel as above was inserted into the drilled holes. After inserting a pickled and descaled 59 mm diameter steel piece so that it was almost flush, the slab was assembled with the front edges on both sides in contact with the seal f1. After heating the slab to about 1000°C, it was subjected to a reversible plate mill. Hot rolled, thickness 19mm, width 4500cm, length 12000m
US and the thickness of the inserted steel piece is about 9 mm in total of two layers,
A thick steel plate with a length of about 400 axes and a pseudo-rolled layer was obtained, and M
The flJ plate was bent into a tubular shape with an outer diameter of 1400 am using the UOE method, and the opposing edges were joined by vertical seam welding using the submerged arc welding method under the same conditions, and the base metal was welded in the circumferential direction inside the wall thickness. The crack arrester steel pipe is equipped with an annular arrester that is metallurgically bonded to the crack arrester. The axial strength of this crack arrester steel pipe is defined as the axial strength of a conventional crack arrester steel pipe in which a multilayer thick steel pipe is butted against both ends of a short multilayer thick steel pipe with a slit cavity inside the wall thickness and joined by circumferential welding. 1st in comparison
Shown in the table.

Note that Table 1 shows a comparison of the manufacturing costs based on the method of the present invention as 1oo. In addition, the dimensions of the conventional multi-layered crack arrester steel pipe are the same as the outer diameter and wall thickness of the product of the present invention, the length is 500 mm, and the number of layers is 5, with an interval of 2.3.4 mm between each layer. 1 of slit cavities are formed.

Table 1 Note that the tensile strength is determined for the length of 50 mm, which has an annular body (2) of 7 stars in the center in the axial direction, as shown in Figure 4.
When a tensile test was performed by circumferentially welding 7 flanges (F) to both ends of a sample tube (PT, ) of the original size of 00 ■, and fastening pin tabs (T) to these flanges (F) with bolts (13). The tensile strength and bending strength are determined by supporting a full-sized test tube (PT) at two points with a span of 12,000 mm so that the annular arrester ■, etc. is located in the center, as shown in Figure 5. On the other hand, a gate-shaped α loading jig (G
) are placed facing each other in the center between the two support points, and the gate IK!
Yield when subjected to a four-point bending test method (this four-point bending test method is equivalent to a three-point bending test method with a span of 10,000 days) in which a load (Pw) is applied to the center of the cultivated material (G) The respective loads are shown.

As is clear from the results in Table 1, the manufacturing method of the present invention not only reduces the manufacturing cost to about - compared to the conventional method, but also produces products with significantly superior axial strength. It can be seen that the following can be obtained.

〔Effect of the invention〕

As detailed above, according to the manufacturing method of the present invention, crack arrester steel pipes that do not have any appendages protruding from the outer peripheral surface of the pipe and have no problems with axial strength can be manufactured with high efficiency and low cost. Not only can the product be supplied at a low cost, but it also has the great effect of improving the efficiency of pipeline facility operations.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing the manufacturing process of the present invention, FIG. 2 is an enlarged partial cross-sectional view showing an example of vertical seam welding of an annular body installed inside the thick wall in the manufacturing method of the present invention, and FIG. Figure 3 is a schematic diagram showing the manufacturing process of conventional crack arrester steel pipes, Figure 4 is an explanatory diagram of the tensile test method, and Figure 5 is an explanatory diagram of the bending test method. (b) is the homeland indicated by the line A-A in the same figure (a). 1... Slag 2... Hole 3... Steel piece 4... Seal welding 5...
Steel plate 3'...Pseudo-pressed rolled layer 3''...Annular body

Claims (1)

[Claims] A hole penetrating in the width direction is drilled in a part of the middle part of the wall thickness in the longitudinal direction, and a steel material is inserted into the drilled hole.The slab is hot-rolled, and the steel material inserted into the drilled hole becomes the slab motherboard. 1. A method for producing a crack arrester steel pipe, which comprises forming a steel plate into a quasi-crimped steel plate, bending the steel plate in the width direction to form a tubular shape, and vertical seam welding both edges of the steel plate.