SU1409387A1 - Method of producing multilayer shells with concentric position of turns - Google Patents

Abstract

The invention relates to the manufacture of multilayer pipes of high pressure and m. Used in oil and chemical industries. Pel-improvement of the quality of the longitudinal seams of the shells. In the manufacture of multilayer shells from her, 1 y, y (t) sheets 1, 1, 3, 4, 3, after winding the layers, technical techniques 1K) L01 practical tacks 5 are drawn on both sides (n each edge joint. The distance between technological tacks establish dependencies on the required size of the gap for quality welding of polymers P1NOV and the degree of shell extrusion and on welding of longitudinal welds to ensure the required gap between |; (- the edges of the sheets reduce welding defects, 1 HIBOB. 5 Il. § (About

Description

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The invention relates to the manufacture of multilayer high pressure pipes and can be used in all areas of national economy, mainly in the oil and gas and chemical industries.

The purpose of the invention is to improve the quality of the longitudinal seams of the shells by providing the required clearance in each joint between the transverse edges of the sheets forming the turns of the product.

FIG. 1 shows a package of sheets for a shell having four turns; in fig. 2 and FIG. 3 - a fragment of the end face of a multi-layer shell with a junction of edges in the outer and inner turns, respectively, before the shell is expanded; in fig. 4 and FIG. 5 - fragments of the end of a multi-layer shell with a junction of edges in the outer and inner turns, respectively, after expansion of the shell.

The essence of the proposed method lies in the fact that after folding along its longitudinal axis, a package consisting of overlapped individual sheets 1-4. the number of which is equal to the number of turns produced by my shell, and the length is equal to the circumference of the corresponding turn, before unwrapping the shell at both its ends in each turn, measure the gap So in the resulting junction between the transverse edges of the sheet and set the tacks 5 on both sides of the shell from the specified joint. The distance 1o between the tacks in each case is assumed to be equal to the difference between the required 5 "and the measured So value of the gaps divided by the amount of extension of the shell equal to d.

After expansion, longitudinal seams are welded, the number of which is equal to the number of turns of the shell, ensuring the connection of the edges in the formed edge joints. Depending on the position of the turn relative to the wall, the longitudinal seams are made from the inside or outside of the shell.

The required gap in the junction between the transverse edges of the sheet is chosen such as to ensure optimal welding conditions. For example, in one-arc submerged-arc welding at moderate conditions and a sheet thickness of 5 mm, in order to obtain the required shape of the seam reinforcement and reducing the risk of the formation of defects, in particular the non-fusion of edges, the gap (edge) between the edges of the sheet in the first (extreme) coil should be limited to 5-6 mm, and in the second (intermediate) coil adjacent to it - within 3-4 mm. For two-arc submerged arc welding, the gap SH between the edges of the sheet in the first turn should be increased to 6-8 m. M, and in the second turn to 4-5 mm.

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At values of the gap SH, larger than the specified value, non-fusion is formed in the longitudinal seams, and at smaller gaps the height of the seams exceeds the allowable values.

Providing the required joint clearance

between the transverse edges of the sheets in each turn using the proposed method is achieved by performing shells 5 on both ends of the shells before they are expanded, connecting adjacent turns to a strictly fixed distance between them. The dimensions of the sheets with the proposed method is chosen such that after winding to provide a deliberately smaller gap compared to the required. Due to the subsequent expansion of the shells, the distance between two technological tacks 5, located on either side of each edge joint, increases by U, equal to the product of this distance and degree of expansion, and, accordingly, by the same amount, the gap in the joint between sheet edges. As a result, said gap reaches a predetermined value of SH 5. Technological tacks according to the proposed method are installed at the location of the joints of the edges of the sheets on both ends of the shells, which allows to obtain the same gap for one joint

0 edges along the entire length of the shell.

Thus, the proposed method (unlike the known ones), using the continuous high-performance winding process, allows to produce shells with a concentric arrangement of turns,

5 with sufficient structural strength due to the joining of the edges of the sheets formed in each turn by longitudinal seams, the required quality of which is achieved by providing the required gap between the joined edges of the sheets.

The proposed method (unlike the known ones) is applicable for shells of various diameters and purposes. The preferred option is to manufacture shells

5 with a wall thickness of up to 40 mm, which ensures the necessary conditions for welding the edge joint of intermediate coils using currently known welding methods.

Example. It is necessary to make the shells of the following sizes: internal diameter dew is 1380 mm, the number of turns is 4, the thickness of one turn is S 5.4 mm. In order to ensure minimum interlayer gaps, the shells were expanded by 1%. For longitudinal welds, two-arc welding was used in separate baths with a combined arc protection (the first arc burns in COj, the second - under the flux). Two

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The seam connecting the edges of the sheets in the outer and adjacent intermediate coils were welded from the outer side of the shell, and the two seams connecting the edges of the sheets in the other coils were welded on the inner side of the shell. For the welding process used, based on the amount of metal being deposited and the need to avoid the formation of non-fusion edges, the distance between the edges of the sheets in the outer and inner turns was assumed to be 7 mm, and in intermediate turns 4 mm.

The inner diameter d of the shell after winding, taking into account the specified amount of expansion (1%), was 1367 mm.

The dimensions of the sheets in the package were determined from the perimeter of the turns of the shell after winding:

li Ji (do + S) 4311 mm; L, 5 (de + 3 (mm; 1 f () 4379 mm; 1 5 ((do -r7c5) 4413 mm, where li, Ij, 1z and is the length of the sheets for the inner, two intermediate and outer turns, respectively.

The bag was assembled so that the front edge of each sheet was displaced from the leading edge of the underlying sheet by a distance of approximately 2.3-2.5 m. The sheets in the bag were joined along their longitudinal ends using small tacks, which were done.h manual or semi-automatic arc welding.

After winding, the gap in the junction between the transverse edges in the inner and first intermediate m coils is 1 m.m, in the second intermediate coil - 2 mm, in the outer coil - 3 mm. In order to powering it, it was assumed that the size of the gap in the junction of each turn, measured on both ends of the shells, has the same values.

Mitts, connecting adjacent turns, were set at a distance of 1, between them, equal to

for internal coil mm;

for the first intermediate coil U.1.1. 300mm;

for the second intermediate coil

for outer coil I 00 mm.

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Due to expansion, the distance between tacks increased for the inner coil by 600x0 mm, the first intermediate coil by 300x0.01 3 mm, the second intermediate coil by 200x0 mm, and the outer coil by 400x0 mm. Accordingly, in the indicated turns, the gap in the junction between the transverse edges of the sheet increased at the same angle. As a result, the gap in the junction of the edges of these turns on the expanded shell was 1 + 6 7 mm, mm. 2 + 2 4 mm, 3 + mm respectively, i.e. reached the values specified in the conditions of the problem, which ensured the welding of longitudinal shvov required quality.

The use of the proposed method (in contrast to the known methods) provides cost savings by reducing the consumption of metal and improving the quality of the circumferential seams due to the elimination of loosening of the edges of the inner and outer turns.

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Claims (1)

Invention Formula The method of production of multilayer shells with a concentric arrangement of turns, which includes assembling an overlap of a package of sheets, the number of which is equal to the number of turns of the shell, and the length is equal to the circumference of the corresponding turn, folding the package along its longitudinal axis, connections with technological hooks on the ends of the shell, expansion and welding of the joint formed in each turn between the transverse edges of the sheets, characterized in that, in order to improve the quality of the longitudinal seams by ensuring the required the gap between the transverse edges of the sheets, before expansion, the specified gaps in each turn are measured at the ends of the shells, the technological tacks are set on either side of the gaps, and the distance between the two tacks is equal to I, - And where 5 is the gap required for welding at the joint between the edges; Si, - the measured gap in the junction between edges; D-value expansion. - j .d