RU2227762C1 - Method for making helical-seam tubes of rolled sheets - Google Patents

Abstract

FIELD: metallurgy, namely manufacture of helical-seam tubes for gas and oil pipelines. SUBSTANCE: method for making helical-seam tubes of rolled sheets comprises steps of butt welding of sheets to strip; shaping tube; welding it by helical seam; cutting welded tubular blank by measured-length tubes; finishing them; using for tube making steel composition at next relation of ingredients, mass%: carbon, 0.03 - 0.15; silicon, 0.1 -0.7; manganese, 0.6 - 2.0; vanadium, 0.01 - 0.15; niobium, 0.01 - 0.12; chrome, 0.01 - 0.3; nickel, 0.01 -0.6; copper, 0.01 - 0.6; aluminum, 0.01 - 0.1; titanium, 0.01 - 0.1; calcium, 0.0005 - 0.02; nitrogen, 0.003 - 0.012; sulfur, 0.001 - 0.01; phosphorus, 0.001 - 0.02; iron, the balance; welding sheets to strip only by inner butt joint while using sheets whose length is normalized with use of mathematical relation; cutting blank by measured-length tubes including portion of shell containing butt joint. Steel may contain in addition molybdenum in quantity 0.01 - - 0.5 mass%. EFFECT: lowered number of flaws of butt welded seam, especially in zone of tube helical seam. 2 cl, 1 ex

Description

The invention relates to metallurgy, and more particularly to the production of spiral seam pipes for gas and oil pipelines.

A known method for the production of spiral-seam pipes from sheet metal (analogue), including welding sheets into a strip using butt welding, forming a pipe, welding a spiral seam, cutting pipes to measured lengths and finishing finished pipes (US patent No. 3383488, class 219- 62, 1968).

There is also a method of manufacturing spiral-seam pipes from sheet metal (prototype), which includes welding sheets into a butt strip, forming a pipe, welding a spiral seam, cutting pipes to measured lengths and finishing finished pipes, while welding the sheets end-to-end on the inner and outer surfaces sheets (USSR AS No. 806195, class B 21 C 37/12, 1979).

The main disadvantages of the known methods for the production of spiral-seam pipes (analogue and prototype) are the unsatisfactory quality, low reliability of the pipes due to the presence of defects in the butt joints, especially at the joints of the butt and spiral joints.

The technical result of the invention is to eliminate the above disadvantages and to improve the quality, reliability and durability of the resulting pipes.

The technical result is achieved by the fact that in the method for the production of spiral seam pipes from sheet metal, including welding sheets with a butt seam into a strip, pipe forming, welding a spiral seam, cutting the pipe into measured lengths and finish, according to the invention, the pipe is made of steel of the following chemical composition at ratio of ingredients, wt.%:

Carbon 0.03-0.15

Silicon 0.1-0.7

Manganese 0.6-2.0

Vanadium 0.01-0.15

Niobium 0.01-0.12

Chrome 0.01-0.3

Nickel 0.01-0.6

Copper 0.01-0.6

Aluminum 0.01-0.1

Titanium 0.01-0.1

Calcium 0.0005-0.02

Nitrogen 0.003-0.012

Sulfur 0.001-0.01

Phosphorus 0.001-0.02

Iron Else

while welding the strip is made from sheets of length determined by the formula

where Ll is the length of the sheet;

Lmp is the required pipe length;

in - the width of sheet metal;

α is the angle of molding

welding of sheets into a strip is carried out only by an internal joint, and when cutting a pipe into measured lengths, a shell containing a joint is cut.

In addition, the steel may additionally contain molybdenum in an amount of 0.01-0.5 wt.%.

A specific example of a method for the production of spiral suture pipes.

For the production of spiral-seam pipes with a diameter of 1420 mm and a wall thickness of 18.7 mm at the “2520” VTZ mill, steel of the following chemical composition is used with a ratio of ingredients, wt.%: Carbon 0.06; silicon 0.4; 1.5 manganese; vanadium 0.083; niobium 0.06; chrome 0.15; nickel 0.15; copper 0.15; aluminum 0.05; titanium 0.05; calcium 0.01; nitrogen 0.007; sulfur 0.005; phosphorus 0.01; iron is steel, while steel may additionally contain 0.2 molybdenum. The strip from which the pipe is molded is welded only with an internal joint, and the length of the sheets to be welded is determined by the formula

where Lmp is the given pipe length equal to 11.5 m;

B - sheet metal width equal to 2.484 m;

α is the molding angle,

where Dav is the average diameter of the pipe;

Dav = Dn-δ;

Dn - the outer diameter of the pipe;

δ is the wall thickness of the pipe,

Dn = 1.42m;

α = 0.599523 rad .;

Sinα = 0.5642;

Cosα = 0.825605,

The length of the sheet (sheet metal) is 24 m. After the process of forming the pipe from the strip, a spiral seam is welded and the pipe is cut into measured lengths of 11.5 m, while a 2.05 m wide casing containing the butt weld is cut from the pipe billet. After cutting the pipes to measured lengths, the pipes are finally finished with subsequent storage.

Using this method can improve the quality, reliability and durability of the obtained spiral-seam pipes by 15%.

Claims (2)

1. Method for the production of spiral seam pipes from sheet metal, including welding sheets with a butt weld into a strip, forming a pipe, welding a spiral seam, cutting pipes to measured lengths and finishes, characterized in that the pipes are made of steel of the following chemical composition with a ratio of ingredients, wt. %: Carbon 0.03-0.15 Silicon 0.1-0.7 Manganese 0.6-2.0 Vanadium 0.01-0.15 Niobium 0.01-0.12 Chrome 0.01-0.3 Nickel 0.01-0.6 Copper 0.01-0.6 Aluminum 0.01-0.1 Titanium 0.01-0.1 Calcium 0.0005-0.02 Nitrogen 0.003-0.012 Sulfur 0.001-0.01 Phosphorus 0.001-0.02 Iron Else while welding the strip is made from sheets of length determined by the formula:

where L _l - the length of the sheet; L _Tr - the required length of the pipe; In - the width of sheet metal; α is the molding angle; and carry it out only with an internal connecting seam, and when cutting the pipe into measured lengths, a shell containing the connecting seam is cut off. 2. The method according to claim 1, characterized in that the steel further comprises molybdenum in an amount of 0.01-0.5 wt.%.