RU2180691C1 - Pipe for gas and oil product lines and method of its manufacture - Google Patents

Abstract

FIELD: metallurgy, particularly, manufacture of pipes for gas and oil product lines. SUBSTANCE: pipe possesses high process and strength properties, ductility, impact strength at temperatures to minus 100 C, resistance to embrittlement, cracking, corrosion, increased durability and operate reliability. Pipe is manufactured from hot-rolled sheet produced from steel melted from original or pure charge materials with the following amounts of components, wt.%: carbon 0.03-0.11; manganese 0.90-1.80; silicon 0.06-0.60; chromium 0.006-0.30; nickel 0.005-0.30; vanadium 0.02-0.12; niobium 0.03-0.10; titanium 0.010-0.040 aluminum 0.010-0.055; calcium 0.001-0.005; sulfur 0.0005-0.008; phosphorus 0.0005-0.010; nitrogen 0.001-0.012; copper 0.005-0.25; antimony 0.0001-0.005; tin 0.0001-0.007; arsenic 0.0001-0.008; the balance, iron. In this case, content of carbon, nitrogen, copper phosphorus, antimony, tin and arsenic shall satisfies relations: C+10N < 0.14; 10P+Cu < 0.14; 2P+Sn+Sb+As < 0.035, where C, N, P, Cu, Sn, Sb, As are concentration of carbon, nitrogen, phosphorus, copper, tin, antimony and arsenic, wt.%; sheet hot rolling is carried out with reduction degree in each next run reduced by a factor of 1.25-2.5 as compared with that of the previous run. Temperature of rolling shall satisfy the relation in which initial temperature of rolling is lower than finishing temperature of rolling by 200 C. Offered pipe is suitable for operation in aggressive media at temperatures from minus 100 to plus 450 C and under conditions of the Extreme North. Pipes manufactured in compliance with the claimed invention meet all high modern requirements imposed on pipes for gas and oil product lines and kept at the level of the best foreign analogs. EFFECT: high quality product. 2 cl, 4 tbl

Description

The invention relates to the field of metallurgy, in particular, to the production of pipes for oil and gas pipelines and other structures operating under pressure at temperatures from minus 100 to plus 450 ^o C.

Known pipe for oil and gas pipelines made of cold rolled steel containing carbon, manganese, sulfur, nickel, molybdenum, copper, rare-earth metals, magnesium, silicon, phosphorus, chromium, nitrogen, vanadium, cobalt, tungsten, calcium, iron and impurities. The pipe has a high resistance to corrosion in an environment of H ₂ S-CO ₂ -Cl ^- (US patent 4400211, C 22 C 19/05, 08/23/1983).

 Also known is a welded pipe for oil wells with high viscosity at low temperature, made of hot rolled steel containing carbon, manganese, silicon, phosphorus, sulfur, calcium, iron and impurities (Japanese patent JP 51-85932, C 21 D 9/46, 05/28/1982).

 The closest analogue to the present invention is the known pipe for oil and gas pipelines made of hot-rolled steel containing carbon, manganese, silicon, vanadium, niobium, nitrogen, nickel, chromium, aluminum, rare-earth metals, titanium, copper, iron and impurities (SU 863707, C 22 C 38/58, 09/15/1982).

 Known pipes do not have the required modern complex of qualitative characteristics of the technological, mechanical and operational properties of the metal.

 A known method of manufacturing pipes, including steel smelting, hot rolling of ingots per sheet, sheet forming and pipe welding (Matveev Yu.M., Ruzhinsky M. B., Romashov A. A. and Khalomets E. M. "Technology for the production of electric-welded pipes" , M., Metallurgy, 1967, p. 78-130).

 There is also a method of producing high-strength welded pipes for oil pipelines, including the smelting of steel containing 0.08-0.26% carbon, 0.8-1.9% manganese, up to 0.5% silicon, the rest is iron and impurities, casting, hot rolling of ingots, hardening, winding into a roll, molding of a tube stock, welding, hardening and tempering (DE 36117725 Al, C 21 D 8/10, 12/04/1986).

 A known method of manufacturing a steel pipe by electric welding, including the smelting of steel containing carbon, manganese, aluminum, vanadium and niobium, casting, hot rolling of a strip billet, molding and welding (US 4410369, C 21 D 8/10, 10/18/1983).

 The closest analogue of the invention is a known method for the production of pipes for oil pipelines, including the smelting of steel containing carbon, manganese, silicon, nickel, chromium, copper, titanium, calcium, aluminum, nitrogen, sulfur, vanadium and iron, processing in a ladle, casting, hot rolling in several passes on a sheet with a given degree of deformation, molding of a tube stock and welding (RU 2048541 C1, C 21 D 8/02, 11/21/1995).

 Known methods do not allow to produce a pipe that has the high technological, mechanical and operational properties required today for weldability, ductility, strength, impact strength, especially at low temperatures, crack resistance and corrosion resistance.

The technical result of the invention is to obtain a pipe for operation in aggressive environments in the temperature range from minus 100 to plus 450 ^o C, which has high technological characteristics, strength properties, impact strength, resistance to embrittlement, corrosion resistance, increased durability and reliability in operation.

To achieve a technical result, the pipe for oil and gas product pipelines is made of hot-rolled steel sheet, the sheet is obtained from steel smelted on original or pure charge materials in the following ratio of components, wt.%:
Carbon - 0.03-0.11
Manganese - 0.90-1.80
Silicon - 0.06-0.60
Chrome - 0.005-0.30
Nickel - 0.005-0.30
Vanadium - 0.02-0.12
Niobium - 0.03-0.10
Titanium - 0.010-0.040
Aluminum - 0.010-0.055
Calcium - 0.001-0.005
Sulfur - 0.0005-0.008
Phosphorus - 0.0005-0.010
Nitrogen - 0.001-0.012
Copper - 0.005-0.25
Antimony - 0.0001-0.005
Tin - 0.0001-0.007
Arsenic - 0.0001-0.008
Iron - Else
while the contents of carbon, nitrogen, copper, phosphorus, antimony, tin and arsenic must satisfy the ratios
C + 10N <0.14
10P + Cu <0.14
2P + Sn + Sb + As <0.035,
where C, N, P, Cu, Sn, Sb, As are the concentrations of carbon, nitrogen, phosphorus, copper, tin, antimony and arsenic, wt.%.

To achieve a technical result, a method for producing a pipe for oil and gas products involves steel smelting, processing in a ladle, casting, hot rolling in several passes with a given degree of deformation per sheet, molding and welding of the pipe, steel is smelted on original or clean charge materials in the following ratio of components, wt .%:
Carbon - 0.03-0.11
Manganese - 0.90-1.80
Silicon - 0.06-0.60
Chrome - 0.005-0.30
Nickel - 0.005-0.30
Vanadium - 0.02-0.12
Niobium - 0.03-0.10
Titanium - 0.010-0.040
Aluminum - 0.010-0.055
Calcium - 0.001-0.005
Sulfur - 0.0005-0.008
Phosphorus - 0.0005-0.010
Nitrogen - 0.001-0.012
Copper - 0.005-0.25
Antimony - 0.0001-0.005
Tin - 0.0001-0.007
Arsenic - 0.0001-0.008
Iron - Else
while the contents of carbon, nitrogen, copper, phosphorus, antimony, tin and arsenic must satisfy the ratios
C + 10N <0.14
10P + Cu <0.14
2P + Sn + Sb + As <0.035,
where C, N, P, Cu, Sn, Sb, As are the concentrations of carbon, nitrogen, phosphorus, copper, tin, antimony and arsenic, wt.%,
hot rolling is carried out with a decrease in the degree of deformation in each subsequent pass 1.25-2.5 times in comparison with the previous pass and at a temperature satisfying the following ratio:
Tn.pr. - Tk.pr. <200 ^o C
where Tn.pr. and Tk.pr. - the temperature of the beginning and end of rolling in the aisle, respectively.

 The principal distinguishing feature of the proposed technical solution is that the pipe is made of steel smelted on original or pure charge materials with the stated chemical composition and low impurity contents. Strict compliance with the requirements for the pipe and the method of its production is justified by research results.

 So, if the carbon content in the pipe metal is above 0.11%, then the weldability, ductility and toughness of the steel are deteriorated; if the carbon content is below 0.03%, the strength of the steel decreases.

 The increase in the content of manganese, silicon and chromium, respectively, above 1.8; 0.6 and 0.3% reduces toughness and increases the temperature of the brittle-viscous transition. The introduction of these elements in amounts below the declared minimum does not provide the required strength of the metal.

Increasing the content of titanium, niobium and vanadium above the upper limits reduces the ductility and toughness of the base metal and the heat affected zone of the welded joint at low and high temperatures. When the content of these elements is less than the lower limits is not achieved the necessary strength and ductility of steel at temperatures up to plus 450 ^o C.

 The content of phosphorus and sulfur in the steel within the specified limits provides high weldability, cold resistance and corrosion resistance of the metal.

 The positive role of calcium in the selected concentration range is due to its favorable effect on the morphology of sulfides: globulization of sulfides increases the ductility and toughness of steel.

Compliance ratio
C + 10N <0.14
provides high weldability, ductility and toughness of the metal. Exceeding this value leads to a significant decrease in these characteristics of steel.

If the restriction is not met
10P + Cu <0.14
a brittle fracture appears and the resistance to brittle fracture and the corrosion resistance of the metal noticeably decrease.

Non-compliance
2P + Sn + Sb + As <0.035
increases the probability of nucleation and propagation of cracks and leads to embrittlement of the metal during the manufacture and operation of the pipe.

The method of pipe production involves the smelting of steel using primordial or pure charge materials, out-of-furnace treatment in a ladle, rolling on a sheet in two or more passes, and the degree of deformation in each subsequent pass should be 1.25-2.5 times less than in previous at a temperature that satisfies the following ratio:
Tn.pr. -Tk.pr. <200 ^o C
where Tn.pr. and Tk.pr. - the temperature of the beginning and end of rolling in the aisle, respectively.

 If during rolling the sheet, the degree of deformation in each subsequent pass will differ from the previous one by more than 2.5 times, then banding will appear in the fracture of the metal, and the ductility of the steel will be lower than the required value; and if the difference in the degrees of deformation is less than 1.25 times, then the fracture of the metal becomes larger and the toughness of the steel decreases.

If the temperature difference between the beginning and end of rolling in the passage exceeds 200 ^o C, the metal structure will be enlarged and the impact strength of steel will decrease.

 Examples of the implementation of the claimed method of manufacturing a pipe are shown in table 1-4.

 In the table. 1 shows the technological features of steel smelting and thermal deformation modes of sheet rolling for pipes. Swimming trunks 1, 2 and 3 were carried out in open furnaces on original or pure charge materials with out-of-furnace refining in the ladle. Smelting 4 for comparison is melted on a conventional charge material - steel scrap without secondary furnace refining.

 Table 2 shows the chemical composition of the pipe metal.

 Table 3 shows the influence of the characteristic ratios of the carbon content and harmful impurities on the brittle viscosity properties of the pipe metal.

 Table 4 shows the mechanical properties of the pipe metal.

 The above results indicate that the claimed chemical composition and technological parameters of the method of manufacturing the pipe ensure the achievement of high modern requirements for technological, mechanical and operational characteristics of the pipe. Pipes surpass well-known domestic ones and are at the level of the best foreign analogues.

Claims (2)

1. The pipe for oil and gas pipelines, made of hot-rolled steel sheet, characterized in that the sheet is obtained from steel smelted on original or pure charge materials in the following ratio of components, wt. %:
Carbon - 0.03-0.11
Manganese - 0.90-1.80
Silicon - 0.06-0.60
Chrome - 0.005-0.30
Nickel - 0.005-0.30
Vanadium - 0.02-0.12
Niobium - 0.03-0.10
Titanium - 0.010-0.040
Aluminum - 0.010-0.055
Calcium - 0.001-0.005
Sulfur - 0.0005-0.008
Phosphorus - 0.0005-0.010
Nitrogen - 0.001-0.012
Copper - 0.005-0.25
Antimony - 0.0001-0.005
Tin - 0.0001-0.007
Arsenic - 0.0001-0.008
Iron - Else
while the contents of carbon, nitrogen, copper, phosphorus, antimony, tin and arsenic must satisfy the ratios
C + 10N <0.14
10P + Cu <0.14
2P + Sn + Sb + As <0.035,
where C, N, P, Cu, Sn, Sb, As are the concentrations of carbon, nitrogen, phosphorus, copper, tin, antimony and arsenic, wt. % 2. A method of manufacturing pipes for oil and gas products pipelines, including steel smelting, processing in a ladle, casting, hot rolling on a sheet in several passes with a given degree of deformation, molding and welding, characterized in that the steel is smelted on original or pure charge materials in the following ratio of components wt. %:
Carbon - 0.03-0.11
Manganese - 0.90-1.80
Silicon - 0.06-0.60
Chrome - 0.005-0.30
Nickel - 0.005-0.30
Vanadium - 0.02-0.12
Niobium - 0.03-0.10
Titanium - 0.010-0.040
Aluminum - 0.010-0.055
Calcium - 0.001-0.005
Sulfur - 0.0005-0.008
Phosphorus - 0.0005-0.010
Nitrogen - 0.001-0.012
Copper - 0.005-0.25
Antimony - 0.0001-0.005
Tin - 0.0001-0.007
Arsenic - 0.0001-0.008
Iron - Else
while the contents of carbon, nitrogen, copper, phosphorus, antimony, tin and arsenic must satisfy the ratios
C + 10N <0.14
10P + Cu <0.14
2P + Sn + Sb + As <0.035,
where C, N, P, Cu, Sn, Sb, As are the concentrations of carbon, nitrogen, phosphorus, copper, tin, antimony and arsenic, wt. %
hot rolling is carried out with a decrease in the degree of deformation in each subsequent pass 1.25-2.5 times in relation to the previous pass and at a temperature satisfying the following ratio:
T n pr. - T K. pr. <200 ^o C,
where T n etc. and T K., etc. - the temperature of the beginning and end of rolling in the aisle, respectively.

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