Influence of billet cutting length on production cost of 20# cold drawn seamless steel pipe

In the production of cold drawn seamless steel pipe, the cost of pipe blank accounts for 80 ~ 85% of the production cost. Reducing metal consumption, especially reducing the tangible consumption of head and tail cutting in the process of steel pipe production and the intangible consumption of acid pickling after steel pipe annealing, can significantly reduce the production cost and improve the economic benefits of enterprises. Production practice and scientific research show that long and short billets not only consume a lot of metal, but also affect the changes of steel pipe intermediate cutting times and cold wall intermediate processes, so as to affect the times of annealing and pickling lubrication. For a long time, the cutting length of pipe blank is determined by experience, which is difficult to be scientific and standardized.

20210820014746 20289 - Influence of billet cutting length on production cost of 20# cold drawn seamless steel pipe

Table.1 Billet length and production cost

Group

Tube blank length (mm)

Production cost (yuan)

Group

Tube blank length (mm)

Production cost (yuan)

A

590

4749.65

C

930

4821.79

A

630

4659.98

D

970

5035.36

A

660

4621.48

D

1010

4984.04

A

700

4565.58

D

1050

4929.63

A

730

4582.65

E

1090

4995.98

B

770

4533.85

E

1130

4980.46

B

810

4509.52

E

1170

4910.12

B

850

4451.25

F

1210

5033.77

C

890

4895.93

F

1250

4933.04

Table.2 Effect of billet length on intermediate process

Pass times

Outer diameter

Wall thickness

A group:590~700mm

B group:730~850mm

C group:890~930mm

(mm)

(mm)

Hammer head

Cut off

Pickling

Hammer head

Cut off

Pickling

Hammer head

Cut off

Pickling

0

76.0

4.00

Hammer head

Pickling

Hammer head

Pickling

Hammer head

Pickling

1

66.0

3.50

2

58.0

3.00

Pickling

Pickling

Pickling

3

52.0

2.64

Hammer head

Cut off

Pickling

4

42.0

2.75

Hammer head

Pickling

Hammer head

Cut off

Pickling

5

33.0

2.85

Hammer head

Cut off

Pickling

Hammer head

Cut off

Pickling

6

26.0

2.93

Hammer head

Hammer head

Pickling

Hammer head

Pickling

7

20.0

3.00

Cut off

Cut off

Cut off

Average production cost

4649.17 Yuan/ton

4519.32 Yuan/ton

4859 Yuan/ton

Table.3 Effect of billet length on intermediate process

Pass times

Outer diameter

Wall thickness

D group:970~1050mm

E group:1090~1170mm

F group:1210~1250mm

(mm)

(mm)

Hammer head

Cut off

Pickling

Hammer head

Cut off

Pickling

Hammer head

Cut off

Pickling

0

76.0

4.00

Hammer head

Pickling

Hammer head

Pickling

Hammer head

Pickling

1

66.0

3.50

2

58.0

3.00

Pickling

Hammer head

Cut off

Pickling

Hammer head

Cut off

Pickling

3

52.0

2.64

Hammer head

Cut off

Pickling

4

42.0

2.75

Pickling

Pickling

5

33.0

2.85

Hammer head

Pickling

Hammer head

Pickling

Hammer head

Cut off

Pickling

6

26.0

2.93

Hammer head

Cut off

Pickling

Hammer head

Cut off

Pickling

Hammer head

Pickling

7

20.0

3.00

Cut off

Cut off

Cut off

Average production cost

4983 Yuan/ton

4962 Yuan/ton

4983 Yuan/ton

As can be seen from table 1 ~ 3:

  • 1) In the same group, the production cost decreases with the increase of tube blank length;
  • 2) When other conditions are the same, the times of hammer head (including modified head), cutting, annealing and pickling increase, and the production cost increases;
  • 3) The order of hammer head (including changing head), cutting, annealing and pickling moves to the front pass, which increases the production cost;
  • 4) When producing 20# steel tubes of 20×3mm and the billet length varies from 590 to 1250mm, the lowest production cost of the billet cutting length is about 850mm. The difference between the highest and lowest cost is 584.11 yuan/ton.

When other conditions are the same, the longer the billet length is, the longer the steel pipe length of the product pass is, the less the feeding quantity of steel pipe per ton of product is, the less the number of head and tail cutting is, and the metal yield is improved. Therefore, the production cost is reduced.
The number of head changing hammers and cutting times are reduced, the physical consumption of head cutting and tail cutting is reduced, and the production cost is reduced; The times of pickling lubrication and annealing are reduced, the gas consumption, acid consumption and lubricant consumption are reduced, and the production cost is also reduced.
The order of changing the hammer head and cutting is moved forward, the unit weight of the pipe head increases, the physical consumption of metal increases, and the production cost increases. Because the annealing time of large-diameter thick wall pipe is longer than that of small-diameter thin pipe and the iron oxide scale is thicker, the pickling lubrication and annealing sequence move forward, which not only increases the gas consumption per ton of steel pipe, but also increases the intangible consumption during pickling, both of which increase its production cost.

Source: China Seamless Steel Pipe Manufacturer – Yaang Pipe Industry Co., Limited (www.steeljrv.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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