GOST 8732 78. Seamless seamless hot-formed steel pipes. Assortment
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GOST 8732−78 applies to hot seamless steel pipe for General purposes, manufactured from the outside diameter, wall thickness and length.
The length of the pipe must be manufactured:
random lengths — ranging from 4 to 12.5 m;
measuring length within off-gage;
dimensional length within off-gage length with an allowance for each cut to 5 mm;
approximate length within off-gage length.
By agreement with the consumer allowed to manufacture pipes with a length beyond the limits specified for pipes of random length. For pipes with wall thickness more than 16 mm length of the measuring tubes is determined by agreement between manufacturer and consumer. Pipe approximate length produce on demand of the consumer.
Maximum deviations along the length of the pipes lengths and dimensional length should not exceed: +10 mm — with length up to 6 m; +15 mm — at length of over 6 m or with outer diameter more than 152 mm; ±500 mm for an approximate length.
Limit deviations for outer diameter and wall thickness of pipes should not exceed the data given in the following tables
|External diameter, mm||The maximum deviations of tubes for precision manufacturing|
|To 50 inclusive||±0.5 mm||±0.5 mm|
|SV.50 to 219 «||±0,8%||±1,0%|
|External diameter, mm||Wall thickness, mm||Tolerances for wall thickness of tubes precision manufacturing, %|
|To 219||To 15 inclusive||±12,5||+12,5|
|More than 15 to 30||+10,0
|30 and above||±10,0||+10,0|
|More than 219||To 15 inclusive||+12,5|
|More than 15 to 30||±12,5|
|30 and above||+10,0|
By agreement with the consumer pipes can be manufactured with a combination of extreme deviations, such as: the outside diameter of high accuracy according to GOST 9567, and the wall thickness ordinary precision, etc.
Ovality and raznoshennoy pipes should take the size of the pipes for maximum deviations in diameter and wall thickness.
The curvature of any section of the tube per 1 m of length should not exceed: 1.5 mm — for pipes with wall thickness up to 20 mm; 2.0 mm — for pipes with wall thickness more than 20 mm to 30 mm; 4,0 mm — for pipes with wall thickness over 30 mm.
At the request of the consumer pipes shall be supplied by the inner diameter and wall thickness, and inner and outer diameter and raznoshennoy.
Tolerances for inside diameter for pipe diameters 70−203 mm, wall 7−20 mm and a ratio of diameter and wall thickness equal to or less than 10, shall not exceed the respective limit deviations of the outside diameter specified in the above tables.
For other pipe sizes, the maximum deviations at the inner diameter are set by agreement between manufacturer and consumer.
Buy hot-deformed seamless steel tubes supplied according to standards of GOST 8732−78, the company offers Electrocentury-steel. Are economically advantageous prices from manufacturers. The supplier provides timely delivery of products to any place specified by the client.
The hot rolled seamless steel pipes according to GOST 8732−78 are made of steel and technical requirements are regulated by GOST 8731−74.
Depending on the quality parameters of the pipe shall be manufactured of the following groups:
And — with standard mechanical properties of steel grades St2sp, St4sp, St5sp, St6sp;
B — with standard chemical composition of steel;
In — with standard mechanical properties and chemical composition;
G — standard chemical composition and controlled mechanical properties of thermally treated samples. Norms of mechanical properties should correspond to those in standards for steel;
D — without standardization of mechanical properties and chemical composition, but with the standard hydraulic test pressure.
|Steel grade||Rupture strength sin MPa (kgf/mm2)||The yield stress st, MPa (kgf/mm2)||Elongation d5, %|
|not less than|
|St2sp||343 (35)||216 (22)||24|
|St4sp||412 (42)||245 (25)||20|
|St5sp||490 (50)||274 (28)||17|
|St6sp||588 (60)||304 (31)||14|
Note. By agreement between manufacturer and consumer is made of steel pipes маркиСт3сп.
|Steel grade||Rupture strength sin MPa (kgf/mm2)||The yield stress st, MPa (kgf/mm2)||Elongation d5, %||Brinell hardness number (wall thickness more than 10 mm)|
|not less than||Indentation diameter, mm, not less||The number of hardness HB, no more|
|10||353 (36)||216 (22)||24||5,1||137|
|20||412 (42)||245 (25)||21||4,8||156|
|35||510 (52)||294 (30)||17||4,4||187|
|45||588 (60)||323 (33)||14||4,2||207|
|10G2||421 (43)||265 (27)||21||4,3||197|
|40X||657 (67)||-||9||3.7 V||269|
|15KHM||431 (44)||225 (23)||21||-||-|
|30KHMA||588 (60)||392 (40)||13||-||-|
|12KHN2||539 (55)||392 (40)||14||-||-|
|St4sp||412 (42)||245 (25)||20||-||-|
|St5sp||490 (50)||274 (28)||17||-||-|
1. In the manufacture of pipes with wall thickness more than 45 mm the mechanical properties shall be established in consultation with the consumer.
2. Mechanical properties of pipes made from steel grades not listed in the above tables, and the rules of impact strength and relative contraction for steel of all grades are established by agreement between manufacturer and consumer.
At the request of the consumer pipe shall be manufactured heat treated. Heat treatment regime and norms of mechanical properties are set according to normative-technical documentation approved in the established order.
On the surface of the pipe are not allowed cracks, slivers, flaws and sunsets. Allowed some minor nicks, dents, risks, thin layer of oxides, traces of Stripping defects and small slivers, if they do not take wall thickness outside negative deviations.
The pipe ends must be cut at right angle, at the same time allowed the formation of the chamfer at an angle of at least 70° to the axis of the pipe. The pipe ends must be cleaned of burrs; allowed the formation of a chamfer at their removal. It is allowed to trim the ends of tubes with wall thickness of 20 mm or more oxy-fuel, plasma cutting or saw.
When cutting pipes with a torch or plasma cutting the stock to length of the pipes should be at least 20 mm for each cut.
On demand of the consumer is allowed to produce pipe with a wall thickness of 20 mm or more, manufactured from rolled or forged blanks, without cropping the ends. In this uncut part of the pipe marked with paint and the length of the pipe at delivery not included.
At the request of the consumer at the ends of the pipes to be welded, with wall thickness from 5 to 20 mm should be removed chamfer at an angle of 35−40° to the pipe end. This should be left to the socket ring width of 1−3 mm.
To purchase affordable seamless tubes meet the requirements of GOST 8732−78, the company offers Electrocentury-steel. The supplier ensures prompt delivery of hire to any destination specified by the customer.