According to GOST 28548-90 "welded pipe" is a product made of strips or sheet metal by molding and subsequent welding.
Alloy additives in the steel, increase the strength characteristics of pipes.
GOST 10706-76 applies to steel, electric-welded pipes of General purpose. Product diameter can range from 426 to 1620 mm. the standard establishes requirements for the impact strength of metal, the number of transverse seams, to strengthen internal seam, and to the chamfer on the end product.
Pipe manufactured according to GOST 10706-76, can relate to one of the groups: with standard mechanical properties standard chemical properties, with standard chemical and mechanical properties, and without standardization of the chemical composition and mechanical properties.
According to the standards, the ends of the steel pipes must be cut at a right angle, and on the product surface should be no cracks, delamination, dents and sunsets.
Welded pipes are widely used in the construction of pipelines and steel structures.
And mechanical properties of carbon steel grades ST2, St3 (all degrees of oxidation) according to GOST 380-94, category 1 according to GOST 14637-89;
B — chemical composition of carbon steel grades ST2, St3 (all degrees of oxidation) with the chemical composition according to GOST 380-94 and GOST 14637-89;
The chemical composition and mechanical properties of carbon steel grades ST2 (all degrees of oxidation) according to GOST 380-94, category 2 according to GOST 14637-89, St3kp GOST 380-94, category 2 and 3 according to GOST 14637-89, St3ps, st3sp according to GOST 380-94, categories 2, 3, 4 and 5 according to GOST 14637-89 and low alloy steel, the carbon equivalent which does not exceed 0,48 %;
D — without standardization of mechanical properties and chemical composition, but with standardization of hydraulic test pressure.
Tubes of groups A and b shall withstand mechanical testing of welded joints in tension according to GOST 6996-66. The tensile strength of welded joint shall not be below the interim resistance of the base metal specified for pipes made of this steel grade.
At the request of the consumer pipe group must be able to withstand the test of the toughness of the base metal. Rules of the toughness of the base metal shall be as specified in the table.
Steel grade |
Wall thickness of pipe, mm |
The impact strength KCU, kgf m/cm2 (MJ/m2) at the test temperature, °C |
||
+20 |
-20 |
-40 |
||
minimum |
||||
Ст3пс3, Ст3сп3 |
От 5 до 9 включ. Св. 9 « 25 « « 25 |
6,0 (0,59) 5,0 (0,49) 3,0 (0,29) |
- - - |
- - - |
Ст3пс4, Ст3сп4 |
От 5 до 9 включ. Св. 9 « 25 « « 25 |
- - - |
2,0 (0,2) 1,5 (0,15) - |
- - - |
Low alloy steel |
All the walls |
- |
- |
2,5 (0,24) |
Note. By agreement between manufacturer and consumer impact toughness of the base metal of pipes of low-alloy steel at minus 60 °With should be not less than 2.5 kgf * m/cm2 (0,24 MJ/m2). |
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