After bending 180 degrees with the bending center diameter specified in the table, no cracks should occur on the surface of the bent part of the steel bar.
Trademark |
Nominal diameter a mm |
Bending test Bend center diameter |
HRB335 |
6-25 28-50 |
3a 4a |
HRB400 |
6-25 28-50 |
4a 5a |
HRB500 |
6-25 28-50 |
6a 7a |
2.Reverse bending performance
According to the requirements of the purchaser, the steel bars can be subjected to reverse bending performance test.
The bending center diameter of the reverse bending test is correspondingly increased by one steel bar diameter compared with the bending test. First, bend it forward at 45 degrees, then bend it in the reverse direction at 23 degrees, and then bend it in the reverse direction at 23 degrees. After the reverse bending test, no cracks shall occur on the surface of the bending part of the steel bar.
3.Surface quality
The surface of the steel bars is allowed to be free of cracks, scars and folds.
Bumps are allowed on the surface of the steel bars, but they shall not exceed the height of the transverse ribs. The depth and height of other defects on the surface of the steel bars shall not be greater than the allowable deviation of the size of the location.
4. Dimensions, appearance, weight and allowable deviations
1) Nominal diameter range and recommended diameter
The nominal diameter range of steel bars is 6~25mm, and the standard recommended nominal diameters of steel bars are 6, 8, 10, 12, 16, 20, 25, 32, 40, and 50mm.
2) Permissible deviations in surface shape and size of ribbed steel discs
Ribbed steel transverse ribs shall comply with the following basic requirements:
The angle β between the transverse rib and the axis of the steel plate should not be less than 45 degrees. When the angle is not greater than 70 degrees, the directions of the transverse ribs on the opposite sides of the steel bar should be opposite;
The distance l between transverse ribs shall not be greater than 0.7 times the nominal diameter of the steel bar;
The angle α between the side of the transverse rib and the surface of the steel bar shall not be less than 45 degrees;
The sum of the gaps between the ends of the transverse ribs on opposite sides of the steel bar (including the width of the longitudinal ribs) should not be greater than 20% of the nominal circumference of the steel bar;
When the nominal diameter of the steel bar is not greater than 12mm, the relative rib area should not be less than 0.055; when the nominal diameter is 14mm and 16mm, the relative rib area should not be less than 0.060; when the nominal diameter is greater than 16mm, the relative rib area should not be less than 0.065.
3) Length and allowable deviation
a. Length: Steel bars are usually delivered in fixed lengths, and the specific delivery length should be specified in the contract; when steel bars are delivered in coils, each coil should be one steel bar, and each batch is allowed to have 5% of the number of coils (less than There can be two plates when there are two plates) composed of two steel bars. The disc weight and disc diameter are determined by negotiation between the supply and demand parties.
b. Allowable length deviation: The allowable length deviation of steel bars when delivered to fixed length shall not be greater than +50mm.
c. Curvature and ends: The bending strain of straight steel bars does not affect normal use, and the total curvature is not greater than 40% of the total length of steel bars; the ends of steel bars should be sheared straight, and local deformation should not affect use.
Standard Classification of SSAW Steel Pipes
The spiral seam submerged arc welded steel pipe SY5036-83 for pressure-bearing fluid transportation is mainly used for pipelines transporting oil and natural gas; the spiral seam high-frequency welded steel pipe SY5038-83 for pressure-bearing fluid transportation is welded by high-frequency lap welding. Spiral seam high-frequency welded steel pipes are used for transporting pressure-bearing fluids. The steel pipes have strong pressure-bearing capacity, good plasticity, and are easy to weld and process. Generally, spiral seam submerged arc welded steel pipes SY5037-2000 are used for low-pressure fluid transport, using double-sided automatic submerged arc welding. Or submerged arc welded steel pipes made by single-sided welding for general low-pressure fluid transportation such as water, gas, air, and steam.
Commonly used standards for spiral steel pipes are generally divided into: SY/T5037-2000 (industry standard, also called spiral submerged arc welded steel pipe for ordinary fluid transportation pipelines), GB/T9711.1-1997 (national standard, also called oil and gas industry transportation steel pipe The first part of the delivery technical conditions: Grade A steel pipe (the strict requirements include GB/T9711.2 Grade B steel pipe and GB/T9711.3 Grade C steel pipe)), API-5L (American Petroleum Institute standard, also called pipeline steel pipe; among them Divided into two levels: PSL1 and PSL2), SY/T5040-92 (spiral submerged arc welded steel pipe for piles) Spiral submerged arc welded steel pipe for pressure fluid transportation (SY5036-83) is made of hot-rolled steel strip coils Blank, often warm spiral formed, welded by double-sided submerged arc welding, spiral seam steel pipe used for pressure fluid transportation. Steel pipes have strong pressure-bearing capacity and good welding performance. They have undergone various rigorous scientific inspections and tests and are safe and reliable to use. The steel pipe has a large diameter, high transportation efficiency, and can save investment in laying pipelines. Mainly used for pipelines transporting oil and natural gas.