Material and technological properties of spiral submerged arc welded pipe

Material and technological properties of spiral submerged arc welded pipe

Raw material

Q235A, Q235B. Q23b, 0Cr13, 1Cr17, 00Cr19Ni11, 1Cr18Ni9, 0Cr18Ni11Nb. Q345 L245 L290 X42 X46 X70 X80

Process performance

Flexural properties

After bending 180 degrees according to the diameter of the bending center specified in the table below, no cracks may occur on the surface of the bending part of the reinforcing bar.

Brand name

Nominal diameter a

Mm

Bending test

Bending center diameter

HRB335

6-25

28-50

3A

4A

HRB400

6-25

28-50

4A

5A

HRB500

6-25

28-50

6A

7A

Reverse Bending Performance

According to the requirement of the demand side, the steel bar can be tested for the reverse bending property of the spiral submerged arc welded pipe.

The bending center diameter of the reverse bending test is one more steel bar diameter than that of the bending test. First bend 45 degrees forward, then reverse bend 23 degrees, then reverse bend 23 degrees. After the reverse bending test, no cracks on the surface of the bending part of the reinforcing bar can occur.

surface quality

No cracks, scars or folds are allowed on the surface of steel bars.

The surface of reinforcing bars is allowed to have bumps, but not more than the height of the transverse ribs. The depth and height of other defects on the surface of reinforcing bars should not be greater than the allowable deviation of the size of the part where they are located.

Size, shape, weight and allowable deviation

1) nominal diameter range and recommended diameter

The nominal diameter of reinforcing bar ranges from 6 mm to 25 mm. The nominal diameter of reinforcing bar recommended by the standard is 6, 8, 10, 12, 16, 20, 25, 32, 40 and 50 mm.

2) Allowable deviation of surface shape and dimension of ribbed steel discs

The transverse ribs of ribbed reinforcing bars shall comply with the following basic provisions:

The angle beta between the transverse rib and the axis of the steel disc should not be less than 45 degrees. When the angle is not more than 70 degrees, the direction of the steel bar relative to the transverse rib on both sides should be opposite.

The transverse rib and spacing l shall not be greater than 0.7 times the nominal diameter of the reinforcing bar.

The angle alpha between the side of the transverse rib and the surface of the reinforcing bar shall not be less than 45 degrees.

The total clearance (including longitudinal rib width) between the ends of the transverse ribs on both sides of the reinforcing bar should not be greater than 20% of the nominal circumference of the reinforcing bar.

When the nominal diameter of reinforcing bar is less than 12 mm, the relative rib area should not be less than 0.055; when the nominal diameter is 14 mm and 16 mm, the relative rib area should not be less than 0.060; when the nominal diameter is greater than 16 mm, the relative rib area should not be less than 0.065.

3) Length and allowable deviation

A. Length: Steel bars are usually delivered at a fixed length, and the specific length of delivery should be specified in the contract. When steel bars are delivered in coils, each plate should be a steel bar, allowing 5% of the number of plates per batch (less than two plates) to be composed of two steel bars. The weight and diameter of the stock shall be stipulated through consultation between the supplier and the demander.

B. Length allowable deviation: The allowable length deviation of steel bars when they are delivered according to a fixed length shall not be greater than + 50mm.

C, bending degree and end: bending strain of straight bars does not affect normal use, the total bending degree is not more than 40% of the total length of bars; the end of bars should be sheared straight, and local deformation should not affect use.