1. Hydrostatic (water pressure) test
Equipment and environment:
Use calibrated pressure pumps and pressure gauges with appropriate ranges, and the accuracy meets the standard. The test environment is stable, and the test water is clean fresh water without impurities and microorganisms.
Steps:
Seal both ends of the steel pipe and connect the pressure pump to inject water and exhaust. Increase the pressure at a uniform rate according to the standard, if not exceeding 3.5 MPa/min. After reaching the test pressure, stabilize the pressure for no less than 10 minutes, and check for leakage, sweating or abnormal pressure drop.
Judgment:
No leakage during the pressure holding period, and the pressure drop is within the allowable range (such as not exceeding 3% of the test pressure).
2. Flattening test
Equipment and specimen:
High-precision press, flat and parallel flattening plates. Cut 40-100mm specimens, and both ends are flat and perpendicular to the axis.
Steps:
Place the specimen between the flattening plates, and the weld is 90 degrees to the pressure direction. Apply pressure at the standard rate until the distance between the plates reaches the specified value (depending on the ratio of outer diameter to wall thickness).
Judgment:
When flattened, there are no cracks, fractures and other defects, which is qualified.
3. Bending test
Equipment and specimen:
Testing machine with adjustable bending angle and mandrel radius. The specimen length is more than 12 times the outer diameter of the steel pipe, and the surface is smooth and defect-free.
Steps:
The specimen is placed on the testing machine, the weld is placed on the neutral axis or in a specific position according to the standard, and bent according to the specified angle and radius, with a moderate and stable speed.
Judgment:
If there are no cracks, delamination and other defects in the bending area, it is qualified.
4. Flaring test
Equipment and specimen:
Standard conical flaring tool and fixed steel pipe workbench. The specimen is 50-100mm long, with both ends flat and burr-free, and the open end is fixed upward.
Steps:
The conical tool is slowly pressed into the open end to expand the outer diameter according to the standard (such as the expansion rate of 10%-30%).
Judgment:
If there are no cracks, peeling and other defects after expansion, it is qualified.
API 5L X52 Seamless Carbon Steel Pipe
