How to Conduct Routine Inspection of Steel Wire Ropes? What Inspection Items Are Involved?

According to the specifications of GB/T 20118-2017 "General Technical Conditions for Steel Wire Ropes," the inspection items and test methods for steel wire ropes are as follows:

1. Measurement of Diameter and Ovality

The diameter and ovality of the steel wire rope should be measured using a vernier caliper with wide jaws. The measurement must be conducted without tension. On two sections at least 1 meter apart, located beyond 15 meters from the end of the rope in a straight section, two mutually perpendicular measurements should be taken at each section. The average of these four measurements is taken as the actual diameter of the steel wire rope. The ovality of the steel wire rope is defined as the ratio of the maximum difference in diameter measured at the same cross-section to the nominal diameter.

2. Measurement of Length

The length of the steel wire rope should be measured without load. For special requirements regarding the measurement of the rope length, the method shall be agreed upon between the supplier and the customer.

3. Surface Quality

The surface quality of the steel wire rope and its strands should be inspected manually by touch and visual examination.

4. Measurement of Weight

The total weight of the steel wire rope includes the weight of the rope, the reel, and the packaging materials. It should be measured using standard weighing equipment. To calculate the unit weight of the steel wire rope, divide the net weight of the rope by its actual measured length.

5. Inspection for Non-Loosening of Steel Wire Rope

Two symmetrically opposite strands at one end of the steel wire rope shall be untwisted to a length of approximately two pitch lengths. After the two strands are repositioned, they should not loosen again spontaneously.

6. Inspection of Surface Quality of Steel Wire Rope

The surface quality of the steel wire rope and its strands shall be verified visually. There should be no quality defects as specified in standard GB/T 21965.

7. Determination of Breaking Force

There are three test methods for determining the breaking force of a steel wire rope: Actual Breaking Force, Sum of Actual Breaking Forces of the Wires, and Calculated Actual Breaking Force. Among these, the Actual Breaking Force is the most commonly used. The method for determining the actual breaking force of the steel wire rope shall comply with the provisions of GB/T 8358. If the measured breaking force has reached or exceeded the minimum breaking force value of the steel wire rope without the rope breaking, the test may be concluded, and it can be confirmed that the rope meets the minimum breaking force requirement. If the rope breaks within a range of six times the rope diameter from the grip and the breaking force does not reach the standard-specified minimum breaking force value, the test is invalid. A new sample may be taken for retesting, but this shall not be counted as one of the four tests.

8. Tensile Test of Strand Wires

The tensile test shall be conducted in accordance with GB/T 228.1. The test shall be performed at a room temperature between 10°C and 35°C. A tensile testing machine shall be used, and it must be calibrated before the test to ensure data stability. The prepared specimen shall be clamped into the testing machine, ensuring that it is subjected to axial tensile force with minimal bending. The specimen is stretched at a specified rate until it fractures or meets the required criteria. Data shall be recorded throughout the test.

9. Reverse Bend Test of Strand Wires

The reverse bend test shall be conducted in accordance with GB/T 238. The test is generally performed at a room temperature between 10°C and 35°C. The specimen shall be as straight as possible and may be manually straightened if necessary, ensuring no twisting or surface damage that could affect the test results. The testing machine shall be adjusted to position the bending arm vertically. The specimen shall be inserted through the lever hole, with its lower end clamped securely, ensuring it is perpendicular to the axis of the cylindrical support roller. The specimen shall be bent 90° and then alternately bent in the opposite direction continuously at a uniform rate, smoothly and without impact, until the specified number of bends is reached or the specimen fractures completely.

10. Torsion Test of Strand Wires

The torsion test shall be conducted in accordance with GB/T 239.1. The specimen shall be as straight as possible and shall be straightened using appropriate methods if necessary. The test shall be performed at the specified room temperature. The specimen shall be placed in the clamps of the testing machine, ensuring its axis aligns with the centerline of the clamps to maintain straightness during the test. The rotating clamp shall be turned at a constant rate within the required range until the specimen reaches the specified number of twists or fractures. Data shall be recorded throughout the test.

11. Test of coating on split steel wire

The coating test shall be conducted in accordance with GB/T 1839. The test solution required for the experiment shall be prepared beforehand. The specimen shall be cleaned with a cleaning solution to remove oil, dust, water stains, and other contaminants, then thoroughly dried. The specimen shall be weighed using a balance, and the weight recorded. The specimen shall be immersed in the test solution and may be agitated until the coating is completely dissolved. It shall then be removed, rinsed under running water, and if necessary, scrubbed with a nylon brush to remove loose deposits. Finally, the specimen shall be cleaned with ethanol, dried quickly, and weighed again using a balance. After weighing, the exposed surface area after zinc layer dissolution shall be measured. The final test result shall be calculated using the specified formula.