GB/T 12756-2018Zinc-coated steel wire ropes for high-pressure rubber hose (English PDF)

7.2.2 Mechanical properties

7.2.2.1 The minimum breaking force of steel wire rope shall comply with the provisions of Table 2.

7.2.2.2 The steel wire rope shall be subjected to an elongation test. The elongation at break shall be not less than 2.0%.

7.2.3 Surface quality The surface of steel wire rope shall be free from oil, dirt, and other impurities. The wire shall be free of defects such as scratches, breaks, hard bending, and rust.

7.2.4 Special requirements Through negotiation between the supplier and the buyer, the test of bond strength between steel wire rope and rubber can be carried out. Test items with other special requirements shall be negotiated between the supplier and the buyer.

7.2.5 Rounding off of numerical values The rounding off of numerical values and judgement of testing values for steel wire rope shall be implemented in accordance with the provisions of YB/T 081.

8.2 Diameter inspection

8.2.1 Diameter inspection of steel wire The diameter of steel wire shall be measured in two mutually perpendicular directions of the same cross section using a measuring tool with an accuracy of

0.001 mm. The arithmetic mean of the diameters obtained from the two

9.1.3 From the 1 sample of wire rope taken, 1 core steel wire is taken, and 1 wire is taken in each different layer for the test of zinc-coating weight.

9.1.4 From the 1 sample of wire rope taken, in each different layer, 2 steel wires are taken for the test of mechanical properties (The core wire is not subjected to a test).

9.2 Determination of knot rate of steel wire The knotting tensile test of steel wire shall be implemented in accordance with the provisions of GB/T 228.1.

9.3 Determination of number of torsions of steel wire The number of torsions of steel wire shall be determined in accordance with the provisions of GB/T 239.1. The rotational speed of the torsion test shall be (3±0.2)r/s.

9.4 Determination of zinc-coating weight of steel wire The test of zinc-coating weight shall be carried out in accordance with the provisions of GB/T 1839.

9.5 Determination of breaking force of steel wire rope The breaking force of steel wire rope shall be determined in accordance with the provisions of GB/T 8358.

9.6 Determination of elongation of steel wire rope The method for determining the elongation at break of the wire rope shall be in accordance with the provisions of GB/T 228.1. The gauge length is 250 mm.

9.7 Bond test of steel wire rope The method for determining the bond strength between steel wire and rubber shall be in accordance with the provisions of GB/T 5755.

9.8 Judgement rules and re-inspection

9.8.1 If all tests meet the requirements, the lot (or strip) of wire rope is qualified.

9.8.2 If one or more test items do not meet the specified requirements, it shall, on the same wire rope, take double samples again to carry out the re-inspection of unqualified items. If the re-inspection results meet the specified requirements, the lot (or strip) of wire rope is still qualified. If one or more of the re-inspection results do not meet the specified

11.1.3 For aluminum-plastic composite packing bag, an appropriate amount of desiccant bag shall be placed outside the neutral moisture-proof paper of the steel wire rope, and the plastic film is wound to seal the pack. The packaged wire rope spools are arranged in the aluminum-plastic composite packing bag. After pumping and sealing, USE packing strap to fasten the spool and packing bag to wooden pallet.

11.1.4 For plastic film wrap packing, an appropriate amount of desiccant bag shall be placed outside the neutral moisture-proof paper of the steel wire rope, and the plastic film is wound to seal. The packaged wire rope spools are arranged on a wooden pallet; and the whole spool is wrapped with a plastic film; then, by packing strap, the spool is fastened to the wooden pallet.

11.1.5 Each spool is allowed to be wound with no more than 3 wire ropes. The length of each wire rope and the joint mark shall be indicated.

11.2 Quality assurance period From the date of leaving the factory, the quality assurance period of the wire rope is 1 year without opening the intact pack.

11.3 Storage The wire rope shall be stored in a dry, ventilated room protected from light. It is recommended to store the wire rope at an ambient temperature of 10 °C~40 °C, relative humidity below 60%, and dew point temperature below 20 °C.

11.4 Transport During the transport, the wire rope shall be prevented from being exposed to the sun. The wire rope package shall be prevented from being damaged by impact, and a rainproof oil cloth shall be covered and fastened for transport.