What each standard covers

GB/T 8918 is the Chinese national standard, titled steel wire ropes for important purposes, and covers the common constructions used in lifting, mining, ropeways and similar duties. It sets construction, dimensions, material, breaking force and test methods.

ISO 2408 is the International Organization for Standardization's general requirement for steel wire ropes. Its scope is broader, it gives minimum breaking forces by rope class and construction, and many countries and projects cite it as a general technical condition.

ASTM A1023 is the American Society for Testing and Materials specification for stranded carbon steel wire ropes for general purposes. Its construction classes and table system differ from the other two, and it is used on North American projects and in some international purchasing.

The three standards do not replace one another. Which one applies depends on where the equipment came from, what the owner requires and local market practice. A rope can be made to one standard and accepted to another, but the values from the two cannot be mixed.

How the designation is written

A complete wire rope designation covers at least construction, core, diameter, tensile grade, lay direction and surface. GB/T 8918 and ISO 2408 are written in a similar way but not in the same order or with the same symbols; ASTM A1023 leans more on rope class and construction category.

Take a 6x19 class rope, fibre core, 12 mm diameter, grade 1770. A common designation reads 6x19FC-1770-12 mm or a similar combination. Makers may change the order, so rely on the written description when purchasing rather than the code alone.

The construction code has its own traps. 6x19 is a class, and within it sit 6x19S, 6x19W and other sub-constructions with different wire arrangements and breaking forces. With only 6x19 stated, a supplier may deliver the most ordinary variant.

Designation examples and parameter comparisons for the main standards are listed in the steel wire rope data tables

How minimum breaking force is specified

GB/T 8918 and ISO 2408 both give minimum breaking force tables by construction, diameter and tensile grade, usually in kilonewtons. ASTM A1023 gives minimum breaking strength by rope class and diameter, traditionally in pounds or kips.

Table values from the three standards cannot be converted and compared directly. Diameter series, grade series and metallic area assumptions differ; converting units is only the first step, and the construction classes behind the numbers must be aligned as well.

For the same construction, diameter and grade, minimum breaking forces under GB/T 8918 and ISO 2408 may be close but not identical; ASTM A1023 uses coarser rope classes, so the correspondence has to be checked item by item.

Numerical differences between the standards can be compared in the wire rope breaking strength data

Material and tensile grades

All three standards use carbon steel wire as the main material, with tensile grade in megapascals. Common levels include 1570, 1670, 1770, 1870, 1960 and 2160; the higher the grade, the greater the breaking force for the same section.

The grade series are not identical between standards. One standard may treat 1770 as the ordinary level and another may treat 1960 as the high-strength level; state the grade on the order, not just high strength.

Surface condition also affects acceptance. Bright, galvanized and zinc-aluminium coatings have different properties and test methods; coating weight, adhesion and salt-spray requirements must state which standard governs.

Steel grade and tensile grade are not the same thing. At the same 1770 level, different standards may set different chemical composition, diameter tolerance and mechanical requirements; when third-party inspection is required, write the standard number into the contract. Actual performance at the same grade can also differ between standards because the process requirements differ.

Tests and acceptance

The breaking force test is the basic item. A whole-rope breaking test and a wire breaking test are different things: the whole-rope test measures the rope, while the wire test measures individual wire properties and calculates from there.

Beyond breaking force, tests cover diameter, lay length, coating weight, wire wrapping and torsion. How many are required depends on the standard, the order and the duty; ropes for important purposes usually carry a longer test list.

Acceptance rules come from the sampling and judgement clauses in the standard. How many ropes are sampled from a batch, what happens on failure and whether retesting is allowed are all specified; a contract may tighten them but not go below the standard's floor.

Test reports must trace back to heat number and rope section. A pass verdict without raw data gives no way to tell what was tested or by which method.

What a certificate should contain

A complete wire rope certificate should carry at least: standard number, construction, core, diameter, tensile grade, lay direction, surface, length, batch number and date of manufacture.

If a breaking test was done, the certificate should include the measured breaking force, the test method and the test date. Where third-party or class society inspection applies, it should also show the inspection body, certificate number and signature or stamp.

The standard on the certificate must match the standard on the order. Some suppliers deliver product to a new standard with a certificate to the old one, or substitute a company standard for the project standard; such differences are easily missed at acceptance.

A certificate is only a document; the goods still have to be checked. Labels, ink marking, end caps and packing information must agree with the certificate, and any mismatch should be settled before the rope enters store.

Aligning the purchase

Put standard number, construction, diameter, grade, lay, surface, length, termination, certificate requirements and test items into the inquiry in one go. Quote the standard number with its year of issue so the supplier does not price to an old edition.

If the project allows alternatives, write the substitute standard and the equivalence rule into the contract. A verbal agreement that it is close enough leaves nothing to judge against at acceptance.

To request a quotation against project data, use the wire rope quotation page

A wrong standard number or edition costs more than price. A rope made to an old edition may differ from the current one in diameter series or breaking force; if it is rejected after delivery, the buyer carries the delay and the cost.

One-line rule

A standard is a common language, not decoration. State the standard number, edition and grade, and the supplier knows what to make while the inspector knows what to judge.

Each of the three standards has its scope and none is absolutely better. Choose the standard by project requirement and local practice, and choose the product by whether construction, grade and certificate agree; confirming standard and product separately is far more reliable than saying make it to the national standard.

When the standards do not line up, confirm which one governs the project first, then ask the supplier for certificates and test data to that standard. Converted numbers are a reference, but they do not replace the guaranteed value of the other standard.