Material & Surface Finish

Correct selection of raw material is essential in order to achieve the required breaking force and mechanical characteristics.

Our wire ropes are manufactured using a high carbon content, patented rod, which allows both wire strength and ductility to be achieved, without the adoption of extreme rope grades.

The rod is subjected to a drawing process, which consists of a number of passages through a series of tungsten carbide dies with a gradual diameter reduction. During this process, the metallurgical structure of the rod changes from a very thin perlite pattern to well aligned fibres with high tenacity and strength.

The combination of carbon content and amount of drawing is determined depending on the specific application of the wire rope and the required mechanical characteristics.

Steel has to be protected against corrosion and consequently bright ropes, which are still popular for some applications, have a very limited use in oil and gas applications, while zinc coating is highly recommended for the marine environment.

The quantity of zinc which has to be applied to wires is regulated by EN10264-2 – Steel wire and wire products – Non ferrous metallic coatings on steel wire – Zinc or zinc alloy coatings.

For rope used within the oil and gas industry, the typical zinc thickness is approximately 20 to 25 microns, which complies with class B.

Zinc is applied by a hot dip process in order to avoid hydrogen embrittlement typical of electrochemical plating. Hot dip galvanizing creates a tight connection between zinc and steel, virtually alloying them in one unique entity.

For severe environmental conditions, improved surface finishing based on zinc aluminium alloys can also be adopted.

It must be emphasised that surface finishing has to be adopted in conjunction with adequate lubrication and maintenance levels in order to preserve wire rope performance.

Definitions:

Finish and quality of coating: The condition of the surface finish of the wire e.g. uncoated (bright), zinc coated, zinc alloy coated or other protective coating and the class of coating, e.g. class B zinc coating, defined by the minimum mass of coating and the adherence of the coating to the steel below.

Mass of coating: The mass of coating (obtained by a prescribed method) per unit of surface area of the uncoated wire, expressed in g/m2.