WIRE ROPE LUBRICATION & PRESERVATION
Lubrication & Preservation
Wire Rope
Introduction
Steel wire ropes are used in a wide variety of applications and environments.
Many ropes are of complex construction and designed to meet specific engineering applications.
The ultimate working life of a wire rope is dependent upon many factors, but effective in-service lubrication and corrosion protection are fundamental parts of planned maintenance.
The selection of the correct lubricant designed to meet the requirements of the application, environment and rope design is vital if maximum benefit from in-service lubrication is to be obtained.
Bridon gives advice on the specific rope lubricants best suited to any application.
High pressure lubricators, which greatly assist both cleaning and re-lubrication are available and Bridon will advise on their suitability for any particular application.
General Information
Most ropes have a lubricant incorporated during manufacture, to prevent corrosion during shipment and storage, and to provide internal lubrication during the early part of the rope’s working life.
However, wire ropes are like any other machine and lubrication and corrosion protection must be maintained for optimum life to be achieved. Such service maintenance is termed re-lubrication.
It is important that the lubricant used are formulated specifically for wire rope maintenance and are compatible with the manufacturing lubricant. The particular environment and application must be considered in order to select the most appropriate type of lubricant. For example, modern multi-strand ropes require a lubricant with good penetration properties which will fill the small interstrand spaces and penetrate as far into the rope as possible.
- Ropes working in industrial outdoor environments where corrosion is the predominant cause of deterioration. Internal corrosion leading to fatigue initiation is the major concern in these applications.
- Ropes working on friction hoists. Lubrication to combat corrosion and internal wear is necessary without risking the loss of frictional grip.
- Ropes working over sheaves but not subject to heavy surface abrasion or corrosion.
- Ropes working in conditions of heavy wear. Here abrasion is the predominant cause of failure.
- Standing ropes and working ropes subject to heavy loading in marine or other corrosive environments.
In this case corrosion and abrasive wear combine to form the major causes of failure.
These wide variations in working conditions call for fundamentally different types of lubricant. Specific properties are needed to achieve optimum rope performance. In some cases, a combination of a solvent based corrosion preventative, designed to achieve penetration and moisture displacement, followed by the application of a heavier protective coating can be used to achieve optimum corrosion protection combined with good lubrication.
- For maximum benefit, the lubricant should be applied as soon as the rope is put to work.
- The lubricant should be re-applied at regular intervals, preferably before the rope shows signs of corrosion or dryness. Frequency of application depends on the actual site conditions and the periods indicated in each section in this information sheet are for guidance only.
- If the existing lubricant on the rope is heavily loaded with foreign matter (dirt, sand, grit etc.), the rope should be cleaned before fresh lubricant is applied. Pressure cleaning and relubricating systems are the most effective methods.
- The loose products of corrosion should be brushed off before fresh lubricant is applied. If the external wires in the rope are heavily corroded, or if there is reason to believe that there is severe internal corrosion, the rope must be examined by a qualified person and, if necessary, discarded.
- The lubricant and application should be such that a thin, even adherent coat covers all the wires in the rope.
It must be emphasized that these comments are general recommendations, applicable to round, triangular strand and multi-strand ropes used in similar applications to those indicated. They do not apply to certain specialized ropes such as locked coil ropes, where specific recommendations can be made on request. Extensive research has been carried out into lubrication of ropes under a wide variety of usages and environmental conditions and Bridon will be pleased to advise rope users on specific problems.
Selection Of In-Service Lubricants
Ropes Working in Industrial or Outdoor Environments
A. Ropes working in industrial or outdoor environments
Typical examples are:
- MOBILE AND TOWER CRANES
- CONTAINER CRANES
In such applications there is always the possibility of internal as well as external corrosion. Of the two the former is more serious because it is hidden. There is the possibility of moisture entrapment if an incorrect lubricant is used, as it is usually difficult to dry the rope prior to dressing.
It should be noted that many apparent fatigue type failures in such applications are initiated by corrosion.
The lubricant must:
- Penetrate inside the rope – the most difficult part of the rope to inspect
- Displace moisture from internal and external surfaces
- Give good corrosion protection, internally and externally
- Be resistant to wash-off and emulsification
- Not lead to build-up with repeated applications
The best lubricant for such applications are solvent based, which after evaporation leave a semi-dry waxy film which is reasonably thick (0.01 mm typically). These lubricants must have specific anti-corrosion properties, they must be tenacious and the resulting film should be semi-dry to minimize pick-up of abrasive particles e.g. sand, which can combine with an oil lubricant to promote internal wear.
Lubricants containing chlorinated hydrocarbon solvents such as trichlorethylene or carbon tetrachloride are NOT recommended.
Lubricants containing ‘dry lubricants’ such as molybdenum disulphide and graphite are NOT recommended as these compounds tend to dry out leading to surface film breakdown and consequent exposure of wire surfaces to the atmosphere.
Dressings should be applied by drip feed, spray or pressure application, usually at no more than monthly intervals.
Ropes Working on Friction Hoists
B. Ropes working on friction hoists
Typical examples are:
- ELEVATORS
- FRICTION HOISTS
- CAPSTAN WINCHES
These ropes are subject to corrosion and wear and yet application of conventional lubricants can lead to severe loss of traction resulting in slip.
Traditionally these ropes are lubricated very little in service due to the conflicting problems of lubrication and slip. Lubricant applied during manufacture is kept to a minimum for this reason.
The only lubricants satisfactory for this application are those designed to provide corrosion protection and internal lubrication while minimizing loss of frictional grip or actually increasing the coefficient of friction.
A solvent based dressing which deposits a thin slipresistant semi-dry film is the best solution.
In addition, moisture displacement and the prevention of excessive lubricant build-up are important. Lubricants should be applied by brush, spray or automatic feed, at monthly intervals.
Unless a specific anti-slip dressing is used, great care must be taken to ensure that slip is not generated by over application.
Ropes Working Under Conditions of Low Abrasive Wear and Corrosion
C. Ropes working under conditions of low abrasive wear and corrosion
Typical examples are:
- ELECTRIC OVERHEAD CRANES
- WIRE ROPE HOISTS
- INDOOR CRANES
- SMALL EXCAVATORS
- PILING, PERCUSSION AND DRILLING EQUIPMENT
Such ropes are subject to internal wear, leading to fatigue failures of wires.
For these applications the best lubricants provide maximum lubrication internally and externally.
Lubricants using a mineral oil base, SAE 30, are generally accepted as the best. However basic oils provide very little corrosion protection and are subject to excessive run-off and fling-off. It is recommended, therefore, that a specific oil based rope lubricant with a tackiness additive and anti-corrosion properties be selected.
Compounds containing ‘dry lubricants’ such as molybdenum disulphide and graphite have been shown to provide no increase in fatigue life in wire ropes over and above that provided by mineral oils. Application should be by brush, spray or drip feed whenever the rope appears dry.
Ropes Working in Conditions of Heavy Wear
D. Ropes working in conditions of heavy wear
Typical examples are:
Onshore:
- EXCAVATORS
- WINCHES
- HAULAGE APPLICATIONS
Offshore
- MOORING SYSTEMS
- DREDGERS
Under these conditions the primary requirements for rope lubricants are:
- Good adhesion to the rope to prevent fling-off and loss of coating.
- Resistance to removal by mechanical forces. A lubricant that dries and cracks will scrape off or fall off in bending. Some bituminous compounds can ‘cement’ broken wires in place making inspection more difficult.
- Good anti-wear properties.
In addition the lubricant must be resistant to moisture, emulsification and ultra-violet degradation.
Good corrosion protection is essential, particularly in offshore conditions.
Further preferred properties are ease of application and a stable physical nature over a wide temperature range.
The lubricants are petroleum-gel based, with thixotropic characteristics. Such compounds provide good lubrication over a wide range of temperatures and do not crack or craze in ultra-violet light. Their thixotropic properties enable good adherence and continuity on the side of the rope, combined with good lubricity under shearing stress.
A further feature of thixotropic lubricants is the ease with which they penetrate the rope through the use of pressure lubricators.
Such lubricants are designed for long working life and infrequent application. Relubricating should take place as required depending upon the intensity of usage and the severity of the environment.
Standing ropes and working ropes subject to heavy loading in corrosive environments.
Typical examples are:
Onshore:
- GUY ROPES
- PENDANT ROPES
Offshore:
- TOWING CABLES
- CRANES AND DERRICKS
- TRAWL WARPS
Under these conditions ropes are subject to extended periods of corrosive attack in standing situations. In some applications, such as offshore cranes, the ropes are required to undertake heavy duty lifting work after extended periods at rest.
The primary requirements for rope lubricants in such applications are:
- High corrosion protection
- Long term stability of the lubricant
- Good adhesion to the rope, even when wet
- Resistance to wash-off, emulsification and mechanical removal
Only lubricants which provide high corrosion resistance should be used and the lubricants should remain stable over extended periods of time over wide temperature ranges.
Resistance to cracking and ultraviolet degradation is necessary for long term protection.
Lubricants with similar characteristics to those in section (d), but with high corrosion protection characteristics, are recommended.
Traditional bituminous compounds are not recommended as service lubricants because they can trap moisture in the core, and may not act as lubricants when a rope is put to work after extended periods in a static situation, due to hardening. Such compounds are only effective as lubricants when applied during manufacture, usually heated and under pressure.
Thixotropic gels are the most suitable lubricants as they provide excellent protection against the environment, good lubrication under dynamic operation and operation and return to a semi-solid coherent lubricant at rest. Re-lubrication of a used rope can often be improved by an initial application of a solvent based corrosion preventative lubricant which penetrates and displaces moisture in the rope.
Lubricants Available
There is a wide range of compounds on the market. Some of these are specific to wire rope applications and others are multi-purpose products which can offer some benefits to wire ropes.
Bridon’s own brand of wire rope lubricants, the BriLube® range, has been developed especially for wire rope. Based upon extensive experience in wire rope usage, there is a BriLube® product to meet most applications mentioned in this document.
Detailed technical data, catalog and supplies of BriLube® are available from authorized Bridon distributors.
FOR Tower Cranes, Mobile Cranes, Dockside Cranes, Fishing Ropes
BRILUBE 30-a semi-dry thin film lubricant with excellent penetration and corrosion resisting properties.
Formulated for frequent use in harsh working conditions, whilst minimizing lubricant buildup and abrasive particle contamination.
BRILUBE 30 is recommended for general outdoor use where corrosion is a major contribution to rope deterioration.
FOR Lifts and Elevators, Friction Hoists
Formulated for use where frictional grip is vital, it provides internal lubrication whilst avoiding excessive build-up with repeated applications.
BRILUBE 40 is recommended for use on lifts, elevators and similar friction driven rope installations.
FOR Indoor Cranes, Piling Applications, Small Excavators
BRILUBE 50 is recommended for overhead cranes, hoist ropes and similar working ropes, where fatigue is the major factor in rope deterioration.
FOR Excavators, Guy Ropes, Winch Ropes
BRILUBE 60 is recommended for outdoor use providing effective lubrication and corrosion protection where only infrequent lubrication is possible.
FOR Offshore Cranes, Rigging, Mooring & Towing Cables, Fishing Ropes
Formulated for long life on static or dynamic ropes in highly aggressive environments. BRILUBE 70 is recommended for use in off-shore and other hostile environments where effective lubricant and optimum corrosion protection are vital.
FOR Offshore Installations, Lake and River Ferries, Dock Facilities, Water Treatment Operations
Formulated for heavy duty applications in environmentally sensitive environments.
BRILUBE 90 is recommended for use wherever rope lubrication is a problem due to environmental concerns.
The BRILUBE range can be applied by dipping, brushing, spraying and BRILUBE 60, 70 and 90 are particularly suitable for use with High Pressure lubricators due to their good pumping characteristics and non-drying nature.
BRIDON recommends the MASTO High Pressure lubricator, an effective, reliable and economical system, ensuring maximum penetration of lubricant with simultaneous removal of most contaminants.
MASTO systems are available from all BRILUBE stockists for ropes up to 3 ins diameter, and will lubricate up to 150 feet per minute, minimizing downtime and waste, while maximizing the proven benefits of in-service lubrication.
The BRILUBE range of advanced wire rope lubricants has been developed to promote longer safe-working life through effective lubrication and corrosion protection.
BRILUBE® APPLICATION SYSTEMS
PORTABLE PRESSURIZED SPRAYER
This handy pressurized spraying unit consists of a pressure-tested galvanized steel vessel with pressure gauge, pump, relief valve, 2 meters of reinforced hose and 350mm lance with trigger control and built-in filter. All seals are of solvent resistant nitrile material.
The special funnel shaped head ensures easy filling and protects the gauge and valve.
The unit can be carried by either the handle or the shoulder strap and operates at up to 80 p.s.i. (5.47 bar) for maximum penetration of the dressing, making the unit ideal for the application of BRILUBE onto winches or crane drums.
All units are supplied complete with operating and maintenance instructions and a full list of spares which are readily available.
MASTO™ POWERED APPLICATION SYSTEMS
These systems operate by forcing the dressing into the rope under high pressure, while simultaneously cleaning the rope and removing moisture, residual dressing and contaminants.
The MASTO system, approved by BRIDON, is suitable for ropes from 4mm to 35mm, and 36mm to 76mm diameter.
The pressure heads are light in weight, easy to attach and effective in use with most rope constructions. The low cost seals are easy to replace and have long operational lives.