Wide diameter and long length steel wire ropes, are mainly found on board tanker & bulk carrier vessels.
Of course there are smaller in diameter and length wire ropes used on board all marine vessels, in life craft cranes, cargo cranes etch.
In tanker vessels there is a number of 12 – 16 wire ropes (including spares) for mooring operations, with diameters ranging from 32 -36 mm and lengths from 220 – 280 meters long.
Marine wire ropes are subjected to very demanding operational conditions and harsh sea water attacks.
During operation there are high loads, strong friction points, a portion of the wire is immersed into sea water and sometimes even dragged on seabed.
In open sea, there is frequent sea water attack, resulting in continues wash out of the lubricant from the strands.
As a result , the condition of the wires is usually not good after some time, mostly dew to corrosion. This increases unexpected failures (safety hazard) and maintenance costs.
One common re-lubrication practise, is to manually apply grease (by hand).
First of all, from a technical point of view, this common practice is insufficient & wrong.When re-lubricating a wire rope, it is crucial for the lubricant to reach the core of the rope. If the core is left without lubricant or with insufficient lubricant quantity, there will be increased friction & wear. Also any moisture or water will be trapped inside, causing corrosion to wear the wires from the inside.
When applying grease on a wire rope by hand, the vast portion of the lubricant is left outside the strands of the rope and only a small portion manages to penetrate up to a depth, without usually reaching the core.
The second thing to consider, is that manual re-lubrication is time & labor consuming. The wire rope has to be un-winged from the drum and then to be re-lubricated manually, a quite messy procedure, which also needed to be performed during “smooth sailing time”, dry docking or when the vessel is anchored.
On top of that, the latest 2013 VGP, requires the use of Environmental Acceptable Lubricants (EAL), on all application, that either drip lubricant to the sea, or are immersed into the sea. This of course includes mooring lines (not a necessity for bulk carrier crane’s wire ropes).
The challenge with EAL lubricants, is that they lack in performance compared to “normal” ones, dew to limitation regarding base oil & additives used. Most importantly they need to biodegrade by at least 60% in 28 days, which means more frequent need of re-lubrication.
A solution to the above is a combined use of an automatic wire rope lubricator, an advanced EAL grease and add on actions to reduce sea water wash out (protecting the wires by covering them when not used).
Regarding automatic wire rope lubricators, there are not a lot in the market, only a few and one of the newest and most advanced ones, is Lubrication Engineers Pty Viper system.
It comes in three versions.
The Viper Mark II mini, suitable to lubricate wire ropes with a diameter up to 35 mm (therefore suitable for the majority of wire ropes used on board marine vessels)
The Viper Mark II, that can lubricate wire ropes up to 67 mm in diameter
The Viper Maxi, that can lubricate large diameter wire ropes, from 50 mm to 165 mm.
All units are equipped with a unique seal system, that has several large grooves in which grease is trapped, pressure is build up inside the seal and grease has enough time and volume to penetrate the strands and reach the core of the rope.
There is also a return hole, which is used to calibrate the amount of grease needed and to return any excess grease in a bucket, making the whole process very clean.
Most other systems, either have only simplistic collar seals, or less and shorter in depth grooves.
Viper Mark II & Maxi, also have heavy duty metal scraper plates, that clean the old grease from the surface of the used wire rope and enable easier penetration of the new grease in the rope.
All systems can be equipped with an optional wire rope cleaner, which follows the strand’s groove lines and cleans them.
Viper system is the most advanced and total maintenance lubrication management system for wire ropes.
The pressure build up inside the collar, is strong enough to squeeze out old grease and water from the used rope.
The lubrication procedure is extremelly fast, as speeds up to 2.000 meters per hour can be achieved.
Pic shows the Viper lubricated wires.
Re-lubrication intervals can be safely extended, compared to lubrication by hand, wire rope life will be greatly increased, lubrication procedures will be really fast and much safetier.
Wire rope seen in the above picture, is from a mooring winch of an aframax tanker, that has been lubricated by Viper MKII & Lubrication Engineers’ Wirelife™ 453 grease.After 4 months of operation the lubricant on the wires & the wire rope are in very good condition.
Wirelife™ 453 is an NLGI 0 grease, that has a smooth & tacky texture, is water resistant has excellent pump-ability and maximazes performance results when used in combination with the Viper system.It can easily penetrate the wire strands, is very resistant to sea water attacks, and includes Almasol® LE’s proprietary additive that greatly reduces friction & wear.
It has low aquatic toxicity and it’s variant Earthwise™ 3353 is also EAL certified.
In the following video you can watch a live operation of the Viper system.
For more details on the Viper lubricator, please visit www.viperwrl.com