Lubrication of Lifting Chains
The life of an adequately lubricated chain is estimated to be 60 times longer than that of a dry running chain. Even temporary dry running will shorted chain life considerably.
By correct and adequate chain lubrication the problems below are significantly reduced if not prevented from occurring at all:
- Noisy operation
- Surface rust
- Joint rust
- Stiff joints
- Twisted pins
- Loose pins
- Broken link plates
- Broken pins
- Unacceptable chain elongation
60% of all chain defects can be identified as relating to incorrect lubrication. It is common for users to assume they have lubricated their chains well but nevertheless friction corrosion, twisted pins, metallic friction, stiff joints, noisy operation and pitting still occur. This is always the case whenever the applied lubrication product adheres to only the exterior and does not penetrate into the chain joints. This situation occurs whenever the lubrication product is not capable of flowing between the link plates and pins. Ensuring that the lubrication is applied to chain when it is in a slack condition will avoid this problem.
Correct cleaning of chains – If a chain has become so soiled during operation that thorough penetration of the lubricant is not guaranteed then the chain must be cleaned. This must be done only with a paraffin derivative. It is not advisable to clean with cold cleansing agents or even caustic and acidic agents. These may lead to direct chain damage.
Chain cleaning using steam jet equipment – Substantial soiling of lifting chains may occur at short intervals under specific conditions of use. In these circumstances it may be necessary to clean the chains with steam jet equipment. This should be done exclusively without the use of aggressive or caustic cleaning agents containing chlorine. Pure water or steam is the agent that will be produce the least damage. It is necessary to understand that after such cleaning the chain has not only been thoroughly cleaned but also totally ‘degreased’. In this condition, particularly owing to the presence of water, the chain is subject to extremely rapid and dangerous corrosion. A film of water will remain longest in the chain joint, i.e. between the contact faces of the link bore and pin surface producing corrosion, stiffness and pitting. All experts generally accept that such corrosion is the principal cause of premature chain damage and lifting chain failure.
Suggested cleaning method when using jet equipment – The following procedure is suggested if such cleaning methods can not be avoided:
- Cleaning – Clean chain with steam or hot water, using no additives whatsoever
- Compressed Air – Immediately after cleaning, remove the water from the surface of the chain and from the inside of the joints using compressed air. Move the chain several times while doing so.
- Re-lubricating – Ensure that chain is in a slack condition and immediately spray or brush with preservative and lubricant. When doing so move the chain an adequate number of times to ensure the lubricant will actually be capable of penetrating the joint. It is recommended that the chain be fully immersed in the lubricant to give the most satisfactory penetration.
Products to be used – It is suggested that the following characteristics are required for a good standard of lubrication:
- Adequate corrosion protection and lubrication ability
- Ability to penetrate through water
- Continuously viscous after application
- Good adhesion properties
- Layer thickness and protective film able to withstand later mechanical aggression – such as pelting rain and hail.
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