What is the impact of environment on leaf chain wear life?
The environments in which leaf chain mechanisms operate can differ widely. And the harsher the environmental conditions, the greater the impact will be on the safety, efficiency and longevity of the chain.
Chain that is used in forklift trucks, for example, can often be compromised by the effects of outdoor moisture, highly corrosive atmospheres or abrasion from sand or grit.
In this blog post we explore the primary environmental factors that can affect leaf chain wear-life and the importance of regular leaf chain inspection in ensuring the optimum performance of your materials handling equipment.
How environment affects leaf chain
Each specific forklift truck chain application will need to be evaluated for risk, according to the extent of environmental exposure it is subject to and the area in which it operates.
There are four key environmental conditions that impact on chain wear-life:
1) Moisture
Moisture produces corrosive rusting (or oxidisation of the chain steel) which can lead to a reduction in the strength of the leaf chain through the processes of pitting and cracking.
2) Low Temperature
When a lift truck’s daily activity involves constantly moving in and out of cold stores, condensation can form on the outer and bearing surfaces of the chain.
This condensation can cause stiffness and eventually result in corrosion fatigue cracking which will reduce the service life of a forklift truck chain.
3) Chemical solutions or vapours
Chemical solutions and vapours can corrode leaf chain components, anchor pins, anchor bolts, anchor blocks and cause microscopic stress cracking.
Depending on the extent of exposure, these cracks can propagate across the forklift truck chain leading to complete, and abrupt, failure.
4) Abrasives
Accelerated wearing or scoring of the pin surfaces and link plate apertures will inevitably lead to reduced forklift chain strength.
The bearing surfaces of these articulating members are not readily accessible which means that the wear is not usually visible – so the extent of chain wear should be regularly inspected using a precision tool such as a Chain Wear Gauge.
Leaf chain lubrication
Adequate lubrication is another key factor that will have a significant effect on the wear life of leaf chain. Forklift chains that operate outdoors where they are vulnerable to dirt and debris, in cold-stores where they are subject to condensation, or in highly corrosive environments will need to regularly washed and re-oiled to ensure optimum performance.
The life of a sufficiently lubricated leaf chain has been estimated to be sixty times longer than that of a dry running chain. Even temporary incidents of dry running can result in a significantly reduced service life.
Leaf chain inspection guidelines
It is vital to frequently inspect leaf chains and to establish a schedule for their replacement, to avoid the risk of forklift truck chain failure.
As a minimum, the frequency of your forklift truck inspections will need to comply with the minimum legal requirement as detailed in LOLER 98, regulations 9, 10 and 11, for the Thorough Examination and Inspection of Industrial Truck Leaf Chain.
It is also recommended that forklift truck users familiarise themselves with all the relevant Health and Safety guidance notes related to chain, and in particularPUWER 98.
Others guidance documents published by the British Industrial Truck Association (BITA GN15 & GN28) and the technical bulletins of Fork Lift Truck Association (FLTA TB 02, 05, 08 & 09) will also be useful resources.
By its very nature, a forklift truck leaf chain should be viewed as an expendable item – which means that a safe leaf chain replacement schedule needs to be established.
It is recommended, for example, that forklift truck chains that operate in extreme or challenging environments have their leaf chains and leaf chain anchor pins replaced after a maximum of 4000 operating hours – or every two years (whichever comes first).
If a lifting mechanism uses a single leaf chain (e.g. a free lift section), any leaf chain anchor bolts should also be replaced together with the chain.
The environments in which your forklift trucks operate can have a significant impact on the efficient running, endurance and safety of your leaf chain mechanisms. Being mindful of environmental conditions, maintenance of equipment and the conducting of regular inspections can all play a vital role in ensuring optimum performance and extending service life.
