Harshvardhan Singh, a senior service engineer at a mining firm, explains that hydraulic oil is widely used in mining equipment’s to transmit power to hydraulic components. Hydraulic circuits of mining vehicles have increasingly become more complex and the number of hydraulic components like hoses and blocks have also increased. Any damage of these hydraulic components can result in huge amount of oil leakage on the surface or in underground. Seepage of oil from hose fittings, adapters and connectors is also commonly encountered in mining vehicles.
Hydraulic oil leakage is one of the most common hydrocarbon spillages encountered in mining machinery or mining vehicles. Oil spillage on ground leads to contamination of soil and this oil flow can also lead to contamination of nearby water body. Apart from effect on environment, oil leakages also contribute to serious fire and smoke hazard. Components like catalytic purifiers, silencers and other components of exhaust line become extensively hot and even a small amount of oil leak can lead to fire or smoke which can create a threatful situation in underground for operator of mining vehicle and for machine itself. Considering the high price of hydraulic oils, oil leakages and oil spillage also hurts the company on cost front as the oil lost is unrecoverable and could not be given for recycling.
Some of the most effective ways of reducing hydraulic oil leakages are mentioned below.
These are widely used to protect hydraulic hoses from any abrasion formed from hoses rubbing against one other or from edges of machine frame. Hose wrappings generally used are made of plastic and is available in different sizes and colours as well for better colour coding of hoses.
Image showing hose wrapping done on hydraulic hoses.
A hose sleeve can be slipped over the end of the hose assembly and clamped at the ends. These sleeves help in containing the thrust of hose burst protecting the machine and the operator. They also act as a shield for hoses against dirt, dust and sunlight and any external abrasion. Nylon sleeves are commonly used in industry. Hose sleeves also come with option of peel able Velcro lining, facilitating hose replacement without requiring disconnection or removal of hoses. Peel able sleeves can also be used to bundle together set of parallel hoses.
Image showing bundle of hose sleeve.
In case of a hose puncture in underground, there is a general practice of replacing the punctured hose with those of any length, as the same hose may not be available onsite at that moment. The replaced hose (with or without wrappings) since oversized is susceptible to rubbing from ground. Hose straps can be used to tie these hoses from machine frame until hose of prescribed length is made available. Hose straps can also be used for containing a bundle of parallel hoses. They serve as a better alternative to cable ties as they are more robust and can be reused.
Image showing hose strap used for binding bunch of hoses.
Quick connect couplings
Mountings and dismounting of platforms or cassettes like water sprinkler, sludge cassette and diesel bowser, requires disengagement of hydraulic hoses from their respective fittings on the PTO block (power take-off) which results in oil spillage. In order to address this issue quick connect couplings can be installed both on cassette hoses and machine’s PTO block to seize oil spillage during mounting and dismounting of platforms. This practice will also reduce the time taken to mount and dismount a cassette.
Image showing quick connect couplings.
At the time of replacement or repair of hydraulic component, the associated hoses have to be disengaged. A small amount of oil always remains in hydraulic hoses and this oil often spills after the hose is disengaged. Hose plugs restricts the oil flow and also protects these disengaged hoses from any contamination or thread damages.
Image showing steel hose plugs inserted in different size hoses.
Apart from industrial solutions, there are certain measures that can be adopted by fluid control specialist or lubrication engineer onsite.
An oil logbook
An oil logbook should be maintained onsite having details of every single litre of oil being consumed in machine maintenance or being topped up for any leakage in any machine, during a shift. The logbook can be made in the form of a hard copy or soft copy. The practice will help in keeping a track of oil consumption in various machines onsite.
Maintaining a stock of high pressure critical hoses
The lubrication engineer with the help of service team or via referring machine manual should have a list of high pressure critical hoses for every machine model and a stock should be maintained at all time. By doing this, in breakdown situations related to hose puncture, the service team could get the prescribed hose of accurate length and doesn’t have to rely on oversized hose. A hose tracker system could further help in calculating life of a particular hose and plan of its replacement can be made in advance
Rerouting and repositioning of critical hydraulic components
Underground mining conditions differ from one site to another. Damage of hoses and blocks are common in underground operations. In accordance to machine history, decisions can be made of repositioning and rerouting of volatile blocks and hoses in order to protect them from any damage.
Author: Harshvardhan Singh
Read the article online at: https://www.globalminingreview.com/special-reports/26092019/putting-a-stop-to-hydraulic-leaks/