30 January 23
Tyre Removal and Replacement Safety
Tyre removal, replacement and inflation risks
The dangers associated with tyre inflation
Truck tyres contain a large amount of stored energy in the form of highly compressed air. To perhaps put that into perspective it can take many minutes for a defective tyre to be deflated before it can be replaced. A sudden rupture of the tyre can release a pressure equivalent to over 34 tonnes of force from compressed air before additional carriage weight is taken into account. We have all seen pieces of truck tyres strewn across the road after a catastrophic incident but if you’ve been unlucky enough to be driving alongside or behind a truck tyre burst, you will have witnessed what that force can do.
With a tuck or van tyre blow out, an explosive force can be released at an angle of up to 45 degrees from the rupture (which is often, but not always, the face of the sidewall of the tyre). This has resulted in numerous fatalities over the years. It is crucial that the airline hose between the clip-on chuck and the pressure gauge/control is long enough to allow the fitter to stand outside the likely trajectory of any explosion during inflation. The fitters are trained to know where is safe and this will vary depending on the size of the tyre and its positioning.
Any tyre fitter will tell you that they prefer the driver to remain in the vehicle cab out of the way representing one less thing for the tyre fitter to worry about. Often the driver will feel they need to stand with the fitter and make conversation and support the guy who has turned out to change a tyre at any time or anywhere to get him back on the road but really this is a mistake and is unlikely to help the fitter go about his task as quickly and safely as possible. A portable safety solution is shown in the picture to enable the fitters to safely inflate the new tyre on the roadside or wherever the tyre failure occurs. This safety device is a lightweight cover that encloses the tyre and wheel rim.
Car tyres generally contain less energy than truck tyres and their size and profile make them less likely to fail catastrophically. Sensible precautions are still required, but a restraining device such as a safety cage is not normally necessary for a car but for a truck it can be essential. The emergency fitter may not have the luxury of being able to use the most appropriate solution if he is attending a tyre repair on the roadside.
Light commercial vehicle tyres or van tyres are now commonly found with pressures around 70psi, which may be sufficient to cause serious injury. Also electric vehicles tend to have tyre with higher tyre pressures too. If so, fitters will use enhanced safety measures such as those required for conventional truck/bus tyres. When inflating above 15psi this will include using a restraint such as the secured horizontal stool and associated clamping mechanism or a strong, firmly-secured cage as illustrated above.
The above diagram shows the likely explosion trajectory for a large tyre during inflation. Typically these tyres, such as agricultural or quarrying vehicles, are too large for the standard safety protective equipment and so may be too big to fit into a restraint. Safe systems of work will need to be devised to ensure that the wheel is restrained and the effects of any explosion are contained safely with everyone staying outside of the likely explosion trajectory. The HSE go on to advise that compressed airlines should have quick-release couplings at both ends to allow the tyre to be deflated from outside the likely explosion trajectory if a fault (e.g. a potential 'zipper' failure of the sidewall) is detected. The valve connector should not require the operator to hold it place.
The value of a gauge or tyre pressure control device could be significant
The pressure gauge/control valve should never be jammed in the open position, nor should 'unrestricted' airlines (i.e. without a gauge or pressure control device) be used to inflate any tyre. For bead-seating of large commercial tyres, removing the valve core allows faster inflation without using excessive pressure. Split rim wheels are now uncommon but they may be found on older vehicles and in some specialist applications. Unfamiliarity can increase the risk of a catastrophic failure so additional training is needed for your maintenance team or call in one of our well trained network fitters.
‘Contains public sector information published by the Health and Safety Executive and licensed under the Open Government Licence’.
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