MDG41 stance

ONCE you’ve seen an image of injury caused by hydraulic oil injection, it’s something you’re unlikely to forget.
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MDG41 specifies that hose assemblers should be broadly competent and well trained

Andy Graham

Published in March 2009 Australian Longwall Magazine

The injuries typically occur when hydraulic fluid escapes under pressure from a “pin-prick” hole in a failed hydraulic hose. The jet of fluid pierces the skin and flesh as easily as a jabbed hypodermic needle.

Oil injection can cause permanent muscle and tissue damage, or worse. According to the New South Wales Department of Primary Industry, there have been two fatalities from injection of high-pressure hydraulics in the state in the past 20 years. Both deaths occurred at longwalls mines.

An analysis of United States and Australian plant and equipment-related mining injuries published by the DPI in 2007 showed 255 longwall hydraulic incidents over eight years. More than 60% of those incidents were caused by hose or fitting failure.

Three quarters were “walkbys” – that is, they did not happen during scheduled maintenance but involved a miner who was unlucky enough to be close by when the hydraulic assembly failed.

A pre-publication draft of MDG41 Guideline for Fluid Power System Safety at Mines was released in August for New South Wales mines, with its 85 pages covering every aspect of hydraulics, from design to testing, installation and training to injury treatment procedures.

While MDG41 will take force in NSW under its more prescriptive approach, Queensland’s Department of Mines and Energy has opted for a different approach.

Queensland Mining Inspectorate Chief Inspector of Coal Mines Gavin Taylor said while Queensland mine operators should be aware of all NSW DPI guidelines, Queensland regulators had chosen a less prescriptive, risk-based approach.

“New South Wales [has] decided to go down the track of mining design guidelines; in Queensland we’ve taken a different approach,” Taylor said.

“Although we have recognised standards – there’s eight of them and we are just about to put the ninth one out – our approach here is very much risk-based. It relates to specific minesites, the hazards they perceive and how they are going to best mitigate them.

“The problem with prescription, as we see it, is that it always becomes the maximum standard. In other words the most people will ever achieve is whatever that prescriptive legislation is.

“What prescription should be is the very minimum, and then you go higher, but that doesn’t happen.”

Taylor said that as well as MDG41 there were a host of other Australian and international hydraulic standards “So all of those need to be taken into consideration when you are actually addressing the hazards that exist at your particular operation,” he said.

Taylor said that even in NSW, MDG41 was a guideline, not a regulation.

“They’ll tell you in New South Wales, ‘if you don’t want to use the guideline that’s up to you, but you need to demonstrate and prove that whatever you’ve done is equal to or better than what the guidelines suggest’,” he said.

“It really comes back to the guys on the minesite making sure they have got their hazards under control.”

DPI NSW confirmed there is no legal requirement to use MDG41 in NSW.

“The mining industry in NSW operates under risk-based legislation, which allows the use of appropriate standards and guidelines for the safe design and use of equipment,” a spokesperson said.

“Feedback from industry indicates the guideline is being widely used, resulting in safety and production benefits.”

MDG41’s prescriptive approach hasn’t met with universal approval from hose and fitting suppliers, particularly regarding the requirement that “hose assemblies shall only be carried out using ‘matched’ hoses and fittings”. MDG41 defines a matched system as “where the hose and fittings (insert/ferrule) are from the same manufacturer [and] are assembled and crimped using the method as specified by that manufacturer”

One supplier we spoke to said that although its hoses and fittings were sourced from separate manufacturers, the supplier had chosen those manufacturers because their products exceeded tough international standards – the same standards that applied to the matched systems approved by MDG41.

Another supplier suggested the tough testing and certification regimes specified in MDG41 may be too expensive to implement – a concern shared by some mine operators.

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