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                                                                                                    MDG 41
MDG 41 is a document which was created in response to an increasing number of incidents involving high-pressure fluid injection injuries on mine sites. In response to this, the NSW Department of Primary Industries (DPI) established a joint committee with involvement from the Mining Industry, Equipment Manufacturers, Repairers, and Suppliers of Fluid Power components in order to formulate a ‘best practice’ document. The result is Mechanical Design Guideline Number 41 (MDG 41).
The Mechanical Design Guidelines are a series of tools to assist companies in achieving compliance with the OH&S Act and Regulations through implementing industry best practices. We all have a duty of care to assess the hazards in the workplace and to implement systems and programs in order to eliminate or minimise the risk they present.
These documents prompt the review of many areas in fluid power systems that may present a risk and sets out guidelines of how they should be addressed using ‘best industry practice’.
RYCO have a commitment to OH&S and the MDG’s, and as such have developed products and strategies to assist our customers in understanding the requirements of the guideline. We can assist you to adopt the recommended practices outlined in MDG 41 and MDG 15.
MDG 15
MDG 15 is a guideline for all mobile or transportable plant used at mines, and refers to MDG 41 for fluid power systems. It has further requirements in relation to the routing of hosing.
Today’s hydraulic systems are required to withstand tremendous pressures. This means that the attachment of a fitting to the end of a hose becomes more critical. This may be a simple operation, but it is a complex engineering solution.
International Hose standards specify a set of materials and tolerances, such as internal and external dimensions and reinforcement types and patterns. The reality is that while these standards are adhered to by all manufacturers, the tolerances themselves are so broad that if the entire allowable tolerance was used in manufacturing, users would encounter a high failure rate due to hose and fitting tolerance mismatching. High quality hose manufacturers have to adopt their own tolerance limits which are often at least half of the allowed range.
This is where “Mixing and Matching” becomes an issue: Component manufacturer ‘A’ could produce parts on the lower limits of the tolerance, and manufacturer ‘B’ is on the upper end of the tolerance. If a fitting from ‘B’ was put on a hose from ‘A’ at the specified crimp diameter of ‘B’, there would be little chance of adequate fitting retention, which would most likely result in failure. Similarly if a fitting from ‘A’ was assembled to a hose from ‘B’ the likelihood is that the inner tube of the hose would be over-compressed or the hose reinforcement could be cut, again resulting in premature failure.
MDG 41 stipulates hose assemblies shall only be carried out using “Matched Hose and Fittings” (MDG 41 Clause MDG 41 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” (MDG 41 Clause 1.6.13).
Suppliers of manufactured hydraulic hose assemblies must be able to guarantee that the hose and fittings used are matched. RYCO products provide our customers with a matched system. Our design teams create and stringently test the hoses and fittings together to ensure optimum performance and reliability. All this is achieved using RYCO’s assembly methods which are reliable and easy to follow.
MDG 41 - CLAUSE 1.6.13
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.

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