Mines Safety Bulletin No. 126 Inspection and re-certification of a roll-over or falling-object protective structure (ROPS or FOPS)

Background

A roll-over protective structure (ROPS) or falling-object protective structure (FOPS) is used to protect individuals travelling correctly (e.g. seatbelt fastened, doors closed) in the cabin of mobile equipment from the consequences of a roll-over or objects falling on the cabin. 

These structures are designed and destructively tested in accordance with International Standards ISO 3471 and ISO 3449 to provide full protection to the operator. They are certified as compliant by the manufacturer or supplier at the time of delivery. Prior to acceptance of the design of any ROPS or FOPS, destructive tests must be carried out on a prototype of each structure and the test results must comply with the standard.

However, the ISO standards do not provide guidance for ongoing periodic maintenance, inspection or re-certification to ensure the structure continues to provide full protection for the life of the equipment. Also, there is duty holder confusion regarding the application of some standards and the Mines Safety and Inspection Regulations 1995.

Regulatory requirements for a ROPS or FOPS

The requirements applicable to these structures under the Mines Safety and Inspection Regulations 1995 are described below. 

• Powered mobile plant must be fitted with appropriate operator protective devices if there is an otherwise uncontrolled risk of exposure to overturning or falling objects. [rr. 6.4(2)(b) and (c)]
• Earth-moving machinery used at a mine must be fitted with a ROPS that complies with Australian Standard AS 2294. [r. 4.15]
  Note: The latest (1997) version of this standard effectively adopted the ISO standards. The Mines Safety and Inspection Amendment Regulations 2012 (gazetted in January 2013) adopted the latest versions of Australian Standards, therefore AS 2294:1997 is now mandatory for equipment manufactured after January 2013.
• The definition of "earth-moving machinery" is extended to include earth-moving machinery that has been modified to perform other service functions (e.g. off-highway haul trucks converted to water trucks). [r. 4.15(1)]
  Note: Because regulation 4.15(1) excludes earth-moving machinery that is only used underground, regulation 4.15 only applies to "quarry operations" as defined in Section 4 of the Mines Safety and Inspection Act 1994. This includes any associated roads, ore stockpiles, waste dumps and tailings dams and all areas of the mine where earth-moving machinery is
  used for mining production or development work.
• Depending on risk assessment, on-highway type trucks used in quarry operations, particularly as water trucks, may also be expected to have a ROPS. [rr. 6.4(2)(b) and (c) may apply; refer to guidance in Mines Safety Bulletin No. 28 Rollover protection for surface earth moving machinery]
• Any agricultural tractor used at a mine must have a ROPS that complies with AS 1636. [r. 4.15] 
• All trackless underground mining equipment (with an on-board operator) and underground service units must be fitted with a FOPS that complies with AS 2294. [r. 10.46] .

The regulations require a ROPS or FOPS to be fully functional whenever the vehicle is in service, regardless of age or condition. It is expected that, as part of the mining operation’s safety management system, a ROPS or FOPS is appropriately inspected and maintained to confirm its function is not impaired.

• If the ROPS or FOPS on a vehicle is structurally damaged, the vehicle must be withdrawn from service until the structure is repaired or replaced to a fully functional condition so that it conforms with AS 2294. [rr. 4.15 and 10.46]
• Whenever any plant is damaged to the extent that its function or condition is impaired and hazards increase, the damage must be assessed by a competent person, and any repair, inspection and, where necessary, testing is carried out by a competent person. [r. 6.22]

Summary of hazard

A ROPS or FOPS provides protection during a roll-over or when objects (e.g. rocks) fall on the cabin because the structure and its mountings absorb energy. However, if the structure’s integrity is compromised, the cabin may be damaged or crushed in an incident, and occupants harmed.

Contributory factors

Reduced performance

The performance of a ROPS or FOPS may reduce over time due to factors such as:

• corrosion arising from age and exposure to moisture (e.g. water trucks, underground equipment) or corrosive dust (e.g. nickel sulphide ores) 
• excessive flexing of vehicle chassis leading to metal fatigue (e.g. poor road conditions, cracked welds)
• exposure to excessive vibration (i.e. metal fatigue)
• unauthorised modifications to the structure
• general damage to the structure (e.g. impacts, accident damage)
• vehicle fire or excessive heat
• a ROPS or FOPS relocated from an old vehicle to a new vehicle with a higher mass (i.e. may not be fit for purpose)
• incorrect re-installation of a ROPS or FOPS when relocated from an old vehicle to a new vehicle.

Lack of understanding of requirements

Some common sources of misunderstanding and confusion in industry are discussed below.

• Earlier versions of the ISO ROPS standards only included criteria for "mid-range" sized earthmoving machines. In the past, therefore, some very small and very large machines were often delivered without a ROPS, or with a ROPS that was not certified to the standard. 
  The latest versions of the standards now include criteria for all sizes of machines. The current version of AS 2294 and the reference ISO standards were in place in January 2013 when the Mines Safety and Inspection Regulations 1995 were amended to update Australian Standards. This means the later criteria are enforceable for machines purchased after January 2013. 
• AS 2294.1:1997 effectively adopted the ISO standards. However, since 1997, Parts 2, 3 and 4 of AS 2294 have been discontinued. Because the regulations only refer to AS 2294, some duty holders have interpreted that the ISO standards are not mandatory. However, AS 2294 Part 1 (which has not been updated) is still in place and adopts the ISO standards.
• As neither the Australian nor ISO standards recommend any periodic inspection intervals, some duty holders only inspect a ROPS or FOPS when damage or incidents are reported. In some circumstances, this may not be a sufficiently safe system of work.
• There is uncertainty about what is considered to be "minor damage" not requiring immediate action to repair. AS 2294 defines minor damage as deformations that are "well outside the deflection-limiting volume with no damage to welds or any cracks in the structure". ISO 3164 has further guidance on determining the deflection-limiting volume.