091016 Alert Stored Energy En

OCTOBER 2009

SAFETY ALERT FLASHRISKS LINKED TO STORED ENERGY

Group Communications – to Sr Management, BU managers, Health & Safety & Communications networks for posting and discussion at all sites

Several accidents have occurred in the past due to stored energy. The EI standard will be focussing on the importance of releasing the stored energy before any work.For example, one of the most dramatic took place in LICHTENBURG (South Africa Cement) in September 2008 which took the life of an electrician. Most of the root cause analyses after these types of accidents show that being unaware of the risk of sudden movements of machinery is one of the main causes. Accidents could happen because the stored energy is not obvious (the machine may be stopped and even locked out). Stored energy could be present in the following forms and could result in serious accidents or fatalities: The weight of the equipment or a piece of the

equipment The weight of the material in a kiln or in a mill

under load The weight of the material in a bucket

elevator or in an inclined conveyer belt suddenly stopped

The weight of a piece of equipment unbalanced by the intervention (partial dismantling of hammers on a crusher or buckets on an elevator…)

Compressed fluids (air, oil, liquid fuels…) Electrical energy stored in batteries or

capacitors (electro precipitator not grounded…).

The release of this stored energy represents a potentially fatal hazard for the people working on such equipment (unexpected move, electric flash…).The lock-out procedure should include in this case a step to bring the equipment into a zero-energy state.

Some examples for complementary operation after lock-out Before any intervention: Put the arm of the reclaimer on the material stock pile

or on the ground before intervening Balance the kiln and the mill in order to prevent

movement Unload the compressed fluids or isolate the circuits

under pressure by opening a purge valve and by discharching the pressure with the tap below the isolating valve of the circuit under pressure

Ground the electrical circuit or energized equipment.

When the zero-energy state cannot be reached, take appropriate measures. For example: Block the equipment appropriately (unbalanced

crusher rotor, equipment being dismantled…) Block systematically the mobile piece of a bucket

elevator or an inclined unbalanced belt conveyor which can not be unloaded or that will be unbalanced by the work (dismantling of bucket, intervention on the belt of the conveyor …).

Such stored energy risks can be prevented by: Using this alert to raise general awareness around

stored energy Ensuring measures are taken into account in the risk

analysis to remove or isolate the stored energy. Follow the mandatory LOTOTO sequence from the

LOTOTO Advisory (including Step 6: Zero Energy State) A list of stored energy possibilities on all the pieces of

equipment of the plant/site which will be used as a support for field training during the roll-out of the Energy Isolation Standard.

A risk analysis is essential to identify such stored energy situations before any intervention takes place (Remember this risk analysis procedure is mandatory before all interventions including those carried out by contractors. All team leaders must be reminded of this).

OCTOBER 2009

SAFETY ALERT FLASHRISKS LINKED TO STORED ENERGY

Pictures of the Lichtenburg plant below which illustrate the difficulty in identifying the lethal risk linked to stored energy for what is considered to be a simple task at a material reclaimer.

Group Communications – to Sr Management, BU managers, Health & Safety & Communications networks for posting and discussion at all sites

The disintegrated low speed reducer which controlled the boom incline

The reclaimer is in working position. Purpose of the task: change the motor cable gland

Mechanic accessed the hydraulic lines indicated here, in this position

Mechanic was caught and crushed in pinch point here

The electrical lockout was carried out but not the mechanical lockout. A risk analysis was not carried out because the task was considered simple. The energy stored by the arm of the reclaimer in a high position while the employee was working on the boom incline control motor was not taken into account.

Pictures of the Stockbridge site (US A&C) above which illustrate the wheel loader crushing fatality linked to stored energy in hydraulic lines.

The bucket, which was initially extended to allow the mechanic to access the hydraulic lines, contracted and crushed the mechanic when the hydraulic lines were de-pressurized.