A worker was injured after using high-pressure water jetting equipment, according to a significant incident report by the Department of Mines and Petroleum.
The worker was in a confined space cleaning demister pads using a jetting gun, lance and pencil nozzle supplied by a water-jetting pump, with a torch taped to the end of the lance because of poor visibility due to the dispersion of water and particles from the cleaning process.
“The worker stood upright, holding the high-pressure water lance between his legs, with the lance facing down and at 90° to the demister pads. The jet of high-pressure water struck his protective
gum boot while cleaning the pads,” the report said.
“The force of the water was sufficient to pass through the lining of the boot and penetrate the worker’s foot, creating a high-pressure injection wound that entered and exited through the inner ball
of his foot.”
The operating pressure of the water jet greatly exceeded the pressure rating of the protective gum boot worn by the worker, and the DMP outlined this as a direct cause.
A contributory cause was noted as the doubled recommended reaction force, caused by the pressure setting and water flow rate used during cleaning, as well as the worker not wearing appropriate personal protective clothing and footwear capable of withstanding the force of the water jet was not worn.
The report also said the torch attached to the lance partially obscured the worker’s vision of the nozzle head and working area, and there was insufficient lighting for the work task and environment.
The DMP recommended the following actions in the report to help reduce the potential for injuries when using high pressure water jetting equipment.
Prior to any high-pressure water jetting operations, conduct a suitable risk assessment for the proposed work task. Consider the nozzle type, maximum operating pressure of the pump, type
of equipment and water flow rate to be used.
Calculate the reaction force using the high-pressure water jetting pump’s maximum pressure rating and nozzle charts supplied by the manufacturer.
Use the calculations to confirm that the reaction force when operating the jetting gun will be equal to or less than the maximum reaction force of 250 N or 25.5 kg, as specified in Safe Work
Australia’s Guide for managing risks from high-pressure water jetting.
Note: When a reaction force greater than 250 N or 25.5 kg is required to achieve acceptable results, use mechanical devices to control the nozzle (e.g. mechanised equipment or engineered structures designed to hold the excess reaction force in all planes).
Protective footwear and clothing
Workers should wear protective footwear complying with Australian Standard AS/NZS 2210.3 Occupational protective footwear – Specification for safety footwear.
Where there is a risk of injury, personal protective equipment (PPE) should include:
– a foot and lower leg guard or shield
– leg and body armour
– protective gloves, face shield and eye protection.
These should be made of materials capable of withstanding the direct force of the water jet.
Note: Always wear suitable PPE regardless of the other control measures in place.
Workers should wear waterproof protective clothing complying with:
AS/NZS ISO 6529 Protective clothing – Protection against chemicals – Determination of resistance of protective clothing materials to permeation by liquids and gases
AS/NZS 4503.2 Protective clothing – Protection against liquid chemicals – Test method: Determination of resistance to penetration by a jet of liquid (jet test)
AS/NZS 4503.3 Protective clothing – Protection against liquid chemicals – Test method: Determination of resistance to penetration by spray (spray test).
Workers and the environment
Workers operating high-pressure water equipment should direct the water jet away from their body at all times. There should be sufficient lighting provided to the working environment.
High-pressure injection injuries
High-pressure injection injuries are serious with the potential to threaten life and limb. The combination of irritant material and high pressure can lead to extensive inflammatory reaction,
vascular compression and local necrosis.
Note: The pressure required to penetrate the surface of skin is about 7×10 5 N/m2 or 100 psi