Operational procedures

What are the general working instructions?

Water jetting techniques involves certain risks. It is preferable to choose working methods using ma­chines and attachments that do not require the presence of workers in the direct line of fire while performing a water jetting job.

In this regard, the following order of preference should be applied as a basic principle:

1. Fully automatic water jetting
2. Semi-automatic water jetting
3. Manual water jetting

Having selected the working method, considering the information above, it is important to take into consideration some aspects about how the water jetting team should be organised during the operation:

• The whole team must understand their role and must have received the specific instructions for the job before work commences.
• All water jetting operations should be controlled by a qualified supervisor.
• Generally, the water jetting team will consist of at least 2 or more workers according to the equipment used and the nature of the job. However, one-person operation is permissible in certain circumstances, depending on the pressure and flow.
• Team members should rotate their duties during any job to reduce fatigue if they have the competence to fulfil both positions as pump operator and jetter.
• The supervisor (or team leader) is responsible for basic checks of the equipment, of preparing the working area for the operation, and obtaining a work permit where and when required.
• Before starting an operation, the team members must agree on a code of signals to be used during the operation of the equipment
• Adequate PPEs, provided to the workers must always be used correctly during the operation
• The operators should be fully familiar with the equipment being used.
• The changing Water jetting equipment during operations, e.g., nozzle change, is only permissi­ble on deenergised systems with the high-pressure pump shut down.
• Every water jetting operation should include at least two ways of stopping the flow of hi­gh-pressure water.
• The emergency depressurisation and emergency stop protocol should be known by every worker of the water jetting team.

How should be managed the emergency stop?

An emergency depressurisation and emergency stop must be present on every water jetting system and working area, and before starting ay job, it must be inspected and tested for proper function.

When, during the operation, a dangerous situation arises, the emergency depressurisation must be activated immediately by a certified person who must be always in visual contact with the jetter. In case the visual contact between the jetter and the emergency stop and/or depressurisation operator is not possible a third person must be added to the team.

How should be the communication between workers during the operation?

Effective communication between members of the water jetting team during operations is extremely important to perform the work in a safe and efficient way.

The communication system that is going to be used during the execution of the work must be agreed by all of the members of the water jetting team before starting the operation. The supervisor must con­firm that every member of the team knows and fully understand the chosen communication system.

One extended way of communicating is by using hand signals, as noise levels during water jetting ope­rations and the nature of the protective equipment, e.g., hearing protective equipment, being used limit voice communication.

If hand signals are used, clear signals for each step in the operation of the equipment (start the pump, raise the pressure, lower the pressure, shut down the pump, etc.) shall be agreed by all workers. The supervisor is responsible for ensuring that each member of the team understands the meaning of each signal before the operation begins.

Hand signals being given by the jetter are only to be given when they have released the water gun triggers and depressurised the system as the jetter requires two hands to safely hold the device.

Moreover, in recent times, very effective radio-communications are being introduced in the market. Their use is not generalised yet, but it is being used more and more in water jobs.

What precautions should be taken when working in confined spaces?

Confined spaces such as tanks, hoppers, and boilers pose added risk for workers, on top of the specific risks water jetting work incur.

They may contain toxic gases; they may not contain enough oxygen; and the materials stored in confi­ned spaces pose specific hazards as well. Moreover, when working in a confined space, workers may be at risk of entrapment, engulfment, or being struck by large pieces of falling debris.

Before workers perform work in a confined space, the employer must prepare and implement a con­fined space entry programme, which includes training of workers. The identification, evaluation, and control of confined space hazards are often quite complex. For assistance in assessing the hazards and preparing a written confined space entry program, it is necessary to consult a qualified occupational health and safety professional.

However, some general measures to take in account when working in confined spaces are:

• If possible, perform the assigned task using automated equipment.
• Use appropriate respiratory protection when the risk assessment includes the potential for release or creation of hazardous air contaminants.
• A qualified safety worker always needs to be present during entry to activate the emergency protocols in case of an accident or incident within the confined space.
• Ideally the worker in the confined space will be monitored verbally and visibly to assist in any needed at a moment’s notice.
• Appropriate entry conditions need to be met to enable the worker to safely enter the confined area or exit as quick as possible if needed.
• Ensure that lighting is designed for use in wet applications and is powered by an electrical panel with appropriate ground fault circuit interrupters.

Warning signs in the immediate vicinity are set up to inform that a water jetting operation is in pro­gress inside the confined space and that they may not enter.

What precautions should be taking when working with hot water?

Water jetting operations with hot water (temperature above 70 °C) imply a lot of risks, added to the specific risks water jetting incur. Using hot water can cause hazards to personnel, to the surrounding objects and surfaces, to the water jetting system and to the environment.

To control these risks and to perform the job in a safe way it is important to take into account the following considerations:

• Ensure that the thermal insulation of the jetting tools is sufficient.
• Ensure that the Personal Protection Equipment supplied to the workers is suitable.
• Confirm that the hoses, materials and attachments can withstand the maximum working tem­peratures and pressures (refer to the information provided by manufacturers and certificates).
• Ensure that the discharge of the jetting water is done in a safe manner.

What precautions should be taken when working with additives?

If the water jetting job requires the use of additives, the water jetting system and all its attachments must be intended for this purpose.

When products are added to the fluid sprayed, the effects caused by their diffusion must be taken into account and the following measures should be implemented:

• It is necessary to be familiar with the technical data sheet of the product and the safety data sheet of the additive and to always keep them on site.
• The safety measures contained in the technical data sheet of the product and the safety data sheet of the additive must always be observed.
• The operator must be effectively protected against the characteristics of the products added.
• The diffusion of added products cannot constitute an unacceptable burden on the environment.
• Polluted water must be removed under the conditions imposed for protecting the environment.
• It must be considered that the addition of additives often increases the risk of static electricity.
• What precautions should be taken when working with explosion hazard (ATEX areas)?
• When work is performed in an ATEX area, the equipment, procedures and preventive measures must meet the regulatory requirements of the country or region where the job is taking place.
• However, as a rule the following considerations should be taken into account:
• The client should be consulted about the necessary steps required by the contracting company to fulfil extra specific safety measures.
• Extra safety measures which might be provided could be the setting up of a continuous gas/atmosphere measuring device.
• All vehicles must be registered before entering the site, defining whether they have combustion engines or electrically driven motors which have to be grounded appropriately before work commences.

Links

• Table of contents of health and safety in water jetting

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