Like competitive sports, many industrial cleaning tasks are team endeavors. That is especially true of waterblasting with high- or ultra-high-pressure equipment.
Pump operators, nozzle operators, and site supervisors need to function as a team to ensure that jobs proceed efficiently and safely. Useful recommendations can be found in Recommended Practices for the Use of Manually Operated High Pressure Water Jetting Equipment, published by the WaterJet Technol-ogy Association.
It is basic currency for staff to be trained in the equipment and fully familiar with the work site and work plan. Beyond that, the job’s execution takes teamwork, from setup of the work site to teardown when the work is done.
Capable oversight
Like a coach, the supervisor prepares the game plan and makes sure the team members follow it. The role includes making sure all crew members have the necessary personal protective gear. It also includes pre-planning the work itself, selecting the team members best qualified for the job, and instructing them in the hazards of the work area, the safety standards, and emergency aid procedures.
In addition, the supervisor works with the site owner to define the limits of the work area, post necessary safety signage, and erect barriers to keep unauthorized people out. It’s also the supervisor’s role to make sure crew members have carefully inspected all hoses, fittings, nozzles, air systems, and other equipment and have properly laid out the high-pressure hoses with adequate protection against damage from vehicles.
Getting down to work
In general, a two-person crew is required for jobs involving waterjet equipment with system pressure greater than 4,000 psi and with flow greater than 10 gpm.
A waterjet crew typically consists of a pump operator and a nozzle operator, but one or more other people may be needed, depending on the nature of the job and the work site layout. For example, the nozzle operator may need help handling a jetting gun if it is fitted with more than one jetting extension, or if the hose must be fed forward into the workpiece. If the pump is at some distance from the nozzle operator, a team member may need to monitor the jetting action and communicate between the two operators.
In a typical two-person crew, the nozzle operator handles the “business end” of the equipment and is responsible for carrying out the correct pre-operation and operational procedures. This person may also be responsible for ensuring thatnecessary permits, permissions and agreements are in place before work begins.
The pump operator monitors and controls the pressurizing pump throughout the job. This is important, because the pressure delivered to the system has profound effects on the nozzle operator. For example, a sudden change in pump pressure changes the reaction force on the nozzle operator and could cause him or her to lose balance.
Working as a team
The pump and nozzle operators must be able to communicate from the start of the job to the end, even if the noise of the equipment drowns out their voices.
The WJTA manual says the team members need to agree on a system of signals for each step of equipment operation: start the pump, raise the pressure, lower the pressure, shut down the pump. The supervisor must make sure each operator knows and understands the signals before work begins.
Before and after bringing the system up to pressure, the pump operator must examine the hose and the connections to the jetting gun or nozzle to detect any leaks.
The pump operator starts the pump only when so instructed by the nozzle operator. Before bringing the pump up to pressure, the pump operator must make sure the nozzle operator has the jet nozzle directed at or positioned inside the workpiece and has a secure stance.
The pump operator then slowly raises the system pressure, enabling the nozzle operator to adjust to the reaction force from the jet. Once the operating pressure is reached, the pump operator must not adjust it further unless the nozzle operator is aware. At shutdown, the pressure also must be reduced gradually.
Staying fresh
The pump operator also must watch the nozzle operator and others on the team, and lower pressure if any team member approaches a potentially hazardous position.
Because the reaction force on a jetting gun can tire the operator, workers should rotate jetting duty. The supervisor should set a schedule to ensure that nozzle operators switch at intervals to other less demanding tasks.
The tips listed here do not represent all the safety precautions or crew member and team functions required for safe waterblasting. Workers and supervisors should consult the WJTA manual, their own company practices, and OSHA regulations for details. A well-prepared and well-coached team can make waterblasting a highly productive and safe venture.
