If you're branching out into drain cleaning, here are some tips to keep you safe — and alive — as you head out on your first waterblasting job.
After 30 years in the business, Gary Toothe’s job is to train people in the correct way to use water under pressure for industrial cleaning. “Anybody can buy the equipment. The difference between a good and okay waterblasting company is the people and what they know,” says the training manager for Federal Signal’s Environmental Solutions Group.
Unlike vacuuming, which has many variables that affect the job, waterblasting is all about horsepower, pressure and flow.
“Given the horsepower of your unit, you’re going to get a given amount of pressure and a given amount of flow,” he says. “As pressure goes up, your flow has to go down.
"You maximize your effort through planning. If you understand your system, you can predict everything.”
Customers will usually specify the required pressure based on the yield strength of the material being cleaned. Lacking that, you have to look it up; 90/10 copper/nickel steel has a yield strength of 9,000 psi, for instance. Staying close to, but below, that pressure will let you clean effectively without damaging the pipe.
Toothe says most people forget to check the belt tension on their waterblasting equipment, which leads to the waste of horsepower, fuel and profits. “Belts are usually about a half to a third as tight as they should be,” he says. “Nobody ever thinks to tighten them.”
Every manufacturer will have a “distance deflection” setting for their belts, such as 5/16-inch deflection at 18 pounds of force. Mechanics can make that adjustment using a belt testing gauge. Operators should then test the tension manually before every job. “Open the access door and hit the belt with a wrench,” he explains. “If you get a good ring, go ahead. If you hear a thud, tension the belt.”
Another under-appreciated aspect is the length of hose/lance being used. Often, he says, people will just buy a 100-foot unit figuring that will handle any project they might do. “You pay a toll in pressure for every foot you go. If I try to move 2 gpm through a 1/16-inch hose or lance, I lose 680 psi for every 50 feet. If I try to move 8 gpm, I lose 10,864 psi.”
One customer of his made that mistake; using a 100-foot unit with a 10,000 psi pump for jobs that needed a 15-foot unit. “They lost 7,000 psi every time they turned on the pump,” he says. Even using a 25-foot lance would have been better, costing them only 1,700 psi. “Instead of blasting at 3,000 psi, they would be doing it with 8,300 psi, which is accomplishing a whole lot more than they were.”
Besides using the appropriate length, he says, preventing pressure drops is accomplished by paying attention to the formula — use a bigger lance first. If that is not an option, use less flow.
The kind of tip is determined by what you are trying to do. “If a line is plugged, you have to locate the plug, break through the plug and then clean the pipe so it doesn’t plug again. That’s three different jobs that may require three different pressures and three different tips.”
Tips are designed for one of four tasks by directing the water jet in specific directions:
- Breakthrough (all flow aimed forward)
- Polish and descale (sideways flow to remove debris from the pipe)
- Debris removal (flow at 45-degree angle to push debris backward)
- Forward thrust (flow at a 15-degree angle for forward movement of the lance)
Unplugging a pipe, for instance, will require a breakthrough tip combined with tips that provide forward thrust. Once you open the clog, the breakthrough tip should be removed — it’s not doing anything — and replaced with tips to remove and flush out debris.
“Sometimes two steps are better than one,” Toothe says. “If you have the right tip, it will fly through the job and then you can put on the other tip to finish it up. You get done a whole lot quicker.”
Appreciate the danger
Every job site has the usual workplace hazards. Waterblasting compounds the risks. At 10,000 psi, injuries can be fatal.
“This is a team sport,” he warns. “It can be very dangerous so you don’t do anything without someone having your back.”