When Jim Hutzler started Yankee Fiber Control, Inc. in 1984, in East Providence , Rhode Island , he focused on asbestos abatement. In the late '80s, he “discovered” water while looking for a more efficient method to do the work. Says Hutzler , “We started using 10,000 psi and were pleased with the results. However, when we first saw ultra-high pressure water in the mid '90s, I was skeptical. My first reaction was that it was pretty good for the laboratory, but where else would there be an application?”
Slowly, his view has changed. When his company first diversified into lead removal, he typically used chemicals, sandblasting, or small hand or power tools. But , when he landed a contract with a large pharmaceutical company, he decided to try ultra-high pressure (UHP) jetting after another sandblasting company gave up trying to get rid of a primer coat on the project. Recalls Hutzler , “The project was a disaster. We subcontracted the job. Water would take everything off down to the primer, but the primer was incredibly tenacious. It was a pickled primer, which was difficult to get off even when we turned to grinding.”
Still, he didn't give up on the possibility of using UHP for future projects. About a year later and after the formation of a new division, Yankee Surface Technologies, Inc., he contracted to remove lead paint from structural steel on a clarifying tank at a wastewater plant. Once again he turned to water: “We went out and rented some equipment along with an operator. The job was successful; the whole operation went pretty smoothly . At that point, we decided to purchase equipment of our own.” He is quick to add that using UHP has required a long learning curve: “Ultra high needs a tremendous amount of finesse and operator input. The work takes highly skilled operators.”
Over the past several years, Yankee Surface has used UHP for surface preparation in swimming pools, ships, and buildings, and to cut up built-up epoxy floors (typically ¼ inch thick) that traditional methods such as shot blasting do not take up . The process has proven effective at taking up thick mastic off floors, and one of his greatest successes has been taking up heavy elastomeric and urethane coatings. “ Elastomeric is a resilient coating that will expand and contract with the moving surface,” explains Hutzler . “If one starts to sandblast it, the energy of the sandblast is absorbed into the material, so this method is very slow. UHP works well on elastomeric projects, such as one where we were involved in cutting up rubber linings in tanks and vats in a caustic environment.”
UHP Effectiveness and a Ferryboat
Over the last several years, Hutzler has cultivated a relationship with Cape Cod-based Steamship Authority. In 2002, the company decided to have 40,000 sq. ft. of lead-based paint and 30 years of built-up epoxy removed from the interior freight deck of its 225 ft. ferryboat, Nantucket , one of 11 ships the company uses to service the islands of Martha's Vineyard and Nantucket .
The specs for the job required WJ2 cleaning of the walls and ceiling, shot blasting for the floor, and then recoating of all surfaces. Note: As described in SSPC-SP 12/NACE No. 5 , “A WJ-2 surface shall be cleaned to a matte (dull, mottled) finish which, when viewed without magnification, is free of all visible oil, grease, dirt, and rust except for randomly dispersed stains of rust, tightly adherent thin coatings, and other tightly adherent foreign matter. The staining or tightly adherent matter is limited to a maximum of 5% of the surface.”
Waterjetting was the best choice for several reasons. Sandblasting would drive any surface contaminants into the steel. On a ferryboat, which is in service in salt water, this becomes a crucial issue; UHP water cleaned the surface substantially cleaner, with no visible and non-visible contamination. In addition, waterjetting allowed other work to continue on the ferry. “While we were working, the owner was rebuilding large locomotive diesels down in the engine room,” explains Hutzler . “Had we been using abrasive grit on the project, it would have been a real challenge to keep the dust from drifting down into the diesel area.”
He describes the process: “For the ceiling and walls, we went in with two pumps, a 100 hp and a 200 hp, and a robotic tool, an 18 inch diameter ‘lawnmower.' We had to take off epoxy that varied in thickness from 1/16 inch to 1/8 inch thick. Using 40,000 psi at 9 gpm, we were cleaning over 400 sq. ft. per hour. The robotic provided great flexibility. For this job, we spring-loaded it onto a manlift .”
The work area was put under negative pressure. In other words, the work area was ventilated since so much water vapor was generated. To capture the wastewater, the scuppers (deck drains) were sealed, and a diesel vacuum was attached to the robotic unit to collect the water into vacuum boxes. The water was then properly processed.
Shot blasting (a process using dry, recyclable steel shot) was specified for the freight decks because it was less expensive than waterjetting and worked well on a flat, horizontal surface . Hutzler notes that the only drawback to this process was that the surface was not as clean. Two 30-inch shot blast machines were used . Since the units were self-contained, the shot was collected and recycled. Yankee subcontracted the recoating.
As always, all proper safety procedures were followed . “Our guys are lead trained, but for this job they didn't need to wear respirators because there was very low lead exposure since there was no dust. Of course, we tested first, and the lead was below the OSHA PEL or permissible exposure level,” says Hutzler . When the company had to turn to mole nozzles for some overhead work, the workers wore Kevlar® protective clothing: “With the nozzle shooting out at a 90-degree angle, we were obviously concerned that if someone became careless and pointed the gun in the wrong direction, a limb could be cut off.”
The job was to be completed in four weeks. The problem: “We failed to realize the degree of difficulty with such severe winter conditions,” explains Hutzler . “We had run the machines through winters previously, and we might have a few days of 20-degree weather, but this winter we had five to six weeks of it. When it snowed two feet one day, everything was shut down for a few days before access to the boat could be plowed. It was so cold that the fuel congealed in the diesel heaters, which were located outside the ferry and ducted into the boat. The heat just shut down. Then power on the wharf went out one night. And with the extreme cold, we had to keep the water and diesel engines running 24 hours a day. We ended up working two shifts. We worked 20 hours a day but found that the water would freeze up during the four hours if we didn't keep it running. It is definitely the coldest winter in my memory, and it took its toll.”
Despite the rough spots, Hutzler is pleased with the process and the equipment's performance: “This was the first time that we had used the lawnmower. It was a tremendous learning experience for us. If you compare a 200 hp pump and two men with open guns operating at 40,000 psi versus the same pump with the robotic lawnmower, we were easily getting four times the production with this equipment. As Don Bailey, the gentleman who developed the robotic equipment, said, ‘ The machine ran like a scalded dog.'”
The above article was provided by Cleaner Times , Technical Journal for High Pressure Water Applications .
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