Oxyacetylene torches and hand-held gouges are traditionally used to cut petroleum storage tanks for dismantling or repairing. The method is considered risky and time intensive, according to Mass Technology Corporation. The company introduced its Safe-Cut service, and obtained the rights to a cold-cutting process involving ultra-high pressure waterjets for use in the refinery industry.
Since 2007, Kilgore, Texas-based Safe-Cut has transformed the rehabilitation process of petroleum storage tanks, with a safer and more efficient cutting processes. Access to Water or electricity is not required for Safe-Cut's entirely self-contained mobile rig, which features a number of portable waterjet cutting systems.
This includes Jet Set Hydro Technics’ two RAGWORM® robotic waterjet cutting systems, specifically designed for removal of side-shells, roofs, and tank floors, and a Jet Edge portable Spyder waterjet cutting system, which can perform radius, circle, pipe and linear cutting. These systems are powered by three Jet Edg, diesel-powered, waterjet intensifier pumps, including a 55,000 psi, 260hp Jet Edge iP55-260DX pump, a 55,000 psi, 280hp Jet Edge iP55-280DS pump, and a 60,000 psi, 80hp Jet Edge iP60-80DS pump.
Safe-Cut's RAGWORM systems are capable of cutting floors with a thickness of more than 1 inch. Carbon steel of ¼" thickness can be cut at an average speed of 38 meters/hour (125 ft/hour) per cutter. This technique cuts materials at least five times faster than torches and 30 times faster than gouges. The Jet Edge Spyder system is capable of cutting 30 ft/hour and is a suitable cutting tool for vessels, steel reinforced concrete, pipelines, and fabricated metal structures. In both systems, ultra-high pressure water is propelled through a small orifice to create an abrasivejet capable of traveling faster than a bullet. This abrasivejet is capable of cutting through almost any material.
The company has witnessed rapid growth since the launch of mobile waterjet cutting services, with customer response being extremely positive. Jimmy Wolford, Safe-Cuts vice president, explained that the safety feature is a key selling point as industrial safety is a major concern in the refinery industry. Torches are risky as they not only produce fumes but also noxious gases, there is also a risk of fires or explosions. Waterjet cutting eliminates the risk of fire even when there is leakage in tanks with hot bottoms.
Wolford went on to say that the traditional techniques of cold cutting, such as hand-held waterjet cutters or air chisels are laborious. The Safe-Cut service is safer, cleaner, faster, and requires less manpower. Multiple layers of steel plates and fiberglass or epoxy liners can be cut in one pass using waterjets as they are more efficient. When using a torch it is necessary to blast away or delaminate the liners from the steel plates before cutting.
Advantage of Using Jet Edge Waterjet Systems
Customers are impressed with the efficiency and minimal water and garnet usage quality of the RAGWORM system. Safe-Cut, demonstrated their capability when approached by Eastman Chemical, who were initially skeptical. Safe-Cut were able to cut the bottom plate of a 52' diameter chemical tank into 6' X 20' sections, using only 800 lbs of garnet and 375 gallons of water, compared to three to four tons of garnet, 10,000 to 12,000 gallons of water, and a cutting time of four days as quoted by other companies.
In another project, Dow Chemical Company wanted to change an existing gauge pipe in an aboveground flammable naptha storage tank to obtain accurate product level measurements (Figure 1). To achieve this, a vertical slot 1½" wide by 24" high needed to be cut at the bottom of a 40' riser pipe suspended in the tank. Traditional methods would require the tankto be drained, cleaned and de-gassed prior to cutting the pipe. However Safe-Cut developed a specialized waterjet cutting tool that is lowered down within the riser to perform the cut. It took five hours to complete the job safely, without taking the tank out service. The ultra-high pressure water was created using Jet Edge's iP60-80DS intensifier pump.
Figure 1. In a project for Dow Chemical Company, Safe-Cut developed a special waterjet cutting tool that was dropped down a 40' riser into a tank full of 32' of flammable naphtha. (Photo courtesy Safe-Cut)
For DCP Midstream, LLC, based in Carthage, Texas, Safe-Cut destroyed three 35' diameter 32' high tanks using a 280hp Jet Edge iP55-280DS pump in a quick turnaround time (Figure 2). To help with the cleanout of the tanks, four entry points were cut in each tank using the Jet Edge Spyder. To lift and remove the tanks by crane, Safe-Cut cut six lift points in the top of each tank. The center support was remotely cut using the Spyder after the tanks had been drained, enabling the hooking of the waterjet cutter to the outer surface of the tank. This allowed Safe-Cut to cut and remove the top halves of each tank using a crane, and the demolition process was completed with shears. The use of the Jet Edge iP55-280DS pump allowed Safe-Cut to run two waterjet nozzles to complete the work rapidly.
Figure 2. Safe-Cut used its Jet Edge-powered portable waterjet cutting systems to demolish three 35' diameter, 32' high tanks. (Courtesy Safe-Cut)
Delek Refining, LTD of Tyler, Texas, approached Safe-Cut to remove a 30' long, 10' diameter horizontal vessel, located within a production unit (Figure 3). Since pipes and equipment were on all sides of the vessel, traditional cutting techniques were not advisable. The presence of ½" steel and 1" of refractory linings in the vessel created further challenges (Figure 4). With the Safe-Cut system, all of these substrates were cut at once by applying ultra-high pressure water using the Jet Edge iP55-280DS pump. The vessel was cut into 12 pieces and a specialized circle cutter was used to create two holes in each piece to allow lifting and removal by crane.
Figure 3. Safe-Cut cut apart and removed a 30' long, 10' diameter vessel from a production unit at Delek Refining, LTD in Tyler, Texas. The vessel was constructed of 1/2" steel and 1" of refractory material. (Courtesy Safe-Cut).
Figure 4. A sample of the tough steel and refractory material Safe-Cut cut with their waterjet circle cutter when cutting the lift points on the vessel.
This information has been sourced, reviewed and adapted from materials provided by Jet Edge, Inc.
For more information on this source, please visit Jet Edge, Inc.