A pair of 95-foot dilbit (diluted bitumen) tanks, each with between 3 to 4 feet of heavy sludge, needed to be cleaned for a required regulatory inspection (API 653). The ensuing project provided us with the perfect opportunity to compare traditional cleaning methods and modern robotic tank cleaning.
Each of the tanks began with 4-foot sludge bottoms. The client asked that RJ Maclean complete the first tank following traditional tank cleaning methods. For the second tank, the hazards associated with manned entry — due to the volume of sludge and intensity of cleaning — was a significant client concern. At the request of the client, RJ Maclean developed a methodology to reduce the duration and intensity of entries into the second tank.
RJ Maclean performed a series of “cold taps” on the tank’s manway flanges to allow access for circulation equipment. The company then employed its SandPiper Circulation System to suspend the sludge bottoms as a pumpable slurry, using boiler feed water as a diluent and circulation media. Finally, the tank was degassed with a temporary vapor recovery unit (VRU) and robotic manway cannon chemistry injection to prep it for manned cleaning.
The cleaning duration and intensity of manned-entry was reduced by 72 percent, with high-risk manned entry experiencing a reduction of 94 percent. The project was completed on time and on budget, with a 30 percent reduction in overall cost and duration.