Method for dispersing and removing sludge contained in a storage tank

A method for redispersing and removing hydrocarbon sludge deposited in a crude oil storage tank containing crude oil and said hydrocarbon sludge, said method comprising the steps of:

• mounting on said crude oil storage tank an access port including a gate valve, and an isolation barrel open to said gate valve at the front thereof and having an axially aligned first packing gland in the rear end thereof;
• and
• inserting a joint of concentric pipes through said first packing gland, said joint of pipes comprising an outer pipe open at a front end and, said joint of pipe further comprising an inter pipe extending through said outer pipe thereby forming an open annular region between said inner pipe and said outer pipe, said inner pipe having means to mount nozzles means at a front end, said inner pipe being freely movable in an longitudinal direction within said outer pipe;
• and
• mounting nozzle means at a front end of said inner pipe;
• and
• opening said gate valve to establish communication between the interior of said storage tank and the interior of said isolation barrel;
• and
• extending said concentric pipes through said packing gland, through said gate valve and into said crude oil storage tank whereby said outer pipe is movable within the interior of said storage tank;
• and
• connecting an outlet fitting to a rear end of said outer pipe, said outlet fitting allowing fluid flow, controlled by an outlet valve, there through from said open annular region, said outlet fitting having an axially aligned second packing gland through which said inner pipe extends;
• and
• fluidly interconnecting said inner pipe extending through said second packing gland to a source of pressurized flushing fluid;
• and
• fluidly interconnecting said outlet fitting to a waste disposal means;
• and
• forcing pressurized flushing fluid through said inner pipe, out said nozzle means at said front end of said inner pipe into the interior of said crude oil storage tank;
• and
• withdrawing hydrocarbon sludge intermixed with said flushing fluid from said outlet fitting which fluidly interconnects with the interior of said crude oil storage tank through said annular region and said open front end of said outer pipe;
• and
• manipulating said inner pipe and said outer pipe within said storage tank to redisperse and remove hydrocarbon sludge from said crude oil storage tank.