element will be progressively higher each circulation until a temperature is reached in which the heat losses thru the insulation will equal the heat input and so a form of steady state will be achieved resilient flap type seals 40 are placed around the perimeter of the circulation chamber 30 to restrict the mixture of the seawater 42 within the circulation chamber with the seawater 44 outside the circulation chamber most conventional rovs have a minimum of 100 horsepower of electricity which can almost all be converted into heat thru a resistance heater so it can be readily seen that if the same seawater is circulated with only minimal leakage it can be quickly brought to a high temperature referring now to fig2 the apparatus of fig1 is shown below an rov 50 and operating in an area of the subsea pipeline 10 which has been uncovered in a ditch form 52 by uncovering only the top portion of the pipeline the lower portion of the seafloor is left intact to support the pipeline the thermal operating module is generally referred to as 55 referring now to fig3 an alternate section through the thermal operating module 55 showing rollers 60 and 61 mounted on motors 62 and 63 and pivoted about pin 64 cylinders 66 and 67 will move to push the rollers 60 and 61 against the pipeline 10 and the motors 62 and 63 will turn the.