flexible band such as a steel band through a collar portion such as 6a while applying tightening force and crimping the collar portion to hold the bands in place are commercially available for example a suitable system comprises the signode air binder model pnsc34 and other suitable systems are available from reda or centrilift pump corporations fig2 shows the lower end of a heater installation as shown the bottom end of casing 2 has been closed with a fluid tight cap 20 the weight supporting wireline 16 has been previously drawn by sinker bar 18 to near the bottom of the pipestring 2 end connection 19 of a pair of electrical heating cables such as those forming a lowermost heater are banded to wireline 16 by a band 6 a nearby end junction of a thermocouple 12 is similarly banded to the wireline where a very high temperature is provided by the lowermost heater a relatively cool zone is preferably maintained above the heater by a steel sheathed mineral insulated cable having an outer diameter similar to that of the heater cable but a current conducting core which is large enough to supply power to the heater without generating a high temperature as.