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Indirect Fired Heaters (Line Heaters)

Indirect fired heaters utilize indirect heating to efficiently transfer energy to the process media. These heater designs are also know as line heaters due to their decades long use at wellheads upstream of oil and gas production pipelines. Temperature ranges for the process media and bath fluid are typically lower than those used in other heaters.

The burner fires into a submerged fire-tube located in the lower portion of the bath heater shell. Energy is transferred from the fire-tube wall to the surrounding bath fluid. The bath fluid transfers the energy by natural convection into a series of process coils located in the upper portion of the heater shell.


Indirect fired heater shells are typically atmospheric, with an expansion tank located on top to compensate for the change in bath fluid density with varying bath temperatures. Process bath heaters have few moving parts, require very little maintenance, and can achieve efficiencies of 70% without the use of an economizer.

Indirect fired heaters designed for hazardous area classifications and control system components meet CSA, NFPA and UL recommendations.

Forced Draft and Natural Draft Designs

Petro-Tech offers both forced draft and convectional natural draft indirect fired heater designs ranging from 1.0 – 10 MMBTUH/Hr.

The process coil selection takes into consideration design requirements for inlet/outlet temperatures and maximum allowable pressure drop by controlling the number of passes, tube lengths, and tube size. The coil is built in accordance with ASME Section VIII, Div 1, ANSI B31.3 or B31.1 piping requirements.

Heat. Engineered with Passion.