RMC-00-88 The UCISCO InSpecSM Furnace Tube Inspection Service An Innovative Inspection System

Description:

This paper describes a new inspection tool for use in furnace tubes similar to those found in fired heaters that process hydrocarbons. The primary components of a fired heater are a firebox and stack. The stack carries the combustion gases out of the fire box to the atmosphere and the firebox is a steel lined structure that contains the burners, a radiant section of tubes and a convection section of tubes. The burners ignite the fuel-air mixture to generate heat for processing the hydrocarbons passing though the tubes. The radiant section tubes line the inside wall of the firebox. To maximize the exposed surface area of the tubing and subsequent heating efficiency, the tubes are connected with tight radius 180-degree bends with a bend radius equal to one tube diameter. The convective section tubes are located at the top of the firebox just below the stack. The combustion gases pass over these tubes as they exit the firebox and enter the stack. To maximize heat transfer the convection tubes have extended surfaces attached to the outside of the tubing. The convection tubes are also connected with tight radius bends. However, an additional complication exists for conventional inspection because convection tubes are stacked, with three or more rows of tubes staggered one row on top of the other.