3.1 The results obtained by this test method can be used in combination with other test methods for the selection of a lining for surfaces in flue gas desulfurization (FGD) systems that will be exposed to hot unscrubbed flue gas or to scrubbed gas that has been reheated well above the water dew point.

3.1.1 This test method does not evaluate or correlate to areas within the scrubber or scrubbed gas streams at temperatures at or below the water dew point.

3.2 This test method is intended to evaluate the combined effects of heat and exposure to sulfuric acid upon a lining system as applied to a carbon steel substrate. It does not produce the thermal gradient through the lining that may exist in actual applications. Actual lining performance may also be affected by concurrent physical or mechanical effects and other chemicals that may be present in the flue gas.

3.3 This test method evaluates major failure modes of linings applied to square test panels that are cycled from room temperature to a designated elevated temperature.

3.4 The recommended test temperatures of 200°F (93°C) and 350°F (177°C) are based on typical maximum operating zone temperatures in flue gas desulfurizations systems. Other temperatures may be evaluated as desired. Cycling to lower temperatures, including freezing, may be considered if applicable.

3.5 The standard acid concentration for all tests is 20 %, recognizing that the concentration will quickly rise to the equilibrium at the selected test temperature.