Systems and methods for treating metal pipe couplings, including a frame and insulated panels attached to the frame forming an oven. A pre-heat zone and a bake zone inside the oven, the pre-heat zone separated from the bake zone by a shared oven wall. A combustion burner and recirculation blower are positioned in opposite ends of the oven in a pre-heat zone combustion/recirculation chamber. Another burner and recirculation blower pair are positioned in opposite ends of the oven in a bake zone combustion/recirculation chamber. Heated air supply plenums are fluidly connected to respective recirculation blowers, and include direction-adjustable nozzles to direct heated air generally downward onto pipe couplings moving through the preheat and bake zones. Return air plenums positioned in each of the pre-heat and bake zones each have an air inlet, and an outlet fluidly connected to respective combustion/recirculation chambers. Coating-cured metal pipe couplings made by the methods.