It is essential that good contact between the tubes and the fins is achieved, or the fins will be inefficient. This is achieved by welding to the tube or pressing fins onto the tube with a tight – fitting extended inner lip. Galvanizing the tubes plus fins after attaching them to the tubes can help ensure good contact. The water pipes should be kept short enough so that the force of the massecuite does not cause them to bend. The fins are generally square, with a side dimension between 120 and 240 mm, made of 3 ro5mm thick steel. Fin pitch varies between 19 and 50 mm. larger fins and pitches are sometimes found in the cooler part of the reheater, and smaller, closer packed fins in the warmer regions.