In a boiler, the work - in this case, heat transfer - is carried out by the boiler tubes. The type of boiler (firetube, water tube, etc.) may affect the orientation and layout of the boiler, but the tubes are still transferring heat from the fire side to the water side. It is for this reason that boiler tube maintenance and repair are essential. As a result of the large temperature gradients, boiler tubes are subjected to a great deal of stress, so the tube design, material, and thickness have been chosen carefully for optimum and efficient operation. As boiler tubes may be the most crucial component of most boilers, the importance of proper operation, maintenance, and repair cannot be understated.
On board the ship, some of the common repairs made to the marine boiler are plugging of the tubes and replacing the leaky manhole joints. The dry dock must also be used for other major repairs, such as replacing damaged tubes and rebuilding the furnace. To fire the boiler, a temporary repair must be made to the leaky boiler tube. Regardless of the situation, and regardless of the condition, the boiler must run.
Boiler tube repair method A method for the fast and efficient repair of tubes in a furnace boiler water wall involves milling elongated slots at each end of a damaged tube section. This damaged tube section is then cut away and replaced with a new tube section having elongated slots milled at each end and which is cut to mate with existing tubes. In order to secure the replacement tube section, the existing tubes and the replacement tube section are aligned to form elongated slots through which interior welds are made. To complete the repair, the elongated slots are then closed with covers made from a second section of replacement tubing, and the water wall web is attached to the replacement tube section. In addition to the milling machine used to mill the elongated slots, drill and saw fixtures are also disclosed to assist in cutting away damaged tube sections.