MARINE A horizontal boiler of the return tubular type. They are of many different types. and vary in their arrangement to suit different conditions.
An opening in the lower part of a boiler through which the sediment deposited by the water is removed. When the boiler is being used, the mudhole is closed by a door called the mud-lid which is inserted within the hole and pulled up against its inner face by means of a bolt. This bolt is attached to the door and passed through a bridge which spans the hole and rests against its outer face. The bolt is tightened to the bridge by means of an ordinary nut.
Muurtrtniotag BOILER.-- A boiler comp used of numerous tubes, through which the hot gases pass from the fire-box to the chimney, and thus heat the water which is in contact with the outer surfaces of the tubes. The locomotive, horizontal and The boilers are of this type.
The overheating of boiler parts is due either to incrustation, or to an insuffi cient supply of water.
It tends to soften the plates so that they bulge or fracture under the force of internal pressures.
The pressure developed in a steam boiler exceeding that which it is designed to sustain.
A plate, made properly of steel, riveted or bolted to boiler plates, which have been injured by accident, or have become weakened by corrosion.
Prrrn40.— The corrosion of boiler plates in patches. See Honeycombing.
In the manufacture of steam boilers the use of wrought-iron plates has been comple tely abandoned for those of steel. The steel plates are rolled in larger sins, thus reducing the number of riveted seams, and as they possess a much greater tensile strength, they permit of the development of the higher pressures required by modern engines.