Cast-iron Vertical Header
The vertical cast-iron headers have elliptical handholes with raised seats milled to a true plane. These are closed on the outside by cast-iron caps milled true, held in position by forged-steel safety clamps, which close the openings from the inside and which are secured by ball-headed bolts to assure proper alignment. All joints are made tight, metal to metal, without packing of any kind.
The mud drum to which the sections are attached at the lower end of the rear headers, is a forged-steel box 7¼ inches square, and of such length as to be connected to all headers by means of wrought nipples expanded into counterbored seats. The mud drum is furnished with handholes for cleaning, these being closed from the inside by forged-steel plates with studs, and secured on a faced seat in the mud drum by forged-steel binders and nuts. The joints between the plates and the drum are made with thin gaskets. The mud drum is tapped for blow-off connection.
All connections between drums and sections and between sections and mud drum are of hot finished seamless open-hearth steel tubes of No. 9 B. W. G.
Boilers of the longitudinal drum type are suspended front and rear from wrought-steel supporting frames entirely independent of the brickwork. This allows for [Pg 52]
[Pg 53] expansion and contraction of the pressure parts without straining either the boiler or the brickwork, and also allows of brickwork repair or renewal without in any way disturbing the boiler or its connections.
Babcock & Wilcox Wrought-steel Vertical Header Cross Drum Boiler
CROSS DRUM CONSTRUCTION—The cross drum type of boilers differs from the longitudinal only in drum construction and method of support. The drum in this type is placed transversely across the rear of the boiler and is connected to the sections by means of circulating tubes expanded into bored seats.
The drums for all pressures are of two sheets of sufficient thickness to give the required factor of safety. The longitudinal seams are double riveted butt strapped, the straps being bent to the proper radius in an hydraulic press. The circulating tubes are expanded into the drums at the seams, the butt straps serving as tube seats.
The drumheads, drum fittings and features of riveting are the same in the cross drum as in the longitudinal types. The sections and mud drum are also the same for the two types.
Cross drum boilers are supported at the rear on the mud drum which rests on cast-iron foundation plates. They are suspended at the front from a wrought-iron supporting frame, each section being suspended independently from the cross members by hook suspension bolts. This method of support is such as to allow for expansion and contraction without straining either the boiler or the brickwork and permits of repair or renewal of the latter without in any way disturbing the boiler or its connections.
