Type.
The boiler to be of the Horizontal Tubular type with all castings and mountings complete.
Dimensions.
Boiler 72 inches diameter and 18 feet long. Each boiler to contain 90 best lap welded tubes 31⁄2 inches diameter by 18 feet long, set in vertical and horizontal rows with a space between them vertically and horizontally of no less than one inch and one-quarter (11⁄4) except central vertical space, which is to be three inches (3). No tube to be nearer than two and one-half inches (21⁄2) to shell or boiler. Holes through heads to be neatly chamfered off. All tubes to be set by Dudgeon Expander and slightly flared at front end, turned over and beaded down at back end.
Quality and Thickness of Steel Plates.
Shell plates to be 1⁄2-inch thick of homogeneous steel of uniform quality having a tensile strength of not less than 65,000 lbs. Name of maker, brand and tensile strength to be plainly stamped on each plate.
Heads to be of same quality as plates of shell in all particulars 3⁄4-inch thick. Bottom of shell to be of one plate, and no plate to be less than 7 feet wide. Top of shell to be in three plates. All plates planed before rolling, and all joints fullered not caulked.
Flanges.
All flanges to be turned in a neat manner to an internal radius of not less than two inches (2) and to be clear of cracks, checks or flaws.