Specification for 125 Horse Power Boiler
For one Horizontal Tubular Boiler 72 inches diameter 18 feet long for…………………of………
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.
Riveting.
Boilers to be riveted with 3⁄4-inch rivet throughout. All girth seams to be double riveted. All horizontal seams to be double riveted. Rivet holes to be punched or drilled so as to come fair in construction. No drift pins to be used in construction of the boilers.
Braces.
All braces to be of the crowfoot pattern, one and one eighth (11⁄8) inch diameter and the shortest to be no less than four feet (4) long and of sufficient number for thorough bracing, and to bear uniform tension.
Manholes, Hand Holes and Thimbles.
One manhole in top of each boiler with heavy cast iron frame riveted on middle of centre plate; one manhole near the bottom of each front head; head reinforced with a wrought iron ring two inches (2) square, riveted to heads with flush countersunk rivets two inches (2) pitch and to have all the necessary bolts, plates, guards and gaskets; two six-inch thimbles riveted to top of each boiler, each to have a planed face; one heavy 6-inch flange on bottom of each boiler, 12 inches from back end to centre of flange. There must be two braces, one on each side of manhole in front head; also to have three braces opposite manhole on back head below tubes.
Lugs.
Four (4) lugs riveted on each side of boilers, of good and sufficient size, with six one-inch rivets in each lug.
Castings.
Each boiler to have a complete set of castings consisting of ornamental flush fronts containing tube, fire and ash-pit doors, and provide the best stationary grate bars as may be selected by buyer, with the necessary fixtures, all bearing bars, britching plates, dead plates, binder bars, back cleaning out doors with frames. Anchor bolts and buck stays. The fire door to contain adjustable air opening and to be protected with fire shields. One heavy cast iron arch over each boiler.
Testing.
Boilers to be tested with a water pressure of 200 lbs. per square inch and certificate of such test having been made shall be furnished with boiler. Test of boiler to be under direction of such steam boiler Insurance Company as may be selected by buyer.
Quality and Workmanship.
All boilers to be made in the best workmanlike manner and all material of their respective kinds to be of the best, and in strict accordance with specification.
Fittings and Mountings.
The boiler to be furnished with the following: One four inch heavy mounted safety valve. One six inch flanged globe valve. Two two inch best globe valves. Two two inch check valves. One eight inch dial nickel plated steam gauge. One low water alarm gauge. One set of fire irons for two boilers consisting of hoe, poker, slice bar and shovel.
Drawings.
All drawings furnished for masons in setting the boilers.
Duty of Boiler.
The boiler to develop 120 horse power and to work under a constant pressure varying from 125 to 150 lbs. to the square inch.
All rivets are to be 21⁄2 and 11⁄2 inch pitch. The pitch line of the rivets to be not nearer 11⁄8 inches to the edge of the sheet.
To be 8 lug plates for each boiler not less than 2 feet long, 8 inches wide, and one inch thick.
There shall be six 1 inch anchor rods running front to rear of each boiler, in the brick work.
These boilers and all their fronts, fittings and connections will be subject to the inspection of…………………
Marks on Boiler Plates
Something has been said under another heading of the nature and requisite quality of the materials entering into the structure of the boiler. Too much emphasis cannot be laid upon the necessity for the use of the very best iron and steel that can be manufactured, and the most skillful and thorough workmanship that can be performed in constructing the boiler.
It is becoming the practice, both for land and marine boilers, for boiler plate makers to furnish “test pieces” from each sheet or plate that goes into the construction of a boiler, and a sheet showing the tensile strength of each sheet or plate that enters into its make up.
But irrespective of this practice each plate entering into boiler construction will be found to have one of the following marks, which designate its quality and method of manufacture. The name “Charcoal Iron” is used because in its manufacture wood charcoal is employed instead of mineral fuel.
“Charcoal No. 1 Iron” (C. No. 1) is made entirely of charcoal iron. It has a tenacity of 40,000 pounds per square inch in the direction of the fibre. It is hard, but not very ductile, and should never be used for flanging.
“Charcoal Hammered No. 1 Shell Iron” (C. H. No. 1 S.), although not necessarily hammered, has been worked up before it is rolled into plates. It has a tenacity of 50,000 to 55,000 pounds per square inch in the direction of the fibre. It is rather hard iron, and should not be flanged. It is used for the outside shell of boilers.
“Flange Iron” (C. H. No. 1 F.), is a ductile material which can be flanged in every direction. It has a tenacity of 50,000 to 55,000 pounds per square inch along the fibre.
“Fire Box Iron” (C. H. No. 1 F. B.), is a harder quality, designed especially to withstand the destructive effect of the impinging flame, and is used for boxes and flue-sheets.
The letters in the brackets exhibit the plate stamp.
Cast iron and copper were used in an early day for steam boilers and the former is still extensively used for certain forms of low pressure steam heaters made for various purposes, such as green houses, etc.