OUTLINE FOR DESIGN OF MACHINERY FOUNDATIONS

(1) General Considerations affecting Type of Foundation

(a) Soil: bearing-power, ease of excavation.

(b) Suitability of materials proposed as affected by workmen and machinery available; first cost; transportation facilities; permanency; influence of adjoining work; future work.

(2) Types of Foundations

(a) Timber blocking.

(b) Masonry: brick, stone, capstone.

(c) Concrete: plain, reinforced.

(d) Combination concrete and masonry.

(e) Piling: wood, concrete, pipe and concrete.

(3) Calculations and Design

(a) In general, design will be governed by experience and judgment.

(b) Depth of Foundation; fixed by bearing obtainable, and by required weight of foundation.

(c) Area of base; fixed by safe load on soil, and by required "spread" for stability. (d) Weight of base; dependent on character of machinery.

(e) Spread footing-course.

(f) Sand "cushion" footings to prevent vibration.

(g) Special foundations; steam-hammer, etc.

(4) Details

(a) Anchor-bolts to be free at tops; set right height; to be entirely removable on large work, with tunnels and hand-holes to bottom washers.

(b) Provide all required pits and tunnels, and give access to same.

(c) Provide drains from all pits and tunnels.

(d) Provide openings for all exhaust-pipes, elbows, etc.

(e) Provide ledges for floors; avoid "tripping steps" at dangerous places.

(f) Allow for grouting, and word drawing so that there can be no mistake as to final height of machine.

(g) Provide wood "dead-men" between bed-plate and masonry for machinery subject to shock.

(5) The Drawing

(a) Main and detail dimensions to be correct, and complete; tie up with existing work.

(b) Dimensions of foundation; location and height of anchor-bolst.

(c) Adjoining work; interferences.

(d) Notes, see (6).

(6) Specifications (or Notes)

(a) Foundations to go down to good bearing "as engineer in field may direct"

or otherwise.

(b) Kind and Quality of masonry.

(c) Proportions of Concrete, and Grout.

(d) Quantity of materials required.

OUTLINE FOR SMALL TANK DESIGNS

Note. This outline is intended to cover the design of miscellaneous tanks inside a factory, etc. For larger and elevated tanks, see outlines on pp. 64 and 65 respectively.

(1) General Considerations

(a) Best shape and size of tank for use intended or for future requirements: cylindrical, rectangular, conical bottom, hemispherical bottom, suspended, etc. (b) Influence of material to be confined on shape and materials of construction; acids, alkalis, etc.

(c) Adaptability for cleaning; are internal braces allowable?

(d) Adaptability for ease of repair.

(e) Adaptability for future extension.

(f) Staging: height, design, future extension, other loads.

(2) Size

(a) Capacity for use intended or for future requirements.

(b) Width, length and depth to go in space available.

(c) Proper depth for special requirements (constant head, etc.).

(d) Clearances required in shipment, whether shipped "knocked down" or "riveted up."

(3) Material

(a) Shell: steel, iron, C. I., galvanized steel or iron, copper, lead, wood, etc. (b) Bracing: rim angles; stiffening angles on top, sides and bottom; internal bracing, rods, flats, angles, etc.; gusset plates.

(c) Fittings: supporting lugs, angles, hangers, etc.; rivets; entrance, discharge and overflow connections; sumps; gratings and screens; gauge-glasses; man- and hand-hole covers; other fittings.

(d) Staging: structural steel, wood.

(4) Strength

(a) Shell: thickness of metal for sides, bottom, partitions and cover; unsupported surfaces. Efficiencies of joints. Spacing of supporting beams in relation to thickness of bottom.

(b) Bracing: rim angles; stiffening angles on sides, bottom and top; internal bracing, rods, flats, angles, etc.; horizontal circular girders (for conical-bottom tanks); gusset plates (for flat heads).

(c) Fittings: supporting lugs, angles, hangers, etc.; reinforcing plates.

(d) Riveting: size of rivets, type of joint, pitch, lap, etc.; countersunk rivets on inside or outside?

(e) Staging; for present and future loads.

(5) Details

(a) Openings: supply; discharge; overflow; sumps; washout; manholes; handholes; valves; screens.

(b) Partitions: location; height; openings in.

(c) Machinery, for stirring, etc.; attachments to tank; clearances for, etc.; see p. 80.

(d) Miscellaneous Fittings: gauge-glasses; thermometers; tell-tale; ladders, inside and outside; hatch covers in top; "blow-up" piping.

(6) Check drawing for

(a) Correct placing of views.

(b) Sufficient views.

(c) Sufficient detail.

(d) See if drawing may not have to be done all over again.

(e) Correctness of notes and titles.

(f) Completeness of notes and titles.

(g) Agreement with specifications.

(h) Schedule of orders; number of items required, and marks.

OUTLINE FOR DESIGN OF A LARGE STEEL TANK

Intended to cover design of large steel tanks for storing oil, water, molasses, etc.; resting on the ground (on concrete surface).

(1) Size

(a) Reduce capacity in gallons to cubic feet, after ascertaining whether U. S. or Imperial gallons are specified.

(b) Proportion diameter and height to obtain most economical (HD = 1:1 for 20 ft. diameter; 1/2 : 1 for 75 ft. diameter, about.) (c) Diameter and height in relation to space available for tank.

(2) General Arrangement

tank.

(a) Roof to be self-supporting (dished to radius equal to diameter), supported on trusses, on trusses with one central column, or on rafters with concentric rows of columns; black or galvanized sheets.

(b) Material of roof posts; structural shapes, pipe (plain, galvanized, or filled with concrete).

(c) Roof plates to be sectors.

(d) Bottom plates to be rectangular.

(e) Shell plates to be in courses 3/4/5 ft. high.

(3) Strength

(a) Bottom: empirically fixed at from 3/16 in. to 1/2 in. depending on size and character of job, usually 1/4 to 3/8 in.; size and rivets, joint (S. L. R.), pitch, lap.

(b) Shell: weight of liquid per cubic foot, stress per lineal inch at bottom of each course, efficiency of joint, allowable stress per square inch on net section, required thickness of metal; additional thickness to take care of rust or corrosion; top courses not less than (3/16 in.) thick; design of joint for required efficiency, size of rivets, style of seam, pitch, lap, etc., or simply state required efficiency and check contractor's design of joint.

(c) Roof: dished top plates proportionate to diameter (from 1/8 in. for 30 ft. to 1/4 in. for 75 ft. diameter); supported roof plates should support weight of a man on chosen span (usually No. 10); trusses and rafters figured for load of (—) lb. per square foot; minimum thickness of truss-material to resist corrosion.

(d) Angle Rims: top angle to resist distortion, proportionate to size of tank; bottom angle (or angles) proportionate to material of bottom and sides, rivets to carry weight of steel sides, bearing area for safe load on concrete.

(4) Details

(a) Ladder inside and out.

(b) Tell-tale: float, chain, wheels, indicator, scale.

(c) Inlet nozzle: caulking strip, size and drilling of flange.

(d) Discharge nozzle: caulking strip, size and drilling of flange, screen over on inside.

(e) Overflow.

(f) Manholes: in roof and shell, reinforcing for latter.

(g) Blowout pipes in bottom connected to a single blow-off valve.

(h) Vent in roof: finial.

(5) Check Drawing for

(a) Correct placing of views, especially of location of all openings in plan. (b) Sufficient views.

(c) Sufficient detail.

(d) Correctness and completeness as per above schedule. (e) Correctness and completeness of notes and titles.

(f) Agreement with specifications.

(g) Number of units required, and marks.

OUTLINE FOR DESIGN OF AN ELEVATED STEEL TANK

(1) Style and General Arrangement

(a) Hemispherical-bottom tank with columns attached to shell plates.

(b) Conical or segmental bottom tank with horizontal circular girder at joint; load taken to columns by brackets on shell plates, or on extension of latter down below joint.

(c) Flat-bottomed tank resting on steel beams; load taken to columns by girders under.

(d) Style of Roof: plates dished to radius equal to diameter of tank; conical or pyramidal shape, carried on rafters or trusses; pagoda shaped; of wood; finial. (e) Style of Tower: four, six, eight, etc., posts; consider use of four posts with two braces at top of each, giving twelve points of support; economy of small number; bracing of angles or of adjustable rods; choice of column section. (f) Platform at bottom of tank; horizontal girder (of conical-bottom ́tanks) usually designed for this purpose.

(2) Principal Dimensions

(a) Tank: reduce capacity in gallons to cubic feet after ascertaining whether U. S. or Imperial gallons are specified; proportion diameter and height for economy, appearance and ease of fabrication (details).

(b) Tower: height from bottom of steel of column to bottom point of tank; columns battered or vertical; spread at base and space available for same. (3) Strength

(a) Live Load: weight of liquid per cubic foot, stress per lineal inch at bottom of each course.

(b) Hemispherical Bottom: stress per lineal inch, efficiency of joint (usually S.L.R.); thickness required for stress, and for practical construction (not less than No. 10); sizes of rivets, pitch and lap; thrust of inclined posts to be resisted by a horizontal girder (single angle for small tanks.)

(c) Conical or Segmental Bottom: stress per lineal inch for circumferential and for longitudinal joints; efficiency of joint; thickness required for stress, and for practical construction (not less than No. 10); size of rivets. pitch and lap; horizontal girder, compression in due to load, moment in due to thrust of inclined posts.

=

(d) Flat Bottom: thickness as determined by load and spacing of beams (B. M. WL2/15); efficiency of joint, size of rivets, pitch and lap; additional thickness for rust.

(g) Tower.-Dead, live and wind loads; allowable unit stresses for each; max. 1/r for columns and struts; rivet values; horizontal bracing; size of base-plates, anchor-bolts.

(4) Details

See p. 64 (4-a to h.)

(i) Inlet Pipe.-Stuffing-box (to take care of movement), base elbow or tee, valve, lagging (for protection from frost).

(j) Platform.-Brackets, floor, railing.

(k) Swinging Discharge Spout (for Locomotive Supply Tanks).—Spout, counterbalance, discharge-pipe, valve, handle, supports.

(5) Check Drawing for

See p. 64 (5).

OUTLINE FOR PIPING DESIGNS AND DRAWINGS

Note. This outline is intended for use in connection with installations of steam, exhaust, boiler-feed, juice and similar piping.

It is supposed that complete "plan and elevation drawings," to scale, will be made by the engineers, giving center-to-center and other principal dimensions, but omitting detail figures dependent on the dimensions of the fittings, which are left to the pipe contractor. Furthermore, it is supposed that the material is ordered from a detail list and accompanying specification such as is illustrated on pp. 122 and 124, and that few or no general notes are placed on the drawing, but are covered by the specifications.

The first six sections are for the use of the engineer in preparing the preliminary single-line drawing and the notes to be submitted to the draftsman; the last section is intended to aid the draftsman and checker in producing the finished design drawing.

(1) General Arangement

The conditions governing the system to be adopted for steam, exhaust, boiler-feed, blow-off, vacuum, oil-supply, drip, juice, etc., piping are so multitudinous that no attempt will be made to cover them in detail. A few general

principles, only, will be enumerated, which apply, more or less, to all lay-outs. (a) Lay out so that repairs can be made without interfering with the regular service of the plant, i.e., on a system that will avoid shut-downs, or repairmaking at night.

(b) The system to be suited to the required continuity of service and hours per day the plant is in operation; i.e., bear in mind the proportionate seriousness of a shut-down, and put in a system that will either avoid it entirely or restrict in to a few hours duration, as the conditions may warrant.

(c) Bear in mind the principle that, in steam plants, more particularly, the choice of size of units and the choice of piping arrangements should be concurrent operations; the mere connection, by piping, of arbitrarily fixed units, is not "engineering."

(d) Typical Piping Systems

I. A straight-line header connecting a row of boilers and a row of engines. Cheap but very poor; repairs to the main involve a complete shut-down of the plant.

II. The "Double Main" system, involving a duplication of the piping of
No. I.

III. The "Loop" system; which may be briefly described as a connection of
the ends of the single header of No. I.

IV. The "Division" system; e.g., a row of engines opposite a row of boilers, each connected to a steam header running between and parallel to them; by choice of size of units suitable to class of load, portions of main may be shut off for repairs at times of light load.