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PART III.
CALCULATING THE WORKING PRESSURES FOR BOILER
SHELLS.
Board of Trade rules concerning the working pressure of the cylindrical
shell of a boiler
Examples in calculating the working pressure of boiler shells
Example 1. Steel plates, steel rivets; Double rivetted joints; Longitudinal
seams fitted with double butt straps; Circumferential seams lapped
Diagonal pitch of the rivets
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39
Rule for determining the collapsing pressure of a plain iron tube
43
Iron plane furnaces
44
Board of Trade rules in regard to their construction; Calculation of the
Formula for calculating the working pressure; Corrugated furnace, iron
50
Iron and steel plane furnaces; Corrugated steel furnaces; steel fire box
for donkey engine.
54
Plane and corrugated steel furnaces; Corrugated iron furnace
55
Flat surfaces, stayed; Board of Trade rules for calculating pressure on
Flat iron plate; Stayed steel plate
Square inches of support allowed to each stay; Pitch of the stay
Staying of flanged fat surfaces, illustrated.
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Calculations concerning the stays; Working pressure allowed to stays; Calculations for stays for flat surfaces
Working pressure of a solid steel stay; Tensional stress per cross sectional
square inch of stay; Cross sectional area of solid steel stay, etc.
Greatest amount of plate area which one steel stay may support; Solid iron
stay, and rule for finding working pressure
Strain on each square inch of cross section of stay
Girder stays for combustion chambers
Girder stay in position on top of a combustion chamber; Girder stays with
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EXPERIMENTS UPON THE STRENGTHS OF RIVETTED JOINTS
OF STAYED FLAT SURFACES, AND OF BOILER FURNACES.
.
Summary of the dimensions and of the ultimate stress per square inch of
metal left between the holes
Formula for calculating the percentage value of perforated compared with
the unperforated plates
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77
Summary of the difference between the actual and calculated percentage
strength of perforated plates
78
Summary of the calculated and actual strength of the lengthway perfor-
ated plates in terms per cent. of the solid plates
Summary of mean stress per square inch of net section between holes of
perforated plates
Summary of ultimate stress per square inch of net section of perforated
plates compared with unperforated plate
Summary of difference between the ultimate stress per square inch of net
section of perforated and unperforated plates
Summary of elongation of holes in perforated plates at ultimate stress
Summary of appearance of fractures of perforated plates
Summary of the reports respecting the results of testing rivetted joints by
pulling stress
Summary of ultimate stress per square inch of gross area at joint
Summary of comparison between actual and calculated percentage strength
of rivetted joints .
86
Summary of ultimate stress per square inch of net section between the
rivet holes
Summary of ultimate stress per square inch of net section between rivets
compared with solid plate
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8
Respecting experiments made to ascertain the tensile stress and ductility
of the rivets used in the rivetted joints .
Summaries of the tensile stress and ductility of the rivets used; Mean ultimate tensile and shearing stress of rivets per square inch .
Experiments upon tubes representing the furnaces of marine boilers.
Experimental tubes representing the plane furnaces of marine steam boilers,
illustrated
Experiments upon steel plates representing the flat surfaces of steam
boilers, illustrated .
Results of testing by hydraulic pressure a box made of inch steel plate.
The plate supported by stays 14 inches diameter, screwed through the
plate and rivetted over. Stays spaced 11 inches by 11 inches
Experiments on the flat surfaces of plates representing the combustion
chambers of steam boilers, illustrated
The plate supported by stays 13 inches diameter, screwed through the
plate, and rivetted over stays spaced 11
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inches by 11
Results of testing by hydraulic pressure a box made of
inches
inch steel plate.
98
plate and riveted over stays spaced 11 inches by 11
The plate supported by stays 1 inches diameter, screwed through the
plate and fitted with very thick nuts. Stays spaced 11
inches.
inches by 11%
100
Results of tests of steel boxes made of % and inch steel plates;
Stays 13 inches and 2 inches diameters; Pitched at 11% by 11 inches,
screwed through plates and having very thick nuts
Experiments under supervision of Thomas W. Traill, engineer, on the
elastic limit and the pressure at which a permanent set takes place, illus-
trated.
6
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103
PART V.
CALCULATIONS COMPLETE FOR A MODERN HIGH PRESSURE
MARINE BOILER.
Steel boilers; Diameter 12 feet 6 inches; Length 9 feet 9 inches; Work-
ing pressure 160 lbs., illustrated
Thickness of plating; Calculations for the shell
Calculation for the plate section at the 8 inch pitch; For the rivet section,
i. e., double shear of 23 rivets in one pitch of 4 inches
Calculation for the plate section at the narrow pitch added to one-half of
the double shear of the wide pitched rivet; For the strength of the
double butt straps through the line of narrow pitched (or inner row of)
The diagonal pitch of the rivets
The steam receiver illustrated and described
Formula for the plate percentage of cylindrical shell of the receiver
Rivet percentage of cylindrical shell; The end plates of the receiver
Stay of steam receiver
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109
110
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112
113
114
115
The stay tubes and tube plates illustrated and described
116
Calculations for the stay tubes, the front tube plate and the back tube
plate
The front tube piate; Calculation of its strength; The stay tube at the back end
Calculation for the amount of stress on each cross sectional square inch of
stay; Effective area of plate supported by stay; Lbs. on each square
inch of stay
119
The combustion chamber, or combustion box
Calculation for the back plates of the box.
Calculation for the side plates of the combustion chambers
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127
128
Calculation for the bottoms of the combustion boxes
The stays below the furnace, illustrated
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133
PART VI.
DRAFT OF A SPECIFICATION FOR A MARINE BOILER.
Notes on marine boiler construction
137
The stays; Table of full diameter, effective diameter, at bottom of thread,
of number of threads per inch
139
Shape of the stays that pass entirely through the steam space of the boiler,
140
Correct position of longitudinal seams, rivets and circumferential seams;
Position of stays when plane furnaces are used
Allowance for corrugated furnaces; Flanging; Tubes; Irons for the bend
on the smoke box; Plates for flat bottom, and for circular boilers;
Steam pipes from boiler to engine
146
147
Marine boiler fittings; Safety valve; Spring loaded safety valve, illustrated
and described
149
Steam gauge; Pipes for the water gauge
Position of the gauge glass; Test cocks
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151
Scum cock; Connection between the main boiler and the donkey engine;
Fittings for donkey engines
Valve and chest for feeding marine boilers with fresh water; Leakage of
the boiler from imperfect feed arrangements; Steam pipes
The feed water for marine boilers
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154
Examining marine boilers; Testing new boilers; Springing down of the
back tube plate by defectiveness of the girders, illustrated
Distortion of the combustion box by imperfect fitting of the gusset stays;
Collapsing of marine boilers, illustrated .
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156
Testing of old boilers by hydraulic pressure
157
Preparation of the boiler for inside and outside examination; Examination
of the boiler; Dangerous corrosion from chemical or galvanic action
Only reliable way of testing the thickness of a plate; Examination of the
flanges of the furnaces
Examination of the man-hole and man-hole door, of the outside surfaces of
the end plate, insides of the furnaces and combustion boxes, etc.
Leaky rivetted joints
Inefficiency of cauiking the bottom seams of a boiler; Leaks in combus-
tion boxes; In furnaces
Repairs of old boilers; Of corrugated furnaces, etc.
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