The Locomotive - Lighthouse Survival Blog

150 THE LOCOMOTIVE. [October,
means uncommon where brass and copper are used for blow-offs. In a nest of three
boilers, recently inspected by this company, all the blow-offs (which were copper) were
found to be in a condition precisely similar to that shown in Fig. 7. It is believed that
the loss of material from the outside of such pipes is due, to some extent at least, to the
grinding action of small particles of unconsumed solid matter that are carried along by
the draft, the action being analogous to that of a sand-blast. The objections to this
theory are, first, that in such a case one would naturally expect the wear to be most
rapid along the bottom of the pipe, where the particles strike it most directly ; the
fact being, however, that the pipe wastes away about equally, all around its circumfer-
ence. The second objection to the sand-blast theory is, that although, judging frorn
the general properties of the materials, one would expect iron pipes to wear away from
attrition even faster than brass ones, the fact is, that iron blow-off pipes exhibit the
phenomenon to a barely perceptible extent, if at all. We are therefore impelled to the
conclusion that the wasting away of the brass and copper pipes is to be attributed, to
some extent, to chemical action. It is not unlikely that some of the products distilled
off from the fire may act corrosively on copper and brass, while leaving iron compara-
tively unaffected. However this may be, the important thing to note is, that the phe-
nomenon occurs ; and hence, whatever its cause maybe, it is a source of danger to be
borne in mind and to be provided against. And the easiest way to provide against it
is to put in an iron blow-off pipe.
Inspectors' Report.
August, 1894.
During this month our inspectors made 7,325 inspection trips, visited 14,730 boilers,
inspected 6,309 both internally and externally, and subjected 656 to hydrostatic pressure.
The whole number of defects reported reached 10,757, of which 1,261 were considered
dangerous; 31 boilers were regarded unsafe for further tier use. Our
mary is given below :
Nature of Defects.
Cases of deposit of sediment,
Cases of incrustation and scale,
Cases of internal grooving, -
- - -
Cases of internal corrosion, - - - -
Cases of external corrosion,
- - - -
Broken and loose braces and stays, - - -
Settings defective, -
- - - -
Furnaces out of shape,
Fractured plates, -
Burned plates, - -
Blistered plates,
Cases of defective riveting, -
Defective heads,
-
__.---
Serious leakage around tube ends, -
Serious leakage at seams, -
Defective water-gauges, -
Defective blow-offs, - - - - -
Cases of deficiency of water,
Safety-valves overloaded, -
Safety-waives defective in construction,
Pressure-gauges defective, -
Boilers without pressure-gauges, -
Unclassified defects, -
Total, - ...
- - - -
10,757
- 1,261