PRIME MOVERS AND POWER PLANT MACHINERY.
Boilers are of two general classes: Fire tube, in which the gases
pass through tubes expanded into headers forming part of the
shell; and water tube, in which the water is in the tubes, the gases
passing around them. The locomotive and California types of
boilers, common in oil field use, belong to the former class.
Fire-tube boilers are either internally or externally fired; the
locomotive type, shown in Plate III, B, is an example of the former,
and the horizontal return tubular type shown in Plate III, C, of
the latter. Both types are sold by the oil-well supply companies.
They are generally installed first for drilling service and later used
LOCOMOTIVE TYPE OF BOILER.
The locomotive type of boiler was used almost exclusively in the
older oil fields and is still the more common, except in California.
It is made in sizes from 20 to 60 horsepower, and is built for a
working steam pressure of 100 to 125 pounds. This type of boiler
is good for small or temporary plants, as it is self-contained, easily
portable, and requires no external furnaces or setting and but little
space. To make them readily portable some types are being built
with permanent mountings, consisting of steel wheels and axles;
for those with detachable mountings, the wheels, axles, and saddles
are temporarily attached by means of chains or steel rods with
turnbuckles and U bolts. A 40-horsepower boiler of this type weighs
about 10,000 pounds without the mountings. This type of boiler
is cleaned and repaired with greater difficulty than the return
tubular or water-tube type.
With this type of boiler there is danger of defective circulation;
leaks often start from unequal expansion of boiler shell, tubes, and
fire box; and unsuspected corrosion may go on in parts that can not
be readily inspected. Often the operator through ignorance or in-
difference permits scale and mud to collect on the crown sheet or in the
water legs, or the water level to become too low; then overheating and
blistering or bagging result. An examination of the repair work
being done in the average field boiler shop will generally show
that the locomotive type of boiler has received more abuse in op-
eration than any other form of mechanical equipment used in the
HORIZONTAL RETURN TUBULAR BOILER.
Horizontal return tubular boilers are becoming more widely used
for drilling as well as for permanent pumping plants in many oil
fields where moderate steam pressure and capacities of less than 200
George, H. C. Surface Machinery and Methods for Oil-Well Pumping. Washington D.C.. UNT Digital Library. http://digital.library.unt.edu/ark:/67531/metadc12407/. Accessed August 28, 2014.