8 SURFACE MACHINERY AND METHODS FOR OIL-WELL PUMPING.
horsepower are desired. This type of boiler occupies little space,
gives large heating surface at less cost than the locomotive type, and
is simply built. However, the flues are liable to leak and the hotter
gases have a tendency to pass mostly through the upper tubes. A
common type of return tubular boiler sold by oil-well supply com-
panies has a dome, is of 40 to 70 horsepower, and is known as the
California type, from its wide use in the California fields. The re-
turn tubular boiler, without the brick and fittings, weighs about 25
per cent less than a locomotive boiler of the same horsepower rating.
Water-tube boilers include all types of boilers in which the water
is inside the tubes and the flames and gases from the fire are outside.
These boilers are much better suited than the locomotive or return
tubular types for central power-plant requirements. Although the
initial cost of water-tube boilers is comparatively high, the high
over-all efficiencies obtained warrant use at large power plants.
With the increased use of electric power for pumping oil wells, more
steam power plants generating from 200 to 1,200 horsepower are
being installed in some oil fields. Many such plants are in use in
the Gulf Coast oil fields of Texas and Louisiana.
If power units not greater than 250 horsepower are preferable at
these central power plants, return tubular boilers are used; if units
of higher capacity are desired, water-tube boilers are used. Such
plants generally run at uniform load 24 hours a day; they may have
periods of peak load during certain hours, but seldom or never have
periods of no load. Under these conditions, with the larger incidental
power requirements, the chief considerations are fuel and labor
costs, thermal efficiency, and safety and durability of plant. Opera-
tions are large enough to warrant the introduction of the usual boiler-
plant auxiliaries that are essential to efficiency. Small or temporary
boiler installations, however, may be run only a few hours a day,
using gas fuel, which if not used in the boiler would be wasted, and
employing men who are not regular steam engineers. Under such
conditions small boilers of the locomotive or return tubular type are
BOILER PARTS, FITTINGS, AND AUXILIARY EQUIPMENT.
For general information on boiler domes, steam drums, water
gages, steam or pressure gages, fusible or soft plugs, safety valves,
blow-offs, steam taps, condensers, feed-water heaters, and other
auxiliary equipment, the reader is referred to standard literature
on these subjects.2
2Am. Soc. Mech. Eng. Boiler Code; Kent's Mechanical engineer's pockjet book; Marks's
Mechanical engineer's handbook; or Peele's Mining engineer's handbook.
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 April 1, 2015.