By the early to mid 1930's steam generated power for cable tool drilling rigs throughout Texas and elsewhere was giving way to the combustion engine and rotary tables. In the photograph above, from the Basil Clemmons Collection at the University of Texas at Arlington, old discarded boilers lie along side railroad tracks near Fort Worth waiting to be cut up for scrap metal.
The belly of these boilers contained a series of stacked tubes (flues) that displaced heat from the firebox and superheat the water in the vessel into steam. The fire box was generally stoked with wood, coal or natural gas. The vessel itself had a working pressure capability of about 100 PSI; the stream was bled off the top and then transferred to steam driven engines like the one below.
Those engines turned big band wheels that moved Pitman arms around and around and walking beams up and down.
Here is another photograph belonging to the Basil Clemmons Collection of the guts of a steam boiler being salvaged. The more tubes (flues) and the longer those tubes, the more steam generated horsepower the boiler was capable of, some up to 125 HP.
If the water used to general steam was slightly mineralized, or had high total dissolved solids, those tubes had be constantly wire brushed to keep them open and clean.
Boilers would blow up occasionally split a seam, or blow out rivets, but most people got hurt around them when valves and fittings ruptured. Numerous boiler tenders were killed. Steam that is 180 F is a bad burn. Boilers were hotter than hell to work around in the summer, but probably pretty nice in the winter.
And you could always get your work clothes dried out after a good rain...
Boilers located too close to drilling rigs, or without regard for prevailing winds, caused many oil well fires in early history. It was not until 1918-1922 that blowout control methods began being developed in earnest; before then wells drilled with cable tool rigs were simply loaded with muddy water causing significant under-balancing. Wells would come in suddenly, splintering wooden derricks, sending flows high into the sky and saturating locations with associated natural gas. When this would happen hands would run, turn around and shout "shit," then make a mad dash to the boilers to shut steam off and douse fires, often to no avail.
In the rule of capture era wells were drilled so close together their derrick legs touched; if you lost control of a well somebody else's boilers might then set your well on fire, then other wooden derricks immediately down wind would catch on fire and calamity broke out. In places like Signal Hill, California, below, losing control of your well was often not ever neighborly.
Boilers, however, then played a major role in early oil well firefighting efforts as they could provide much needed water, under some level of pressure, that would keep men and steel cool while control efforts were implemented.