Small Steam Boilers Model UMB-64

This calculation shows that even with 60% weld efficiency and safety factor of 2, this boiler could operate at almost 800 psi.  In reality the operating pressure could be even higher because the weld efficiency is above 90 % . Under no circumstances do we recommend that you would operate these boilers at such a pressure. The above calculation is to demonstrate the safety factor built into our boilers.  All boiler trim, sight glass, valves, and fittings are designed for 250 psi working pressure, hence we limit working pressure up to 230 psi with 250 psi safety valve blow off.
Firewood up to 24 inches (60 cm) in length can be used to fire  model UMB-64 boiler.
FOB retail price for UMB-64 boiler with enclosure -  US$ 5,000.00

TS         = Tensile Strength of material in psi
t            =  thickness of material in thousands of inch
E           =  Efficiency of weld in %
R          =  Radius of steam drum in inches
FS         =  Factor of Safety
MAWP = Maximum Allowable Working Pressure

                                     36,000  x  .3125  x  .6
                                    -----------------------------  =  793.35 psi (54.7 bar)
                                             4.250  x  2

                                                      TS   x  t  x  E
                                                     -------------------  = M A W P
                                                          R  x  FS

Model UMB-64
This boiler has a total heating surface area of 64 square feet (5.94 square meters), and it
is designed for firing with wood. Boiler is designed for stationary applications, therefore,  heavy duty construction is used throughout.  Operating pressure is up to 230 psi (15.8 bar) with safety valve blow off pressure set at 250 psi (17.2bar). The safety valve is ASME certified.  Boiler is hydrostatically pressure tested to 600 psi, hence it has plenty of safety factor built into it. As a matter of fact this boiler could operate at almost 800 psi (55.1 bar) pressure according to Maximum Allowable Working Pressure calculation.