Fire-tube Boiler - Safety Considerations

Safety Considerations

Because the fire-flume boiler itself is the pressure vessel, it requires a number of safety features to prevent mechanical failure. Boiler explosion, which is a type of BLEVE (Boiling Liquid Expanding Vapor Explosion), can be devastating.

• Safety valves release steam before a dangerous pressure can be built up

• Fusible plugs over the firebox melt at a temperature lower than that of the firebox plates, thereby warning the operators by the noisy escape of steam if the water level is too low to cool the firebox crown safely.

• Stays, or ties, physically link the firebox and boiler casing, preventing them from warping. Since any corrosion is hidden, the stays may have longitudinal holes, called tell-tales, drilled in them which leak before they become unsafe.

The fire-tube type boiler that was used in the Stanley Steamer automobile had several hundred tubes which were weaker than the outer shell of the boiler, making an explosion virtually impossible as the tubes would fail and leak long before the boiler exploded. In nearly 100 years since the Stanleys were first produced, no Stanley boiler has ever exploded.