1966 Orr & Sembower 350 HP 3‑pass firetube natural‑gas boiler

Specs
Year: 1966
Make: Orr & Sembower
Model: 3HGBoiler
Type: Firetube (three‑pass design, packaged)
Power: 350 HP
Capacity: 11,716,250 BTU/hrMax Working
Pressure: 15 psi
Heating Surface: 1,750 sq ft
Gas Consumption Rate: 13,825 cu ft/hr
Voltage – Motors: 208 V, 3‑phaseVoltage – Controls: 120 V, 1‑phase

Installed Options
Natural gas burner assembly
Electric motor drive system
Inline safety and pressure instrumentation
Exhaust stack support structure

Feature Spotlight
Three‑pass firetube construction optimizes fuel-to-steam efficiency• Large 1,750 sq ft heating surface accommodates high steam volume
Fitted with industrial burner for natural gas operation
Electric configuration with dual-voltage control and motor support
Visible gauge and control interface for real-time pressure monitoring

Machine Overview

This Orr & Sembower 3HG boiler is a 350 horsepower, three-pass packaged firetube boiler built in 1966 and designed for natural gas fuel. It features a firing capacity of 11.7 million BTU/hr, a 15 PSI maximum working pressure, and a 1,750 sq ft heating surface. The burner system consumes 13,825 cu ft/hr of gas and is powered by a 208 V, 3‑phase motor, with controls operating at 120 V, 1‑phase. The boiler includes key safety features such as integrated gauges and exhaust stack support. Condition appears operational, and external wear is consistent with industrial use.