ST635 - Smith ST635 Heavy Duty Propane Heating Assembly

Technical Overview of the Smith ST635 Heating Tip

The Smith ST635 is a high-performance, heavy-duty heating tip assembly engineered specifically for industrial applications requiring substantial heat input using alternate fuel gases. Designed to operate with medium pressure Oxygen and Propane (or Natural Gas), this assembly is capable of generating an impressive average output of 614,195 BTUs. This level of thermal energy makes it an essential tool for heavy fabrication environments where rapid preheating, straightening, or bending of thick steel sections is required. The assembly features a fluted flame design which stabilizes the combustion process and ensures efficient heat transfer to the workpiece.

Physically, the ST635 is robustly constructed with an overall length of 31-1/2 inches. This extended length is a critical safety and comfort feature, allowing the operator to maintain a significant distance from the intense radiant heat generated during operation. The unit is designed to interface seamlessly with Smith Equipment's heavy-duty torch handles, specifically the WH200 and SW1B models. It is not compatible with standard medium-duty handles due to the high gas volume requirements.

Operational Requirements and Safety

Due to the massive volume of gas required to sustain over 600,000 BTUs, the ST635 has specific equipment prerequisites that must be adhered to for safe and proper function. Standard 1/4-inch hoses are insufficient; a 3/8-inch I.D. (10mm) hose is mandatory to prevent fuel starvation and backfires. Furthermore, the system requires a high-capacity regulator, such as the HB1522B-510 or 40-50-510, to maintain consistent delivery pressure.

Operators must also be aware of the withdrawal rates associated with this tip. Continuous use requires a substantial fuel source, such as a 100lb propane tank at 70 degrees Fahrenheit, or a manifold system connecting 2-4 smaller cylinders. Using insufficient fuel supply can leads to cylinder freeze-up and dangerous pressure drops. Additionally, high-flow flashback arrestors are required. Standard arrestors may create flow restrictions that necessitate increasing outlet pressures to compensate, ensuring the tip receives the necessary volume for stable combustion.