In boiler tube maintenance, what devices are used to expand tubes within mud and steam drums?

• A. Mandrels and rollers
• B. Hydraulic jacks
• C. Rolling motors and espanders
• D. Saws and grinders

Answer: (C)

Expanding the tube ends to fit tightly in the mud and steam drum openings is what creates a secure, leak-tight joint under boiler service. The tools used for this are rolling motors and expanders (often called espanders). The rolling motors work with rollers to apply controlled deformation to the tube end, preparing it for the final, precise sizing. The expander then enlarges the tube end to create an interference fit against the hole in the tube sheet, holding the tube firmly in place even under high temperature and pressure. This combination provides the reliable expansion needed for boiler tubes.

Hydraulic jacks don’t provide the precise, controlled expansion needed; saws and grinders are for cutting and finishing, not expanding; mandrels and rollers alone don’t achieve the full expansion action required.