How should tubes be attached in drum holes?

How should tubes be attached in drum holes?

• A. Welded
• B. Clamped
• C. Rolled
• D. Bolted

Answer: (C)

Tubes are attached by rolling (expanding) the tube ends into the drum holes. This mechanical expansion forms a tight rolled joint that flares slightly against the drum hole walls, creating a secure, leak-tight connection that can withstand the high pressure and the thermal expansion and contraction of the tubes during operation. Rolling avoids the heat input and potential distortion that welding would introduce, and it provides a durable bond that’s easier to inspect or replace later. Clamping or bolting wouldn’t seal against steam and could loosen under vibration, while welding isn’t practical for these joints in a boiler drum.

Tubes are attached by rolling (expanding) the tube ends into the drum holes. This mechanical expansion forms a tight rolled joint that flares slightly against the drum hole walls, creating a secure, leak-tight connection that can withstand the high pressure and the thermal expansion and contraction of the tubes during operation. Rolling avoids the heat input and potential distortion that welding would introduce, and it provides a durable bond that’s easier to inspect or replace later. Clamping or bolting wouldn’t seal against steam and could loosen under vibration, while welding isn’t practical for these joints in a boiler drum.