Which method is used to attach tubes in drum holes?

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

Answer: (A)

Tubes are attached to a boiler drum using a rolled joint. In this method, the tube is inserted through a hole in the drum and then the end of the tube is rolled or formed so that it expands and bears against the drum wall. This deformation creates a tight, leak‑tight seal and a secure mechanical hold without welding or threading. The rolling process eliminates heat input at the joint, avoiding heat-affected distortion and providing good resistance to the high-pressure steam and thermal cycling inside a boiler. Because of these advantages, rolled joints are standard for attaching tubes in drum holes. Screwed, bolted, or welded joints would introduce threads, fasteners, or heat-related weaknesses that are less reliable under boiler conditions.