A bottom mounted drain nozzle should be fit-up flush to which surface?

A bottom mounted drain nozzle should be fit-up flush to which surface?

• A. Inside
• B. Outside
• C. Top
• D. Bottom

Answer: (A)

When attaching a bottom-mounted drain nozzle, the most important goal is to maintain a smooth interior boundary. Fit-up flush to the inside surface keeps the interior contour continuous around the nozzle, so there’s no protruding lip or recessed edge inside the vessel. This smooth interior path is key for effective drainage and easy cleaning. A flush inner surface minimizes areas where liquid can stagnate, reduces flow disruption, and helps avoid trapping solids near the nozzle. It also supports a cleaner weld transition from the inside and keeps the interior weld area accessible for inspection. If the fit-up were flush to the outside, or if it created an interior step, you’d introduce a discontinuity inside the vessel that can trap residue, increase corrosion risk, and hinder drainage. That’s why aligning the nozzle so its inner face sits flush with the vessel’s interior surface is the correct approach.

When attaching a bottom-mounted drain nozzle, the most important goal is to maintain a smooth interior boundary. Fit-up flush to the inside surface keeps the interior contour continuous around the nozzle, so there’s no protruding lip or recessed edge inside the vessel.

This smooth interior path is key for effective drainage and easy cleaning. A flush inner surface minimizes areas where liquid can stagnate, reduces flow disruption, and helps avoid trapping solids near the nozzle. It also supports a cleaner weld transition from the inside and keeps the interior weld area accessible for inspection.

If the fit-up were flush to the outside, or if it created an interior step, you’d introduce a discontinuity inside the vessel that can trap residue, increase corrosion risk, and hinder drainage. That’s why aligning the nozzle so its inner face sits flush with the vessel’s interior surface is the correct approach.