Mounting a weld-in sight fitting: general principles
Why the welding and tightening sequences are defined by the manufacturer instructions, and what to verify before mounting.
Short answer
A weld-in fitting is mounted per the manufacturer instructions: choosing the welding sequence and tightening torques yourself is the main cause of later leaks and glass failures.
This material is an overview of general principles; it does not replace the instructions for the specific product and the vessel design.
Before welding
Verify the opening geometry, the access for welding and the effect of the vessel heat treatment. Agree the welding sequence if the wall carries a jacket or other penetrations nearby.
Welding and tightening
Tightening is performed with a torque-controlled tool in several passes per the manufacturer diagram. After thermal cycles and the first heating a check re-tightening is possible — only if the instructions allow it.
- do not tighten “by feel” — the glass is sensitive to misalignment;
- do not reuse deformed gaskets;
- record the actual torques in the mounting certificate.
Acceptance
Acceptance includes a visual inspection of the window, a leak test per the instructions and a record of the assembly parameters. Any deviation from the instructions is a reason to contact the manufacturer before start-up.