HOIS Highlights 2023-2024

Flange face corrosion is a threat to the integrity of pressure vessels and pipework. Inspection of flanges has an important role in assuring the integrity of pressure equipment.

The breaking of a flange to visually inspect the condition of the sealing surface is time-consuming and requires the shutdown of the system. The inspection itself can introduce additional corrosion risks by allowing air ingress into sealed systems. Non-intrusive inspection of flanges has both safety and cost benefits. Flange inspection is a consideration in pressure vessel NII scopes.

The HOIS recommended practice for in-service inspection of raised face (RF) flanges using phased array ultrasonic techniques was issued in 2012. It has not been updated since then, it is also restricted to RF flanges and does not include recommendations for ring type joint (RTJ) flanges which are commonly used.

Trials have been conducted on both raised face and ring type joint geometries in carbon steel and stainless steel.