(26d) Inspection Methods for Schmidt’Sche® Transfer Line Exchangers (TLEs) during Shut-Downs

ARVOS SCHMIDTSCHE SCHACK (formerly part of ALSTOM) has supplied over 9000 TLEs to the Ethylene industry since 1959. Schmidt’sche^® TLEs are installed directly downstream of the furnace radiant coils, and rapidly cool the cracked gas by producing high pressure steam. Deterioration of TLEs occurs over time, due to gas-side erosion, or water-side corrosion.

To understand the status quo and ensure the lifetime of the heat exchangers, periodic inspection and maintenance is required. The following paper describes SCHMIDTSCHE SCHACK’s recommended best practices for inspection of TLEs during shutdowns. The paper will provide inspection options to assess the condition of TLEs depending on the plant’s operating parameters and feasible inspection points depending on shut-down duration.

The guidelines discussed will include inspection methods, for example, water-side endoscopy, wall-thickness measurement testing, and tube straightness evaluation. Based on the inspection results the suggested follow-up actions will be defined, such as water side flushing, inner tube replacement and plugging, and partial oval-header replacement.