Two-piece drilling flange

摘要

This invention relates to a two-piece drilling flange which allows for the full engagement of a conventional casing head external thread (8-round thread) reducing thread wear. The two-piece drilling flange incorporates a flange-bushing piece and a drilling-flange piece. The flange-bushing piece is hand tightened on the 8-round thread so that the casing head end face protrudes beyond the bushing. The drilling-flange piece is threaded onto the flange-bushing piece until a highly reliable elastomeric radial seal makes tight contact with the casing head end face. The drilling-flange piece is then further tightened, exerting an upward force on the flange-bushing piece, ensuring the full engagement of the casing head 8-round thread by the flange-bushing piece internal thread. This tight thread fit reduces thread wear by preventing destructive movement between the threads, especially during the highly vibrating drilling process.