Development of Dope-Free Premium Connections for Casing and Tubing

摘要

Removing API dope from the makeup process of threaded premium connections during casing and tubing operations not only reduces the risk of contamination of the local environment but also provides a cleaner and safer working area. Conversely, the removal of the antigalling property inherent in API dope greatly increases the risk of galling damage to connections during power-tight makeup. This paper describes various tests carried out to evaluate manufacturers' claims of having successfully improved the galling resistance of premium connections by electro-depositing a white bronze (45%Cu-55%Sn) alloy onto couplings manufactured from high-chrome materials. Galling resistance was measured by subjecting several test coupons plated with copper and various alloy compositions to a series of tests designed to generate high stresses to threaded surfaces. The paper also shows through experimentation how the correct amount of preload was achieved in a premium connection's gas-tight seal by applying a thin lubricating layer (also referred to as a protective film) to both pin and box threads.