1. n. [Drilling]
A cheap, expendable, perhaps even disposable threaded shape to mate with threads on drillstring and casing components. Thread protectors prevent harmful impacts and other contact to the metal thread surfaces. Some protectors are strong enough and are fitted with lifting eyes so that they may be screwed into a joint of drillpipe, a drill collar or another component and a chain tied to the eye for lifting the joint. Except for this type, most of the other available styles of thread protectors are relatively inexpensive, being made from thermoplastics and various epoxy resins.
See: drill collar
2. n. [Well Completions]
A protective sleeve or cap generally made up on the threads of tubular goods during transport and storage. Thread protectors are available in metal, plastic, or a combination of both.