Tubular goods whose use includes, but is not limited to, use in the drilling for, and production of oil and gas, experience a considerable amount of handling and a certain degree of mishandling and abuse on their journey from the steel mill to the final well destination. As a result, screw on cylindrical thread protectors with a full compliment of threads are placed on such tubular goods to protect the threads from any harm prior to installation. However, because the removal of such protectors often requires an expenditure of time that cannot be tolerated during the installation of tubular strings in wells, the original protector is often removed at the well site and is replaced with a different protector with quick release and installation capabilities. The tubular good subsequently rides from rack to rig with the new thread protector which is eventually removed when the joint is to be threadedly attached to the downwardly continuing string. During the interval that the protector is on the threads, a last bore drift test is usually done and it is desirable that the protector does not interfere with the drift passage. Once the string is pulled out of the hole, the quick install capabilities of such a thread protector ensure protection for the threads on tubular goods whose threads have not been damaged in the drilling activity.
A considerable amount of development work has been done in efforts to improve the bands and related tensioning gear to keep the casing protectors from being knocked off the threads during the rack to well trip.
The body of protectors in rig site use are currently made of elastomer, sometimes polyurethane, but may sometimes be made of other material, such as black rubber. The elastomer is formulated and cured to serve the skid and bash protection function and does not always favor thread gripping. In order for the elastomer to adequately grip the threads on the tubular goods to be protected, a sufficient amount of hoop force must be applied, which is often accomplished through the tensioning of bands around the elastomer. However, such securing bands are designed to be tensioned by hand and consequently, seldom have enough energy to drive the elastomer into the thread grooves sufficiently to prevent the occasional slipping of the protector.
Furthermore, the thread protectors on the rig site are currently designed so that the elastomer is pulled apart to accommodate the threads to be protected and subsequently tightened around such threads when the protector is in place. The net effect of repetitive pulling apart is that the elastomer would eventually deform due to the repetitive yielding, causing the elastomer to lose its memory characteristics.
USPTO Backgrounds
USPTO Backgrounds