WorldWide Drilling Resource

Maintaining Critical Joints Despite Tough Demands Adapted from Information Provided by STANLEY Engineered Fastening From downhole to topside, onshore to offshore, oil rigs operate in some of the most extreme environments on earth. The need to drill deeper, farther, in hotter, colder, and increasingly remote locations has made oil rig reliability and serviceability more crucial than ever. Despite ever-increasing oper- ational shock, vibration, and temperature demands, critical joints must be maintained and production downtime minimized. Tapped holes and fasteners holding vital equipment together must operate with virtually no margin for error to avoid the astronomical cost of production downtime and unsched- uled service to million-dollar equipment. Traditional locking fasten- ers don’t deal with a basic de- sign issue: the gap between the crest of male and female threads can lead to vibration-induced thread loosening. Stress concentration and fatigue risk at the first few engaged threads is also cause for concern. Temperature ex- tremes can expand or contract surfaces and materials, potentially compromising important connections. A unique internal thread form is helping the oil industry enhance reliability and productivity by resisting shock, vibration, and thread loosening, as well as extreme temperatures, even in hard-to- cut, super alloy materials. This state-of-the-art thread form also enables extensive reusability in the field. Innovative Spiralock ® self-locking threaded fasteners can be used in a range of oil and gas applications, from MWD chassis, top drives, reamers, and set screws, to high-pressure compressor valves, and even mining shakers and separators for oil sands operations. The Spiralock adds a 30-degree wedge ramp at the root of the female thread which mates with standard 60-degree male thread fasteners. The wedge ramp allows the bolt to spin freely in relation to female threads until tension is created in the male fastener. The crests of the standard male thread form are then drawn tightly against the wedge ramp, eliminating radial clear- ances and creating a continuous spiral line contact along the entire length of the thread engagement. The continuous line of con- tact spreads clamp force more evenly over all engaged threads. In National Aeronautics and Space Administration (NASA) tests, Spiralock thread fasteners were used in the main engines of the Orbiter, with its tremendous launch vibrations and repeat servicing requirements. The thread fasteners deliv- ered 50 uses with no loss of clamp load. 38 AUGUST 2015 WorldWide Drilling Resource ®