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Multi-jackbolt tensioners (MJTs), registered under the trademark Superbolt or Supernut, are designed to decrease the torque required to tighten large bolted joints. One of the major problems associated with traditional bolt tightening methods is as the diameter of the bolt increases, the amount of torque required to tighten it increases in the third power of the diameter. [1]
These practices are not a means of obtaining or maintaining torque, rather a safety device to prevent the disengagement of screws, nuts, bolts, snap rings, oil caps, drain cocks, valves, and parts. Three basic methods are used in safetying; safety-wire, cotter pins, and self-locking nuts. Retainer washers and pal nuts are also sometimes used. [2]
A plain washer and a spring washer are placed on a bolt between the nut (on the threaded end) and the bolt head. The American National Standards Institute (ANSI) provides standards for general use flat washers. Type A is a series of steel washers at broad tolerances, where precision is not critical.
A safety wire is used to ensure proper security for a fastener. The wire needed is long enough to reach from a fixed location to a hole in the removable fastener, such as a pin — a clevis fastener, sometimes a linchpin or hitch-pin through a clevis yoke for instance — and the wire pulled back upon itself, parallel to its other end, then twisted, a single end inserted through a fastener ...
Upon installation, tiebacks are tested and usually pre-loaded. In specific, a combination of proof tests and performance tests are performed on every job. Proof testing involves the application of successively larger loads on the tieback with a loading jack, allowing for the recording of a load-elongation curve according to gauge readings.
A retaining ring is a fastener that holds components or assemblies onto a shaft or in a housing/bore when installed - typically in a groove - for one time use only. Once installed, the exposed portion acts as a shoulder which retains the specific component or assembly.
It is therefore beneficial in high-frequency high-load situations with a higher risk of fatigue related failure, like a bolted down cylinder head, to use torque to yield bolts. [ citation needed ] The torque applied to the fastener must be determined such that it does not contribute to a service condition where the fastener enters a low-cycle ...
A cast-in-place anchor bolt. The simplest – and strongest – form of anchor bolt is cast-in-place, with its embedded end consisting of a standard hexagonal head bolt and washer, 90-bend, or some sort of forged or welded flange (see also stud welding). The last are used in concrete-steel composite structures as shear connectors. [6]