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On top of these benefits, MJTs provide precise tightening control, which is critical for sensitive applications such as gasketed flanges. They also stay in place and remain on equipment until removal for the next outage, assuming the joint was properly designed in the first place.
MJT's add elasticity to any bolted joint. Elasticity enables a material to return to its original form or condition after an applied force is removed. Thus, increased bolting elasticity can compensate for flange and joint instability due to temperature changes, changes in internal pressure, and joint movement. Long, highly stressed bolts can provide high levels of elasticity, while short bolts may require disc springs under the nut or bolt head to obtain sufficient elasticity. One alternative, albeit a somewhat clumsy one, is to replace the stubby bolt with a longer one and add spacers to take up the slack. A better option is to use an MJT system, which provides the elasticity needed to preserve bolted-joint integrity. Radial flexing of the nut reduces stress concentrations that could otherwise cause threads to break in the bolt or stud (Figure 5: Increased elasticity of MJTs on high-temperature flange and joint applications is critical to permanent sealing under operating conditions). Because of their elastic properties, MJTs have helped seal many leaky joints.
The fact that MJTs are space-efficient hasn't been ignored by some OEMs looking to decrease the overall size of their machinery housings. This is because the stud-to-stud spacing can be tighter using MJTs, and you no longer have to manipulate large, heavy equipment for installation and removal.
ConclusionEach application presents a unique set of challenges and problems. There are several options available today to achieve a properly bolted joint. Consider the specific demands of your application and choose a bolting method that best fits your needs.
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