average value of load error due to the thread forming and adjust the zero load measurement or target tightening parameter to compensate for this effect using one of the above described methods this approach however does not compensate for variations with individual fasteners or joint components and is therefore presently considered less desirable the result is that for the first time ultrasonic load measurement technology can be used with thread forming fasteners errors in load measurement resulting from the thermal effects of thread forming can be compensated this then results in accurate load measurement and tightening control of the thread forming fasteners the above described method of eliminating the effects of fastener heating resulting from the thread forming process can also be used with other fastener assembly processes that generate heat prior to the load inducing tightening stage thread locking bolts and nuts for example are manufactured with a prevailing u201c locking u201d torque to prevent the fastener from loosening during service most often the thread of either the bolt or nut has an irregular profile causing the threads to elastically deform slightly upon mating alternatively the bolt or nut has an insert or patch of a soft material to provide the prevailing torque or resistance to loosening the prevailing torque provided by these thread locking features produces heating of the fastener during rundown in the same manner as the tapping torque does with a thread forming fastener consequently the above described method for compensating for thermal related errors in accordance with the present invention can be used with prevailing torque locking fasteners to improve the accuracy of ultrasonic load measurement during assembly it will.