The integrity bchavior and life of a bolted joint depend a great deal upon the clamping force exerted by the bolts on that joint, Too high or little clamping force can lead to fa-tigue failure, damage or leaks, vibration loosening, slipping a nd cramping. As a result many efforts have been made to solve the problem [1], [2], [3], We have developed a system that tests thestress from it. The influence of temperature within the range of 20-360℃ is au-tomatically compensated. This equipment not only can moni-tor the stress during its assembling, but also at high tempera ture and will alarm when the bolt stress has serious changes, This alarm can win some time for us to take emergency measures to avoid disasters.

In view of the adoption of the International Temperature Scale of 1990 (ITS-90) which defines the International Celsius Temperatures t90, the dependence on temperature of the speed of sound in seawater is reexamined. The coefficients for two seawater sound-speed equations published previously, one by UNESCO (1983) which is also known as the Chen and Millero equation fo 1977, and one by DelGrosso (1974) are revised for application with the new temperature scale ITS-90. It is found that the resulting change in seawater sound speed is within 0.024 and 0.017m/s for the UNESCO and the DelGrosso equations, respectively, These changes are comparable to the numerical correction values suggested by Dushaw et al. (1993)

A high temperature bolt stress monitor, based on the testing of the Transit Time of Lo ngitudinal Wave and Shear Wave (TTLSW for short) and on the calculation of the stress through the established stress vs TTLSW equation, has been developed and tested. Lithium Niobate was used for piezoelectric material, gold or silver films were used for coupling material an clamping together method was used to install the transducer. Time interval areaging, zero crossing detect and several other techniques were used to improve the accuracy of TTLSW measurement. Using this method within the range of 30-360℃, and 0-443MPa the accuracy of stress is better than 9.8MPa.

The princples, consturction. Error analysis and insite measurement resnlts of the Digitized Pressure Difference Meter are Presented. Its accuracy measured by the China National Institute of Metrology in the range of 0-120mm is 0.03%