Fasteners in rivetless connection special aircraft are common parts, some mechanical equipment to work under high temperature, such as boiler, steam turbine, etc., resulting in mechanical fasteners are also affected by high temperature and their performance, resulting in failure. The following measures should be taken when fasteners are used at high temperature.

1, sealing stress: to ensure the sealing of connecting parts is a basic requirement of bolt connection. The sealing stress is determined by the tightening force of bolts when the geometry of flange, machining quality of joint surface, steam pressure and temperature remain unchanged.

2, temperature stress: the unit in the start, operation, because there is a temperature difference between the flange and bolt, and the linear expansion coefficient of the two materials is different, the free thermal expansion of the flange is larger than the bolt, the bolt is subjected to an additional tension, the additional tension in the bolt caused by the stress called temperature stress.

3, the bolt heat tightness: in the installation of the bolt by the pretightening force, when cast into operation, under the action of steam pressure, the bolt force than the initial pretightening force has increased, for the general horizontal flange, bolt tension force increased by 5%-15%, so that the initial stress of the bolt cold tightness can be lower than some.

No matter what method is adopted, it is to tighten the mechanical equipment and prevent failure, so we must understand the measures of fasteners at high temperature, so as not to fail the performance of fasteners, resulting in accidents.