1. The pre-tightening force of the bolt material shall be calculated theoretically according to the working requirements, so as to put forward requirements for the tensile force and tensile length of the hydraulic tensioner.

2. The length of the bolt extending out of the nut should be greater than or equal to one time of the bolt diameter, and there should be a certain working space around the bolt. The contact reference plane of the hydraulic tensioner support ring must be flat to ensure the smooth stretching operation.

3. If the bolt stretching process is used, the following requirements are required for the nut:

a) Use round nuts as much as possible so that they can be moved when tightening. If hexagon nuts are used, put an inner hexagon ring on the hexagon nut to facilitate the rotation of the hexagon nut.

b) The thickness of the nut shall be lower than the height of the support ring of the hydraulic tensioner, and a gap of not less than the stretching length shall be reserved.