The shape of the rod bolts (screws) are divided into the following groups: a) with a normal rod, and b) with podgolovkoy c) with a thickened stem purely handled by installing a deployed without opening the gap to prevent shifting under load connected parts: i) with a rod of reduced diameter to reduce the stress concentration at the thread and better perception of the variables and shock loads. For convenience of assembly and disassembly of the minimum distance between the bolts must be at least (5 – 6) d when using the patch and key for at least (3 – 5) d when using the Allen key. The special bolts include: Anchor, tapered, hinged, trucks and others. Anchor bolts used to secure vehicles on the foundation and made in the form of long rods with threaded end. They can be divided structurally: on the bolts with a constant incorporation – for equipment not subject to rearrangement, the bolts that allow the recess without destroying the foundations for equipment interchanged when changing products in a sustainable production. Banjo bolts (screws) are in the head a ring, for securing the screw head for this transverse axis, it can be rotated around the axis (recline) and quickly release the connecting parts (accessories). The main criterion of efficiency bolt compound is the strength of the rod bolt.

Bolts with thickened purely processed (polished) for the core hole of a sweep is calculated by cutting and crushing the side surface under the action of high shear loads. These bolts are not tightened. Most of the bolt connections are installed in the holes held together with a clearance of parts. Therefore, these bolts regardless of the direction of external loads are calculated from the tensile taking into account the twisting of the rod point of friction in the thread. In these compounds, the bolts are tightened pre-tightening torque, which is under the influence of shear stress is part of the conditions of mutual immobility details and determines the diameter of the bolt.

A more general calculation of the strength of the bolted connection, especially for pipe fittings, tanks, boilers, chemical production units, is the calculation of the flange bolts Connection cap with the cylinder, is under internal pressure p. The calculation is made on the condition of tightness of the connection. Gasket sealing element is ring-shaped with a diameter of D1 and D2. It should shrink pressure considerably exceeding the pressure in the cylinder. Deformed by this pressure, the gasket fills the irregularities of contacting surfaces and prevents leakage of fluid or gas cylinder. When variables external loads is checked the bolts on the stock on the fatigue strength.