The formula for screw joints applies under the condition that all screws have the same diameter and the length L is less than 15 * d
The force that tries to pull the joint apart
Number of screws
The number of screws in the joint.
Refers to the diameter of each of the individual screws.
Refers to the length of the dressing in accordance with the figure below.
Force of union
The force the joint can handle before the screws go off.