Joint calculations
The basic equations of EN 1591

Problem: note that EN 1591 applies to a seated sequence, then to a situation (under pressure) without further tightening. In fact, when we study an assembly (for example, in five subsequent situations) according to EN 1591, we study the following sequences: seated then situation 1, and seated then situation 2, etc., in parallel.

So we place ourselves at an operating point (stress on the joint at the seat) and consider that we are working in decompression to reach the situation corresponding to pressure I.