Threaded inserts are simply fasteners which are inserted into different elements to put in a threaded hole. In other words they are the threaded bushings that you would have seen or used in many of your devices ranging from small and big. These inserts are used for many purposes including cast or mold threads. They make a threaded hole in all sorts of material and also used for repairing a hole which is stripped.
The most common happenings while working with such heavy systems and Hydraulic Valves are accidents and mishaps. So the operator has to be very careful in correctly fixing the valves inside the system so that the possible leakages can be avoided – do you even try this pump? There should be a checklist to ensure that the system is ready to start the process before actually working with it.