What are the welds called that are performed on parts of a pressure vessel that contain internal forces?

The welds referred to in the context of pressure vessels, which contain internal forces, are known as pressure boundary welds. This term specifically identifies the joints that are critical in establishing and maintaining the integrity of the pressure vessel's boundary. These welds are vital because they ensure that the pressure from the contained fluid does not escape, thus maintaining the safety and operational effectiveness of the vessel.

Pressure boundary welds contribute to the overall strength and stability of a pressure vessel, as they are designed to withstand the stresses imposed by internal pressures. These welds are subject to rigorous standards and inspections to confirm their ability to perform under high-pressure conditions.

The other options, while they might imply relevance to pressure management or containment, do not accurately refer to the specific type of welds that directly deal with the structural integrity necessary for containing internal forces within a pressure vessel. Instead, pressure boundary welds are the precise terminology used in industry standards and practices for this critical aspect of pressure vessel construction.