A link between hydraulic and tube joints. What is commonly used to prevent leakage
If it is ultra high pressure seal (70mpa), it can be fitted with a metal taper, which is the slant of the pipe and the diagonal of the component thread.
If it is a cylinder thread, depending on the pressure, you can use the combination washer, copper washer, o-ring, ring, circle, etc
If it is a tapered thread, it can be wrapped in raw material and sealant
