The construction shown on the picture is the Badotherm solid front safety pattern gauge (BDT20) with an ECB welded seal and a BSO-02 filling fluid (suitable up to 400 degrees Celsius). The construction, with the seal upper part, designed to match with the threads of the process gauge, is welded to the pressure gauge connection, and the lower part with threading matching the process connection. The welding of the pressure gauge onto the diaphragm seal eliminates the potential loss of system fill fluid through the threads in case of failing gaskets.
Second advantage is that the gauge cannot be easily dismantled from the Diaphragm Seal, and reduces the risk of wrong disassembly. The ECB threaded seal design has the upper and lower part welded together, with no use of bolts or gasket and thus no risk of bolts loosening due to temperature fluctuations or vibrations. This construction doesn’t need O-rings or gaskets, which eliminates the risk of wrong gasket selection and/or leakages through the gasket.