For pipework installations that operate at higher temperatures or pressures than can be tolerated by soft capillary soldered fittings, e.g. steam services, or where grease-based fluxes are prohibited e.g. oxygen lines, a range of high-duty fittings is available. High-duty fittings usually contain integral rings of silver brazing alloy, though end-feed types are also available.
Melting points for brazing filler metals can be around 650oC, much higher than the 220 - 240oC typical for solder filler metals.