For specific applications where copper is required, the copper/stainless steel BiMetl flange provides a stainless steel all-metal seal. The copper is explosively bonded to stainless steel, then machined into your desired configuration. No brazing is used.

Every flange is thermally cycled to over 300°C and helium leak-checked, to a sensitivity of 5 x 10^-10 std cc He/sec, before and after thermal cycling.