The Pressure seal bonnet (PSB) check valves
provided by Weldon are adopted for high pressure service. Compared to Bolted Bonnet (BB) check valve, which the body flange and bonnet flange are joined by studs and nuts, when the system pressure increases, the potential for leakage through the body / Bonnet joint also increases, the unique structure of the pressure seal Bonnet
is that the body-Bonnet joints seals improves as the internal pressure in the PSB check valve
increases, the higher the internal pressure, the greater the sealing force.