Steel Couplings, Series 411 (COUP 4" S/B 411-045001-003)

COUP 4" S/B 411-045001-003|Smith-Blair’s 411 steel couplings consist of one cylindrical sleeve with conical inner surfaces at each end; two resilient, wedge-shaped, specially-compounded rubber gaskets; two ring-shaped followers and a set of high-strength, low-allow track-head, oval-neck, rolled-thread bolts with heavy hex nuts. Properly selected and installed flexible couplings maintain the continuity of the piping system, retain the line contents under internal pressure and prevent infiltration under vacuum.