Stainless Steel, Quadruple Pass / Quadruple Helix Coil 0 An example of a stainless steel, quadruple pass (4 inlets/outlets), quadruple helix (4 coils nested inside each other) coil. An example of a stainless steel, quadruple pass (4 inlets/outlets), quadruple helix (4 coils nested inside each other) coil.