Vessels Have a Duran Style O-Ring Flange. Flanges Can Either be Sealed with an O-Ring or Grease. Cirulatory Jacket is Offered with Detachable Hose Barbs. Internal Threaded Ports are Supplied with Nylon Bushings and Polypropylene Barbs. For Clamps See PRG-188 and O-Rings See PRG-187. Drain Valve 0-12mm Seats Flush to Interior Radius Bottom.