... Iron Checked by Go&no go gauge 4"NPT thread Machined by CNC and NC Machine Sand Casting Pump Inlet FlangeGrey IronChecked ... "NPT threadOil coatedSuperior corrosion resistanceMachined by CNC and NC MachineCheck 4"NPT thread by gaugeStandard: ASTM, BF,BS, JIS, UNI, ... , Boring, Slating, Grinding,, NC/CNC Machining etc.4) Tolerance is controlled by CMM Machine.5) OEM Service6) Special design is available.7 ...