Relief Valve Pilot Lines:For 9390 model relief valves (DN 150 (6”) and smaller, see item 1), the pilot line shall be ½” x 0.0035” wall Stainless steel tubing with tubing adapters (double ferrule compression by MNPT) at each end.For 9340 model relief valves (DN 200 (8”) and larger, see item 1), the pilot line shall be ¾” schedule 40S Stainless steel pipe.Thicker wall tube or pipe shall not be used.