FUEL SYSTEM 25 STEP 4 Add PTFE thread tape, 3 turns to the male NPT threads STEP 5 Tighten the male end-connection into the female end-connection until finger-tight. STEP 6 Tighten the male end-connection until wrench-tight. CAUTION: Use an appropriate sized wrench. An oversized wrench will permit over-tightening and might lead to galling of the threads. There is no standard for torque or number of turns. ANSI/ASME B1.20.1 – 1983 STATES, “NPT TAPER PIPE THREADS ARE INTENDED TO BE MADE UP WRENCH-TIGHT WHENEVER A PRESSURE-TIGHT JOINT IS REQUIRED. “do not over-tighten so much as to strip the threads. Once tight, do not loosen the connection. Doing so could lead to leakage at the pipe thread. STEP 7 Using a permanent marker, place a mark on the exposed threads. This mark is used to indicate that the connection has been tightened wrench-tight. STEP 8 1 A line inspector or second individual must then check the connection to verify assembly has been sufficiently tightened. 2 Place a second mark on the exposed threads alongside the first mark, after ensuring tightness of the assembly. 7
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