Meriam 70H_72H High Pressure Wet Tap Accutubes with Integral 3-Valve Head and Optional RTD - Manual (Page 17)

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the insertion flange of the packing housing. The head of the Accutube
during this procedure should be oriented so that the flow arrow agrees
with the flow direction within the pipe. During the initial insertion of
the probe tip into the packing housing, use care not to damage the
packing rings. Assemble the lower drive nuts with washers onto the
insertion/retraction rods. Thread the nuts upward until the washers
contact the insertion flange.
4.7.1.16 Lightly snug the packing gland socket head cap screws just enough to
set the packing in place and remove any clearances. Turn the hex
socket head cap screws each 1-1/4 turns to pre-load the packing rings.
Turn the screws a small amount alternately so as to tighten the
assembly slowly and evenly from both sides.
4.7.1.17 Verify the instrument valves on the Accutube head are closed.
4.7.1.18 Open the insertion valve. Verify all joints and packing are sealed
tightly as the entire assembly is now pressurized. The packing
assembly can be tightened further if required.
4.7.1.19 Insert the probe into pipeline by turning the lower drive nut counter
clockwise to pull the Accutube probe into the line. Both lower drive
nuts should be turned alternately so as to prevent uneven loading and
jamming of the Accutube assembly. Use this procedure until the probe
touches and stops on the opposite side of the pipe.
4.7.1.20 Withdraw the probe from the opposite end of the pipe wall 1/16” on
12” line size and less, or 1/8” on larger line sizes. This clearance is a
provision for thermal expansion allowances and assures centering port
holes.
4.7.1.21 Again inspect the packing gland assembly for leakage. If required,
tighten the packing screws an additional amount.
4.7.1.22 The Accutube is now in working condition.
4.7.2 INSTALLATION PROCEDURE- “½” AND 1” DIAMETER PROBES WITH
GEAR DRIVE
Follow steps 4.7.1.1 through 4.7.1.8. Then proceed with the following steps.
4.7.2.1 Assemble the packing gland housing assembly onto the other end of
the threaded cage pipe. Final position of this housing after it is securely
threaded in place should be such that the holes on the insertion flange
straddle the pipe centerline. This position determines the proper
orientation of the Accutube.
4.7.2.2 Assemble the packing rings (Grafoil) into the bore of the packing
housing. The ring must be handled with care. A broken ring is not
reusable. Substitution of alternate type packings will affect
pressure/temperature ratings of the assembly.
4.7.2.3 Assemble the cylindrical shape follower atop the packing rings and
into the packing housing.