Meriam 70H_72H High Pressure Wet Tap Accutubes with Integral 3-Valve Head and Optional RTD - Manual (Page 19)

19
4.7.3.3 Weld the Weld-O-Let in place in the pipe. The Weld-O-Let is to be
positioned so that it is perpendicular to the centerline of the pipe and
square to the surface of the pipe. The Weld-O-Let has a special
designed I.D. to guide and support the drill and probe.
4.7.3.4 Assemble a weld neck flange onto the Weld-O-Let. Tack weld in place
so that the flange holes straddle the pipe centerline. Verify alignment
and finish the weld.
4.7.3.5 Assemble the insertion valve onto the flange with a gasket in place and
fasten with bolts. Final position should be such that the stem of the
valve is parallel to the centerline of the pipe. This assures clearance of
the valve handle with the insertion/retraction rod. Use a flat washer
with each bolt and nut. First hand-tighten each bolt. Use a criss-cross
or star pattern to tighten bolts. Check tightness 24 hours after
installation.
4.7.3.6 Attach the drilling equipment to the insertion valve. Drill size should
be 2-1/2” in diameter. Operate the pressure drilling equipment in
accordance with manufacturer’s instructions.
4.7.3.7 After the drill has penetrated the pipe, withdraw the spindle on the drill
and close the insertion valve. The assembly is pressurized. Open vent
valve on drill or slowly loosen the drilling assembly to vent pressure.
4.7.3.8 Remove the drill from the insertion valve.
4.7.3.9 Weld the weld neck flange to the cage pipe.
4.7.3.10 Weld the packing gland housing onto the opposite end of cage pipe. A
1/16” gap must be left inside the socket of the housing prior to
welding. The two insertion rod holes in the lower insertion bar of the
packing gland housing must straddle the bolt holes in the weld neck
flanges.
4.7.3.11 Assemble the packing rings (Grafoil) into the bore on the packing
housing. The rings must be handled with care. A broken ring is not
reusable. Substitution of alternate type packings will affect
pressure/temperature ratings of the assembly.
4.7.3.12 Assemble the cylindrical shape follower atop the packing rings into the
packing housing.
4.7.3.13 The retainer is now placed atop the follower and secured loosely with
the socket head cap screws. Do not tighten the screws at this point.
4.7.3.14 Assemble the packing gland housing/extension subassembly onto the
valve with the remaining gasket located between the flanges. Final
position of this assembly, when bolted in place should be such that the
holes on the lower insertion bar straddle the pipe centerline. This
position determines the proper orientation of the Accutube probe when
assembled in place.
4.7.3.15 Assemble the instrument valves onto the Accutube probe head.