Meriam 70H_72H High Pressure Wet Tap Accutubes with Integral 3-Valve Head and Optional RTD - Manual (Page 13)

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4.4.4 Place the gasket on top of the weld neck flange and insert the Accutube to verify
alignment of the probe and clearance. Alignment of the probe must be within
the limits shown in Figure 4.1. The probe tip should clear the inside wall of the
pipe by 1/16” on 12” and smaller line sizes, and 1/8” on larger line sizes (this
clearance will occur within the support plug on Series 25D (see 4.4.5). Adjust
the position of the Weld -O-Let and weld neck flange, if necessary, to provide
proper orientation of the probe to the pipe. Align the probe flange boltholes
with those on the weld neck flange and verify that the flow direction arrow
stamped on the probe flange points in the proper direction.
4.4.5 For Series 25D the end support must now be positioned. Assemble the support
plug into the threaded coupling. With the Accutube properly positioned, slip
the threaded coupling over the probe tip and engage the support plug. Tack
weld the threaded coupling in place.
4.4.6 Complete the welding of the Weld-O-Let and the weld neck flange (also Thred-
O-Let in case of opposite side supported model 25D).
4.4.7 Again assemble gasket and insert probe in place observing flow arrow direction.
4.4.8 Use a flat washer with each nut and bolt. First hand-tighten each bolt. Use a
criss-cross or star pattern to tighten bolts. Check bolt tightness 24 hours after
installation.
4.4.9 The Accutube is now prepared for instrument connection and operation.
4.5 LOW PRESSURE WET TAP: SERIES 33T
4.5.1 Verify that the operating pressure and temperature are within the published limit
of the Accutube, probe valves, and mounting assembly. Refer to Table 5.
4.5.2 Prepare the pipe surface for welding and tack weld the Thred-O-Let to the pipe.
Verify alignment of the Thred-O-Let and finish the weld (see Section 4.1).
4.5.3 Assemble the support nipple (3/4” probes), chain hook and the insertion valve.
Pipe sealant/dope is recommended on all pipe threads on the mounting
assembly. Be sure that the insertion valve is in the fully open position. Be sure
the chain hook is in place between the Thred-O-Let and the insertion valve.
4.5.4 Assemble the packing gland fitting onto the valve. The fitting need only be
hand tightened and the ferrule need not be in place at this time.
4.5.5 Slide the punch through the fitting until it touches the pipe (diameter of the
guide punch must be the same diameter as the Accutube). Specially machined
punches and drills are required. These are available from Meriam.
4.5.6 Impact the punch to leave the impression on the pipe to aid in starting the drill.
4.5.7 Remove the punch and the packing gland fitting from the insertion valve.
4.5.8 Insert the drill through the insertion valve and reassemble the packing ferrule
and nut around the drill shank.
NOTE: The tapered end of the ferrule slips into the packing gland fitting body.