March 2016
12
Quick Start Guide
4.2 Flange bolts
Note
Do not bolt one side at a time. Tighten both sides simultaneously. Example:
1. Snug upstream.
2. Snug downstream.
3. Tighten upstream.
4. Tighten downstream.
Do not snug and tighten the upstream side and then snug and tighten the downstream side.
Failure to alternate between the upstream and downstream flanges when tightening bolts may
result in liner damage.
Suggested torque values by sensor line size and liner type are listed in Table 4 for
ASME B16.5 flanges, Table 5 for EN flanges, and Table 6 and Table 7 for AWWA
and EN flanges for line sizes 30-in. (750 mm) to 48-in. (1300 mm). Consult your
local Emerson
™
Process Management representative if the flange rating of the
sensor is not listed. Tighten flange bolts on the upstream side of the sensor in the
incremental sequence shown in Figure 11 to 20 percent of the suggested torque
values. Repeat the process on the downstream side of the sensor. For sensors
with more or less flange bolts, tighten the bolts in a similar crosswise sequence.
Repeat this entire tightening sequence at 40, 60, 80, and 100% of the suggested
torque values.
If leakage occurs at the suggested torque values, the bolts can be tightened in
additional 10% increments until the joint stops leaking, or until the measured
torque value reaches the maximum torque value of the bolts. Practical
consideration for the integrity of the liner often leads the user to distinct torque
values to stop leakage due to the unique combinations of flanges, bolts, gaskets,
and sensor liner material.
Check for leaks at the flanges after tightening the bolts. Failure to use the correct
tightening methods can result in severe damage. While under pressure, sensor
materials may deform over time and require a second tightening 24 hours after
the initial installation.
Figure 11. Flange Bolt Torquing Sequence
Prior to installation, identify the lining material of the flow sensor to ensure the
suggested torque values are applied.
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