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 3-2 for ASME
B16.5 flanges and Table 3-3 or Table 3-4 for EN flanges. Consult the factory 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 3-7 to 20% of the suggested torque values.
Repeat the process on the downstream side of the sensor. For sensors with greater or
fewer 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 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 3-7: Flange bolt torquing sequence
1
3
2
4
5
6
7
8
Prior to installation, identify the lining material of the flow sensor to ensure the suggested
torque values are applied.
Sensor Installation Reference Manual
November 2019 00809-0100-8782
18 Rosemount
®
8782 Slurry Magnetic Flow Meter Transmitter with HART Protocol
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