Flowserve Nordstrom Dynamic Balance Plug Valve and Double DB Plug Valve - Manual (Page 29)

Flow Control
Nordstrom Valves
FCD NVENIM2005-01 Dynamic Balance ® Plug Valve and Double DB ® Double Isolation Plug Valve 29
8 Procedure for Tightening
Cap Screws and Nuts
NOTE: This procedure is intended only as a guide. It is impossible
for Flowserve to anticipate all field-site conditions, so rely on your
own judgment and experience.
1. Inspect applicable parts to be sure that:
a. Tapped holes are clean, dry, and free of foreign matter.
b. Threads are free of nicks, grit, and burrs.
2. Apply a quality thread lubricant on the threads of the Cap
Screws/Nuts, or the tapped holes, and the contact face of the
Cap Screws/Nuts.
3. Install all Cap Screws/Nuts by hand. Engage the threads at least
1/2 of the diameter before using a wrench.
4. To avoid cocking the parts, hand-tighten the first four Cap
Screws/Nuts in the sequence shown in Figure 12.
Tighten the first four Cap Screws/Nuts in the sequence shown in
Figure 12.Tighten them only to 1/2 of the torque value shown in
Table 2 or 3 in the Technical Data section.
5. Tighten the remaining Cap Screws/Nuts to 1/2 of the torque value
shown in Table 2 or 3. Use the crisscross pattern shown in
Step 2.
6. Repeat Steps 5 and 6, tightening the Cap Screws/Nuts to the full
torque value, as shown in Table 2 or 3.
7. Re-check the torque on the first four Cap Screws/Nuts. If the
torque is less than the minimum shown in Table 2 or 3, tighten
them to the full torque. Re-check the torque on the remaining
Cap Screws/Nuts until they are all within the specified torque
range.
Figure 12 – Bolt-tightening patterns










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Step 1 (1st Value)
Snug to approximately 10% of specified torque.
Sequence: Any
Step 2 (2nd Value)
Torque to approximately 75% of specified torque.
Sequence:
4 Bolt: 1-2-3-4
6 Bolt: 1-2-3-4-5-6
8 Bolt: 1-2-3-4-5-6-7-8
Step 3 (3rd Value)
Torque to specified torque.
Sequence: Same as in Step 2.
NOTE: The method shown above for tightening the Cover Bolting
is for the purpose of pulling the Cover down evenly. If this can be
achieved without precisely following the suggested method, some
variation is permissible.