Bolt tightening method

Bolt tightening method

Non torque ring wrench or hammering wrench: suitable for general equipment and pipeline flange tightening, selected according to bolt size and flange pressure rating. The fastening requirements are as follows:

1) The maintenance unit shall develop a fastening plan, symmetrically fasten the flanges, and number them in the fastening sequence, referring to Figure 1 and Figure 2 for numbering

2) Use 4 bolts as washers at positions 1, 2, 3, and 4 for positioning, and confirm that the center of the wrapped washer is within the edge of the flange

3) Tighten the positioning bolt by hand, then insert other bolts and tighten them by hand to balance the load. Confirm that at least 2 threads are exposed on each end of the nut

4) Based on the on-site equipment and flanges, calculate the number of tightening cycles (at least 3 times) and the impact load (force) for each tightening cycle. Tighten the impact load (force) in ascending order from small to large (such as 50%, 80%, 90% increasing), and do not apply too fast or too large a load to prevent gasket sealing failure

5) The sequence of tightening each time with a torque free plum blossom wrench or impact wrench:

Tighten the two radially opposite bolts to the predetermined hammering load (force) of the bolts

Tighten another pair of bolts that are approximately 90 degrees apart along the circumference from the previous two bolts

Continue tightening until all other bolts are tightened to the predetermined hammering load

6) Then tighten all bolts in a clockwise or counterclockwise direction with a hammer load (force) of 90%