NIBCO Iron Gate Valves - Manual (Page 9)

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9
APPENDIX I
Body to Bonnet Bolt Installation Procedure for
NIBCO Cast Iron, Alloy Iron and Ductile Iron Valves
The following procedure outlines the methods to be used in the assembly of and field installation
of the body to bonnet bolts and nuts in order to assure the proper clamping stresses. The
correct sequence and torque for tightening the body to bonnet bolts and nuts is also identified.
These instructions apply for ASTM A307 Grade B high tensile strength bolting material used on
NIBCO cast iron, alloy iron, and ductile iron valve body and bonnet flange joints.
1. Visually inspect all threads and remove all foreign matter such as rust, dirt, corrosion
and any lubricant.
2. Clean the body gasket and bonnet gasket seating area thoroughly.
The gasket seating area must be clean prior to assembly as the area becomes
inaccessible after assembly. The area is to be cleaned with a suitable solvent or
cleanser that can remove all dirt, grime and gasket particles.
3. The threads of the bolts and the surfaces under the bolt heads and nuts to be coated
with an anti-seize compound such as Felpro, type C5A Hi-Temp Anti-seize compound or
equal. The threads of the nuts should also be lubricated. Clean off excess lubricant with
solvent as noted in Item 2.
NOTE: Resilient-Wedge Gate Valves use only socket head cap screws to attach bonnet
to body, no nuts.
4. Clean off the gasket. Make sure that no foreign particles are stuck to it that might cause
a leak. Make sure the gasket is the correct size. It should fit inside the bonnet-body bolt
holes.
5. Place the bonnet in position; insert the bolts and hand tighten the nuts against the body.
A minimum of 2-1/2 threads should extend beyond each nut.
6. After the nuts are hand tight, follow the tightening sequence shown in the table. The
sequence shown is an illustrated method only, and the actual sequence is dependent
upon the total number of bolts.
7. The use of an air impact device which does not have a direct torque control is prohibited
for the torquing of body to bonnet bolts. The use of a hand torque wrench, electronic
torquing system, or power wrench with direct torque control is recommended. If such
equipment is not available, the following standard wrenches may be used:
1/2” bolts 6” wrench
5/8” bolts 12” wrench
3/4” bolts 18” wrench
7/8” bolts 24” wrench
1” bolts 36” wrench