Bolting Requirements; Bolt/Fastener Tightening - GE H301 Series Operating Manual

bolting Requirements

The packager is responsible for locating and drilling the bolt holes in the fabricated
compressor pedestal. The drilled holes should not be less than .875" (22.225 mm)
nor more than 1.0" (25.4 mm) diameter to allow for minor hole location variances
in the pedestal and frame. A hardened steel .75" (19.05 mm) washer is required
under the head of each .75" (19.05 mm) diameter anchor bolt. The packager is
responsible for providing a fabricated pedestal to allow bolt length that should not
be less than 10 times the bolt diameter of .75" (19.05 mm) to maintain bolt stretch
when properly torqued. Therefore, the packager should have a steel spacer
totaling 7.5" (190.5 mm) to allow for a capscrew length 8.75" (222.25 mm). The
8.75" (222.25 mm) capscrew provides for the 7.5" (190.5 mm) stretch length plus
1.25" (31.75 mm) thread engagement into the frame.
3. The compressor frame's hold down bolt is typically .125" (3.175 mm) smaller in
diameter than the mounting foot hole opening, unless otherwise specified.
4. The length of hold down bolting should be as long as possible and stressed
using a torque value appropriate with the bolting material.
5. "Table 14" lists the minimum frame foot and crosshead guide bolt sizes and
torque requirements.
6. Use of the tabled values is based upon bolting materials with proof loads
greater than 100,000 Psi (689,480 kpa). Higher strength bolting material is
preferred.
7. Compressor frame foot bolting typically uses ASTM A193 B-7 threaded studs
or Grade 8 bolts, along with hardened steel washers and ASTM A194 nuts.
8. Use Grade 8 or 9 bolts for all compressor mounting points.
9. Verify the hold down bolt torque value, 'soft foot' deflection, and proper
crosshead guide support shimming at initial compressor startup and quarterly
during the compressor's normal operation.
Compressor
Hole diameter
model
Inch (mm)
H302 .875 (22.225)
Hold down bolting torque range
Table 14

bolt/Fastener Tightening

Follow these instructions to tighten the bolts/fasteners.
1. Clean the fastening hardware threads and contact surfaces. Keep them free of
burrs or dings. This includes bolt, stud and nut threads, washer, nut, bolt head
and associated contact surfaces.
2. Install threaded fasteners with minimal hand force.
3. Torque values are based upon petroleum lubricated threads and seating
surfaces. Use SAE 40 weight oil.
4. Install fasteners with some radial clearance. Avoid placing the fastener
threads in shear or loaded against the fastener's opening in the mounting foot
or skid.
5. Use a calibrated torque wrench, and a torque multiplier, as required.
Frame foot
Recommended
Foot-pound (N-m)
bolt or stud size
(Inch – TPI)
Min.
.75-10 -UNC 225 (305)
Torque range
Max.
250 (340)
H301/302 HSR Compressors | Rev. 2.2 | 47