air from the dryer shall have a maximum system pressure dew point [4]
[minus 18] degrees C [40] [0] degrees F. [The Contractor shall obtain
system air for the controls by piping from the existing system.]
2.3.7
Compressor Design Features
Compressor shall be multistage centrifugal, with a minimum of 2 centrifugal
compression stages, designed for optimum flow and speed requirements to
produce highest space efficiencies at lowest compression ratio and
temperature and lowest external noise level. Special attention shall be
given to energy saving features in design and arrangement such as radial
damper intake valve, long radius interstage piping, and low air velocities.
Equipment shall be designed for economical and rapid maintenance. Casing
components bearing housings and other major parts shall be shouldered,
dowelled, or designed with other provisions to facilitate accurate
alignment or reassembly. Shaft seals and bearings shall be accessible for
inspection or replacement with a minimum of disassembly.
2.3.7.1
Casings
Casing shall be cast iron, ductile iron, or cast steel. Casing stresses
shall be within the limits allowed by ASME BPVC SEC VIII D1. Casings,
supports, and baseplates shall be designed and fabricated to preclude
excessive and injurious distortion from temperatures, pressures, and forces
encountered in service conditions, including surge. Provide jackscrews,
lifting lugs, eyebolts, guide dowels, and casing alignment dowels to
facilitate disassembly and reassembly. When using jackscrews for parting
contacting faces, relieve one of the faces by counterboring or recessing to
prevent marring the face, which result in leaking or improper fit. Provide
lifting lugs or eyebolts for removable portions of the casings. Flanged
casing connections shall conform to ASME B16.1 or ASME B16.5. Threaded
connections shall conform to ASME B1.20.1. Casing shall be split in a
manner permitting direct access to impellers, shafts, and bearings.
Compressors shall be axial flow inlet. Gear cases shall be enclosed,
accessible, force lubricated and designed with seals and slingers to keep
oil out of air system.
2.3.7.2
Shafts
Shafts shall be of forged or rolled alloy steel and shall have a machined
finish throughout their entire length. All rotating components shall be
positively secured to shafts by approved mechanical means or interference
shrink fits.
2.3.7.3
Impellers
Impellers shall be of 400 series or 17-4 PH stainless steel, open or closed
design, with backward leaning vanes, and of welded, milled, or cast
construction.
2.3.7.4
Gears
Gears shall be of alloy steel, AGMA 390.03A Quality Number 12 or better for
both bull and pinion gears. Gears shall be hardened to 275 Brinell for
bull gear and 320 Brinell for pinion, unless otherwise approved. Gears
shall be ground to the required contours, checked for proper contact during
assembly at the factory, and shall not require a break-in period in the
field for proper operation. All gears shall be pressure lubricated.
SECTION 15213N
Page 19
Previous Page
