Page 243 - Reciprocating Compressors Operation Maintenance

228 Reciprocating Compressors: Operation and Maintenance

b, Aluminum bearing shells
.001" -.0015" per inch of journal diameter

Crosshead pin to crosshead bushing clearance:
.0005"-.0015" per inch of pin diameter
Crosshead pin to crosshead clearance:
.0005"~.002" per inch of pin diameter

Crosshead to crosshead guide clearance:
.00075"-.Q01" per inch of crosshead diameter

Piston ring end gap:
cast iron -.003" per inch of cylinder diameter
carbon -.003" "
bronze -.004" "
Teflon® -.024" "
phenolic -.005" "
Piston ring side clearances (average):
cast iron -.003" to .004" per inch of ring width
carbon -.003" "
bronze -.004" "
Teflon® -.010" "
phenolic -.015" "

Minimum clearance between rider ring and cylinder bore in middle of
piston adjacent to piston rings:

cast iron piston ~.00125"-.OQ15" per inch of cylinder diameter
aluminum piston -.002" per inch of cylinder diameter

fi = .000006" per inch per degree F
(coefficient of expansion of cast iron or steel)
Example: Crosshead to crosshead guide clearance:
Crosshead diameter - 8M"
At = 75°F (ambient) to 170°F = 95°F
AL = (.000006) (95) (8.5) x 1.2 = .006"