This document outlines the standard operating procedures (SOP) for air compressor maintenance at Petronet LNG Ltd. It describes the three types of preventative maintenance: 3-monthly PM, 6-monthly PM, and 12-monthly or overhaul PM. The SOPs detail the steps to be followed for each type of maintenance, including ensuring safety isolations, inspecting and replacing parts as needed, checking clearances, lubricating, and testing operation upon completion. The goal is to contribute to effective equipment functioning and maintain quality and consistency in work.

1. SOP FOR AIR COMPRESSORS
PETRONET LNG LTD
RAKESH NIMBALKAR

2.  SOP – Standard Operating Procedure
 Need– To contribute to the effective functioning of the
task & to maintain quality & consistency in work.
 Types:
a) 3 Monthly PM
b) 6 Monthly PM
c) 12 Monthly PM or OVERHAUL

3. 3 MONTHLY PM
 Ensure electrical isolation.
 Take work permit and confirm that all precautions and isolations
mentioned in the permit are actually done.
 Remove of all instrument air tubing for L.P. (Low pressure) & H.P. (High
pressure) suction valves.
 Remove/check the condition of the valves L.P. & H.P.), service or
replace parts/ assembly if necessary.
 Clean suction valve unloaders.
 Clean suction/discharge valve holder for both L.P. & H.P.
 Check/ clean air filters, replace if necessary.
 Assemble the valves in the cylinders. Check compressor foundation
bolts tightness.
 Check belt condition, replace if necessary & check belt tension.
 Clean the work area and dispose waste materials (metallic scrap,
cotton waste) to bins to avoid land contamination.
 Close work permit & release electrical isolation.
 Take trial run; check for leakages attend if any

4. 6 MONTHLY PM
 Ensure electrical isolation.
 Take work permit and confirm that all precautions and isolations mentioned in
the permit are actually done.
 Remove of all instrument air tubing for L.P. (Low pressure) & H.P. (High
pressure) suction valves.
 Remove/check the condition of the valves (L.P. & H.P.), service or replace
parts/assembly if necessary.
 Clean suction/discharge valve holder for both L.P. & H.P. Clean suction valve
unloaders.
 Remove cylinder end cover; check (wedge) clearance between piston and
cylinder (L.P. & H.P.).
 Check cylinder (L.P. & H.P.) end clearances.
------Note the clearance between the crosshead shoe & guide.
 Remove piston of L.P. & H.P if wedge clearance is not within limits.
 Check the condition of piston rings and rider (wear) rings.
 Dismantle piston assembly L.P. /H.P. if piston/rider (wear) rings to be changed.
 Change piston/rider rings.
 Assemble the piston assembly with new piston/rider (wear) rings.
 Check any abnormality in the cylinders by the way of visual inspection.

5.  -----Remove the crosshead
 ----Check for the presence of any shim between the crosshead shoe &
crosshead, remove the shim if any present
 ----- Check for the tightness of countersunk bolts
 -----Install the crosshead
 Assemble the piston in cylinders (L.P. & H.P.). Take cylinder end clearances
& wedge clearance.
 ------Tighten the locknut by holding the piston rod with the help of spanner
so that the tightening force is not transmitted to deflecting the cross head
position.
 -----Place two 0.15 mm shims between the crosshead guide & shoe on
either ends so that a uniform clearance is maintained between the shoe &
guide.
 ------Lock the washer on to the locking nut & crosshead

6.  Check the lube oil condition, replace if necessary.
 Check / clean lube oil filters, replace if necessary.
 Check/ clean air filters, replace if necessary.
 Assemble the valves in the cylinders.
 Check compressor foundation bolts tightness.
 Check belt condition, replace if necessary & check belt tension with belt
tension-meter.
 Clean the work area and dispose waste materials (metallic scrap, cotton
waste) to bins to avoid land contamination, waste/used lube oil to store to
avoid land contamination & slippage of personnel.
 Close work permit & release electrical isolation.
 Take trial run; check for leakages attend if any.

7. 12 MONTH PM (OVERHAUL)
 Ensure electrical isolation.
 Take work permit and confirm that all precautions and isolations mentioned
in the permit are actually done.
 Remove of all unloader assembly air tubing for L.P. (Low pressure) & H.P.
(High pressure) suction valves.
 Remove/check the condition of the valves (L.P. & H.P.), service or replace
parts/assembly if necessary.
 Clean suction/discharge valve holder for both L.P. & H.P. Clean suction
valve unloaders.
 Remove cylinder end cover; check (wedge) clearance between piston and
cylinder (L.P. & H.P.).
 Check cylinder (L.P. & H.P.) end clearances.
------Note the clearance between the crosshead shoe & guide.
 Remove piston of L.P. & H.P if wedge clearance is not within limits.
 Check the condition of piston rings and rider (wear) rings.
 Dismantle piston assembly L.P. /H.P. if piston/rider (wear) rings to be
changed.
 Change piston/rider rings.
 Assemble the piston assembly with new piston/rider (wear) rings.
 Check any abnormality in the cylinders by the way of visual inspection

8.  Check cross head clearances, gaudgeon pin clearances (L.P. & H.P.).
 -----Remove the crosshead
 ----Check for the presence of any shim between the crosshead shoe &
crosshead, remove the shim if any present
 ----- Check for the tightness of countersunk bolts
 Check main bearing clearance, replace if required with proper torque. Note
final clearances.
 Remove connecting rod, check small end/ big end bearing clearances,
replace the bearings if required with proper torque. Note final clearances.
 Drain crankcase oil and renew with fresh oil.
 Check / clean lube oil filters, replace if necessary.
 -----Install the crosshead

9.  Assemble the piston in cylinders (L.P. & H.P.). Take cylinder end
clearances/wedge clearance.
 ------Tighten the locknut by holding the piston rod with the help of spanner
so that the tightening force is not transmitted on to deflecting the cross
head position.
 -----Place two 0.15 mm shims between the crosshead guide & shoe on
either ends so that a uniform clearance is maintained between the shoe &
guide.
 ------Lock the washer on to the locking nut & crosshead

10.  Check pressure packings/oil packings, replace if necessary.
 Check/ clean air filters, replace if necessary.
 Assemble the valves in the cylinders.
 Check compressor foundation bolts tightness.
 Check belt condition, replace if necessary & check belt tension with belt
tension-meter.
 Clean the work area and dispose waste materials (metallic scrap, cotton
waste) to bins, used/waste lube oil to store to avoid land contamination &
slippage of personnel.
 Close work permit & release electrical isolation.
 Take trial run; check for leakages attend if any.

11. THANK YOU