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Overhaul procedure

1. Conduct a tool box meeting, risk assessment to be done
2. Make sure proper tools and spares are present. Hydraulic jacks in good working order.
3. Read the instructional manual carefully.
4. Wear proper PPE
5. Isolate the unit, 
6. Drain the cooling water, isolate the exhaust air spring supply,
7. Drain the hydraulic oil, remove the hydraulic pipes.
8. Remove necessary connections, exhaust bellow,
9. Open the hydraulic nuts using hydraulic jack, 
10. After removed, place valve on wooden platform
11. Remove the oil cylinder,
12. Release the air from non-return valve of air spring
13. Remove cot ring of spindle remove after tapping down the piston
14. Fit the oil cylinder, and hoist the cylinder to remove the valve spindle
15. Bottom housing remove, remove lock nut
16. Fit lifting tool to piston from air cylinder
17. Fit 2 eye bolts to air cylinder then remove
18. Remove the guide bush

 

Maintenance aspects:

Exhaust valve stem:

• Inspect the valve cone and its bottom surface using template
• Examine the valve seating area by means of dye-check for any crack
• Check the contact condition of valve stem with valve seat
• Inspect the valve stem for any scratch or any scoring marks
• Inspect the stem tips for any damage 

Valve seat: 

• Inspect the condition of seat and measure any abnormality by means of a template
• Inspect for any sign of cracks by means of dye check
• Examine the hot corrosion, burning or pitting

Guide bush:

• Inspect bushing for wear
• Measure the clearance of valve guide bush
• Guide bush clearance must be within limit to avoid overheating

Valve cage:

• Inspect the valve case for decreasing the thickness due to corrosion 
• Inspect and carry out pressure test for cooling water side

Oil cylinder:

• Inspect and check measurement of the bore of the cylinder
• check the wear of the piston ring
• Check the function of damper piston

Air cylinder:

• Check the running surface for wear or possible swing
• Check the piston and rod sealing ring for wear
• Inspect each and every component so that all worn and damaged parts can be identified and replaced or reconditioned

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