Maintenance Guide

NAB Valve Maintenance & Care Guide: Maximize Service Life

Published on March 13, 2026 | By Supreme Valves India

Proper maintenance is essential for maximizing the service life of Nickel Aluminum Bronze (NAB/NiAlBr) valves in marine and offshore applications. This guide covers storage, installation, inspection, and maintenance best practices.

Proper Storage Procedures

Before Installation

Store valves in a clean, dry environment
Keep valves in original packaging until installation
Protect from dust, moisture, and contaminants
Avoid stacking heavy items on valve boxes
Store butterfly valves in FULLY OPEN or FULLY CLOSED position

Long-Term Storage

Apply preservative oil to external surfaces
Use desiccants in packaging for humidity control
Inspect periodically (every 3-6 months)
Cycle valves annually to prevent stem seizure

Installation Best Practices

Before Installation

Inspect valve for shipping damage
Verify identification tag matches specifications
Check that the valve is clean inside
Ensure pipe ends are also clean

During Installation

Support pipe weight to prevent stress on valve
Use proper gasket materials (non-asbestos recommended)
Do not use valve as a lever for pipe alignment
Tighten bolts evenly in a cross-pattern
Do not exceed recommended torque values
Install strainers upstream of control valves

Routine Inspection Schedule

Frequency	Inspection Items
Monthly	Visual inspection, leak check, operation test
Quarterly	Bonnet bolting torque, gland packing, stem condition
Annually	Full disassembly, seat inspection, replacement of worn parts
Every 5 Years	Major overhaul, pressure testing, wall thickness check

Common Issues and Solutions

Stem Leakage

Cause: Worn or hardened packing
Solution: Replace packing; adjust gland follower

Difficulty in Operation

Cause: Stem corrosion, mineral deposits, or dried lubricant
Solution: Apply penetrating oil; cycle valve slowly

Body/Flange Leakage

Cause: Improper gasket, uneven bolt tension, flange damage
Solution: Replace gasket; re-torque bolts evenly; inspect flange face

Reduced Flow/Blockage

Cause: Biofouling, sediment buildup, or internal corrosion
Solution: Clean internals; install upstream strainer; consider more frequent cycling

Maintenance Checklist

□ Visual inspection for corrosion or damage
□ Check for external leaks at body and stem
□ Verify handle/gear operation is smooth
□ Inspect gland packing condition
□ Check bolting for corrosion or loosening
□ Verify position indicator is accurate
□ Test emergency shutoff function
□ Document inspection findings

When to Replace

Consider valve replacement when:

Wall thickness below minimum required (typically 3mm minimum)
Severe external corrosion affecting structural integrity
Stem is damaged or worn beyond repair
Seat leakage cannot be stopped by normal maintenance
Valve has exceeded design life (typically 20-25 years for seawater service)

Conclusion

With proper maintenance, NAB valves can provide 20+ years of reliable service in marine and seawater applications. Regular inspection, prompt repairs, and following these guidelines will maximize your valve investment and prevent costly unplanned downtime.

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