Six months. Three replacements. Same leak.
In a thermal power plant, maintenance engineer Arvind finally traced the problem: not pressure, not alignment, not torque surface finish. A tiny imperfection on the valve seat was letting high-pressure steam slip through.
Sealing isn’t about force. It’s about finish.
At IPC Valves, we’ve built that into everything we do.
1. Lapping = Real Sealing
The seal isn’t when “metal touches metal.” It’s when there’s no space left not for steam, gas, or even a film of process fluid. In metal-seated Gate, Globe, and Check valves, sealing quality depends on the precision of contact between disc/wedge and seat.
Mirror-lapped surfaces = zero micro-gaps = leak-tight shutoff + longer life.
2. What Is Lapping (In Plain Terms)?
Lapping is an ultra-fine finishing step where the disc (or wedge) and seat are polished together using abrasive media. It removes microscopic high spots, tool marks, and distortion.
Lapped surfaces deliver:
- Tight shutoff / near-zero leakage
- Lower wear over time
Reliable sealing at temperature & pressure extremes
3. Why It’s Essential in Metal-Seated Valves
In service, trim components slide, wedge, or land directly on the seat. Tiny ridges = leak paths. Mis-matched geometry = accelerated wear.
Lapping matches the contact geometry. Result: stable sealing stress, less scuffing, fewer early rebuilds.
4. How IPC Laps for Performance (Not Just Spec)
Many plants assume “machined = good enough.” We don’t. At IPC, we do not cut corners to save time or cost. We finish to sealing performance, not just drawing tolerance.
Manual Precision Lapping (Custom / Critical Repair)
- Surfaces blued (dye transfer check)
- Disc worked against seat with graded abrasives
- Repeated until 100% contact pattern
Automated / Machine Lapping (Production Consistency)
- Controlled pressure, rotation, and stroke
- Uniform finish across multiple parts
Repeatable Ra values batch after batch
5. Abrasives We Use (Matched to Job)
Silicon Carbide (SiC) – Faster stock removal on hard alloys.
Diamond Paste (sub-micron to ~5 µm) – Ultra-fine final polish for mirror finish and tight shutoff.
(Other media used as material demands; selection driven by metallurgy + seal class.)
6. Where the Lapping Happens (Trim Contact Zones)
Gate Valve: Tapered wedge faces to seat rings.
Globe Valve: Disc face (flat or slightly convex) to top of seat ring.
Swing Check Valve: Disc seating edge to inner seat face.
Clear knowledge of the actual contact band is key to correct lapping.
7. Higher-Output, High-Accuracy Solutions
IPC also deploys or supports portable and multi-head precision valve lappers for large-seat and in-line refurbishment:
- Simultaneous multi-seat lapping
- Ra ≤ ~0.3–0.4 µm achievable
- Reduced operator fatigue
Faster turnaround on outage-critical jobs
8. The Invisible Step That Saves Plants Crores
Lapping never makes the spec sheet headline but it shows up in:
- Fewer unplanned shutdowns
- Lower leak rates (energy & media savings)
- Longer mean time between rebuilds
Stable performance under cycling
Every IPC metal-seated valve is finished for sealing integrity you can trust.
Because when the pressure builds, finish is everything and ours shines.