Capstone: Component Inspection Walkdown
The Scenario
Unit 2 is in for a major overhaul, and the outage inspection team has compiled six findings across six different components — one from nearly every module in this track. Some are routine, expected wear that simply gets documented and trended. Others need correction before the unit can safely return to service. This module walks through each finding the way an experienced technician or engineer would, applying exactly the concepts covered in Modules 2.1 through 2.6.
The Pattern — Not Every Finding Is a Problem
A common mistake for less experienced personnel is treating every inspection finding as equally urgent. In reality, outage findings sort into distinct categories: normal, expected wear on components designed to wear (like erosion shields); minor conditions within documented engineering acceptance limits, appropriate for trending rather than repair (like a sub-threshold rotor bore indication); and active or safety-critical conditions that must be corrected before startup, regardless of cost or schedule pressure (like an under-torqued coupling bolt or active steam cutting at a joint).
The question for every finding isn't "is something wrong?" — wear and minor indications are normal in a machine that's been running for years. The real question is "does this finding fall within its component's designed tolerance, or has it crossed into territory that requires action before the next start?"
Correct-Before-Startup Findings
Three findings in this walkdown fall into this category, each for a different reason rooted in earlier modules. The horizontal joint steam cutting (Module 2.2) indicates the precision-fitted casing joint has been leaking — a condition that actively worsens the joint surface every additional hour it runs uncorrected. The bearing #3 babbitt wipe (Module 2.4) shows the bearing's intentionally sacrificial surface has already done its protective job once, but is now damaged in a way that won't reliably support the hydrodynamic oil film going forward. And the under-torqued coupling bolt (Module 2.6) is corrected without exception, because a coupling bolt failure at operating speed is a serious mechanical event — there's no acceptable trend-and-monitor path for that particular finding.
Trend, Monitor, or Fix-While-Accessible
The other three findings don't require the same urgency. The rotor bore UT indication (Module 2.1) is below documented rejection criteria — exactly the kind of minor finding that gets tracked against future inspections rather than triggering immediate repair. The LP erosion shield wear pattern (Module 2.3) is, if anything, evidence the shield is doing precisely what it was designed to do; the only real question is remaining thickness margin, not whether wear exists at all. And the gland seal clearance (Module 2.5) being above spec doesn't threaten safe operation — labyrinth seals are built around controlled leakage in the first place — but since the unit is already opened up, correcting it now while accessible is the practical, efficient call rather than waiting for the next outage.
Good outage planning depends on this kind of triage — correctly separating "must fix now" from "fine to trend" is what keeps outage scope focused on what actually matters, rather than either missing a safety-critical item or spending outage time and budget on components that are performing exactly as designed.
Bringing Track 2 Together
Every finding in this walkdown traces directly back to a specific module's core concept: rotor bore stress and creep tolerance, casing joint sealing integrity, sacrificial erosion protection, sacrificial babbitt protection, controlled labyrinth leakage, and coupling bolt criticality. That's the real payoff of understanding construction and components in depth — not memorizing part names, but being able to correctly interpret what a given finding actually means and what it requires.