Power Generation

Power plant outages run to the hour. The unit is offline, the operator is losing tens of thousands of US dollars per hour for the asset being down, and the schedule is built around critical-path equipment that cannot afford to wait. Every machine choice on this page is about finishing the outage on time — not about catalogue specifications.

What the work actually looks like

Power generation maintenance breaks into three predictable patterns: water-wall and reheater tube replacement during scheduled outages, boiler header and connecting pipework repair, and turbine-side flange and valve refurbishment at the same time. Different machines, same outage window.

The constraints are also predictable: tube alloys (T22, T91, T92, P91, P92) cannot tolerate thermal cutting; the access window inside a boiler envelope is tight; and the schedule is the master variable.

Water-wall and reheater tube replacement

Water-wall panels have tubes welded to membrane bars on 50 to 100 mm centres. When a tube section is being replaced, the neighbouring tubes are still in place. That leaves a working envelope of 40 to 80 mm clearance around the work on three sides — sometimes less if a buckstay interferes.

A general-purpose split-frame beveler will not fit. The right tool is the external-clamping boiler-tube beveler: a thin annular machine that closes around the tube inside the panel pitch. Cold cutting is mandatory because the alloy tubes will not tolerate HAZ from plasma; permit-free operation is mandatory because hot-work clearance inside a boiler shrinks the productive shift in half. Full outage planning detail in boiler water-wall tube replacement.

A typical 40-joint outage with one machine has the machine as the critical path — while it is moving between joints, two welders are idle. The economics on a second machine are almost always positive.

Boiler header and connecting pipework

Heavier-wall headers and downcomers (Ø 100 to 400 mm, walls 25 to 60 mm) sit outside the panel pitch problem but inside the same metallurgy constraint. Above 25 mm wall, the V-prep that worked on the water-wall tubes is no longer the economic choice — see V vs J prep economics.

Our recommendation for header work is a split-frame OD-mount beveler with a J head for the heavier walls. The split-frame clamshell beveler covers this OD range and ships with a J tooling pack option matched to the WPS. For severing the failed section see pipe cutting machines.

Turbine, valve and heat-exchanger flange work

Turbine casing flanges, main steam valve flanges and high-pressure manifold joints typically run RTJ (ring-type joint) sealing on ASME I and Section VIII Div 1 service. When a flange face is washed by escaping steam or the groove is worn, the standard repair is in-situ refacing rather than removal.

A portable flange facer restores R, RX or BX groove geometries to API 6A tolerance — 23° wall angle ± 0.5°, Ra ≤ 1.6 µm in the groove, concentric to the bore. Full field procedure in how to machine RTJ grooves.

For heat exchangers, the tube-to-sheet joints need both faces square and the tube end perpendicular to the sheet — otherwise the expansion tool cannot land a uniform seal. Workshop bench-mount facers or the LPM electric tube facer hold the perpendicularity needed for the expansion or weld.

Why cold cutting dominates this industry

Three reasons in the order they bite a scheduler:

1. No hot-work permit inside a live envelope. Permit issuance, gas tests and fire watch add 2–4 dead hours per shift on hot work. Cold cutting removes that overhead entirely.
2. No HAZ on alloy tubes. T22 / T91 / T92 service envelopes assume the parent metallurgy is intact at the weld. Plasma cuts add 2–4 mm of HAZ that has to be milled off before welding, reversing any “speed” advantage at the cut.
3. Cleaner geometry off the machine. A milled bevel comes off inside ASME B16.25 tolerance, ready to weld. A plasma cut needs a grinder pass, and the grinder does not produce a code-tolerance face.

Full trade-off in cold cutting vs hot cutting.

What ships on a typical power outage

A working package for a mid-size thermal plant outage typically pairs:

• An external-clamping boiler-tube beveler for water-wall and reheater panel work.
• A split-frame OD-mount beveler with J tooling for header pipework.
• A portable flange facer with R / RX / BX tooling for turbine-side flange work.
• A tube facer for heat-exchanger work if the outage covers it.
• Spare insert pack matched to the alloy tube list.

For sizing against your specific outage scope and tube material list, send the spec to the quote form or talk to an engineer.