Quick question from the crew: every so often a 150×150 billet whistles on the runout table after stand 5, usually around 900–950°C. I was taught it’s steam from scale water hitting longitudinal checks, but we also end up tracing it to a loose entry guide or a tired table roller bearing about 1 in 5 times — do you treat that whistle as a safety/maintenance alarm or just harmless noise at your mill?
We treat it as a soft alarm: feather the descaler about 10% or kick the air-wipe — if the whistle dies, it’s steam; if the pitch climbs with line speed, it’s a guide or roller bearing (“if the pitch chases speed, it’s a bearing”). I’ll ping @maintenance if it persists two heats in a row; a quick strobe/tach on the suspect table roller has nailed the culprit more than once — otherwise it’s just a tea‑kettle at 920°C.
At about 930°C, quick IR check: one roller +20°C = bearing; else ‘steam’, @d_smith83.
And i nudge the looper — if the whistle shifts with tension, it’s steam; otherwise check entry-guide liner wear, @d_smith83.
I treat it as a heads-up, but my first poke is a per-side spray toggle on the runout: bump the left, then right header for 2–3 s — if one side kills the “kettle” note, it’s splash/scale; if not I start hunting a guide or a noisy roller. We once chased this for a shift and it was a tiny scale dam at the stripper bar splashing back under the 150, not a bearing, @jason_smith89.
I blip line speed ±5% and listen — if the pitch tracks speed it’s boil‑off, but if it holds or you hear a beat I put a mechanic’s stethoscope on the entry‑guide or that table roller and it tells on itself. One caveat: a dribbling apron can fake the note, so flip the apron off for one billet to confirm, @rolldoc. Kinda like tuning a guitar, except the string’s a 150×150 at 930°C.
At 950°C mine peaked over the drain trench; clogged grate jetting steam — clear it, @n_harper22.
Had the same whistle after stand 5 and it turned out a hairline leak at the side‑spray strainer gasket was pulling air — the header whistled worse around “900–950°C”, @n_harper22, and it drove me nuts. Crack the vent plug on that header for 1–2 s; if the note dies it’s air entrainment, otherwise bump the pan weir one hole to break a steam tunnel before chasing bearings.