CSCase study · Fabrication
Ladle and trunnionoverhaul.
01The brief
A 300 t ladle back in service before the spring campaign
The client's basic-oxygen shop ran three ladles. One had cracked trunnion bosses, and the reline slot was fixed: miss it and the shop would run on two ladles through the summer.
We took the ladle shell in on a heavy-haul trailer, cut out both trunnion assemblies and replaced them with new forged trunnions and cast bosses from our own melt shop. The shell was stress relieved in one piece in our largest furnace before final machining.
02What we did
Four processes, one dossier
- Poured two 4.2 t trunnion bosses in G20Mn5, simulated to avoid shrinkage at the bore
- Forged two trunnion pins in 34CrNiMo6 with a 4:1 reduction and full UT
- Welded bosses into the shell to an EXC3 procedure with a numbered weld map
- Stress relieved the full shell at 580 °C and line-bored both trunnions in one set-up
14wksFrom arrival to hot commissioning
0NCRsRaised at final inspection
62tOf new cast and forged steel
“We got the ladle back two days before the reline slot, with one folder that covered every weld, every heat and every hardness reading.”
RVR. VerbeekMaintenance manager, steel shop
