| Fault | Possible Cause | |
|---|---|---|
| a | Lapping | Pouring too slow Metal not hot enough |
| b | Tube outer dia. rough | Protrusion of pouring bucket spout in bore beyond the end plate of mould |
| c | Slag/oxide bands produced | Inadequate deoxidizing agent in ladle |
| d | Bore tube oxidization | Temperature of metal too low Mould temperature too low Crucible/pouring bucket temperature too low Furnace and casting pouring into mould delayed |
| e | Rough tube surface at spray end | Mould not cool enough Spinning time of mould insufficient to cool mould |
| f | Tube surface dimpled often at center | Low spin speed Pressure of spray tank too high Low metal temperature Consistency of mould wash too smooth |
| g | Tube length incomplete or tapered tube wall | Mould contains refractory material, possibly from pouring bucket or furnace Pouring bucket or spout requires maintenance |
| h | Spray end showing isolated patches of slag | Belling at either or both ends of tube. Check dimensions of mould Check coating Check mould temperature |
| i | Casting difficult to remove | Belling at either or both ends of tube. Check dimensions of mould Check coating Check mould temperature |
| j | Tube surface inconsistent (a spiral appearance may be produced) | Inadequate mould coating in tank Spray cone nozzle worn or restricted Coating Slurry too thin |
| k | Large diameter tubes longitudinal cracks in casting | Tube run on at high speed for too long after casting |
| l | Surface of tube covered with pin holes, especially pronounced at spray end | Low metal temperature Oil traces in airline (faulty filter) |
| m | Cracking/tearing fracture around circumference | Contraction of tube restricted Mould wash left in mould, inadequate cleaning Belling - refer to item (i). |
| n | Patches of slag deposits on spray end of tube | Metal deposits requires cleaning at furnace and/or ladle |
| o | Pin-holing in patches and/or condensation | Lance dripping with spray or craters at spray end Lance sloping downwards |
| p | Molten metal raining in mould | Molten metal temperature too high Speed to slow |
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