Introduction: When a converter mouth is worn and the original drawing is gone, the part itself becomes the main record of the shape a replacement has to match.
Older BOF vessels often outlive their paperwork. A maintenance learner then faces a very practical problem: the mouth ring is burned, cracked and built up with slag, no dimension sheet survives in the plant archive, and a replacement still has to bolt on cleanly and last the next campaign. The useful path is not guesswork. A worn part carries readable information — where it mated, where it ran hottest, where slag flowed, where it distorted — and that reading, combined with notes on how the vessel actually works, is what turns a damaged casting into a defined replacement shape.
The converter mouth is the open end of the vessel, the place where off-gas leaves and where the vessel tilts to charge scrap and tap steel, as steelmaking course material describes when it covers vessel structure and mouth operation. That position explains why the mouth part accumulates such a visible history. Slag that ran over the lip leaves a directional wear step. Thermal cycling leaves a family of cracks instead of a single one. Maintenance welds show where earlier crews tried to buy time. None of this is a drawing, but all of it points to which surfaces must mate and which sections must stay thick. A learner reading a worn part should look for four kinds of evidence before any measuring starts. The first is the mouth opening: diameter and taper control how the lip sits relative to the hood and the lance above it, and ovality tells you the part has crept under heat. The second is the outer fixing band where the ring meets the vessel shell. The third is the repair record written on the surface in weld beads and grinding marks. The fourth is the slag pattern, which shows where molten material preferred to run and pool, and therefore where the replacement cannot afford to lose section thickness. Reading these first means later measurements land on the features that matter instead of the ones that are easiest to reach.
Numbers alone give a set of dimensions. Geometry comes from deciding which of those dimensions control the fit and how much material the replacement needs to survive the same duty. Four features carry most of that judgment, and they are best read in order.
Read together, those four features turn a copy into a design. Copying a worn outline simply reproduces whatever distortion the old part ended its life with. Reviewing the same outline against working conditions lets the replacement cast back to clean geometry, with extra material placed only where the duty demands it. That single shift is what separates converter mouth replacement parts that fit from those that need cutting and welding on site.
Reverse measurement produces a point cloud or a set of hand dimensions, and it stops paying off the moment it is asked to answer questions that belong to casting practice and furnace operation. A worn part can show where a section thinned, but the thickness of the new casting is set by feeding, gating and how heavy sections solidify — not by the worn profile. Resin sand and lost foam casting behave differently on thick sections and on complex outlines, and the foundry chooses the process around the shape and its tonnage rather than around the copy. Engineering review takes the measured shape and reads it against the working conditions: how many heats the vessel runs per campaign, what slag practice the plant follows, what the hood and lance arrangement expects of the mouth edge, and which material grade the plant specification names. Grades such as QT400-18, EN-GJS-400-18, Gr60-40-18 and FCE 400-18 describe broadly the same ductile iron family in different national systems, so the drawing or the plant standard decides which name applies to the order. Shape, size and material are all customised to the converter design, which is why this step ends with a casting definition rather than a duplicated outline. Some details stay on the plant side by design. Internal water passage geometry, non-destructive testing acceptance levels and the dimensional tolerance class come from furnace design documents and the plant's own quality specification, and a competent water cooled converter mouth manufacturer will ask for them rather than assume them. Delivery timing follows the same project-by-project pattern. That is the natural handover point: observation and measurement describe the old part, and the engineering review turns the description into a new custom BOF lip ring casting that a heavy foundry can actually pour, machine and fit.
A missing drawing is a paperwork problem, not a dead end. The worn mouth tells you where it mated, where it ran hottest, where slag cut deepest and where it crept out of shape; those features, read in sequence, define the surfaces and sections a replacement has to respect. Engineering review then adds what the worn part cannot say on its own: casting practice, grade selection and the plant's own tolerance and testing requirements. Anyone comparing notes with a water cooling converter mouth supplier gets further by bringing wear marks, slag patterns and working-condition notes than by bringing a photograph alone. The product reference for this kind of part is worth a look once those notes are in hand.
A: It reveals the mating band where the ring meets the vessel shell, the bolt pattern and the condition of the bosses, the taper and roundness of the mouth opening, and the direction of slag flow written into the worn surfaces. Repair welds and crack networks add a service history. Together these describe which surfaces must fit and which sections must stay thick, which is the practical starting point for a replacement.
A: The mating face sets the datum, so it is restored to a true plane and everything else is built back from it. Bolt areas fix the hole pattern and show where extra material around bosses helps. Heat-affected zones and slag wear marks show where sections should be thicker and where the grade must tolerate repeated heating and cooling. Each mark becomes a shaping decision rather than a dimension to copy.
A: Photos are a useful first input because they show crack patterns, weld repairs, slag build-up and obvious distortion. A casting shape also needs measured mating faces, bolt positions, opening taper and notes on the working conditions the part has to survive. Photos start the reading; measurement and engineering review turn it into a casting definition that can be poured and fitted.
NPTEL: Steelmaking Technology and Converter Operations
Iron and Steel Production - EU-BRITE
