Dimensional tolerances for ceramic-lined equipment

Begin with what must fit, flow, move, seal or be removed. In a pipe spool, the finished bore, flange face, bolt access and transition at the mating end may govern. In a chute, clearance to gates, sensors, liners and inspection doors may matter more than overall external dimensions. In a cyclone or custom piece, concentricity and internal profile can affect assembly and process path. Create a characteristic list that names each requirement, its datum, stage of inspection and consequence if missed. This prevents a general note such as ‘dimensions to drawing’ from overlooking the few interfaces that can stop installation or create a wear ledge.

A dimension on bare fabrication, cleaned steel and finished ceramic describes three different states. Mark which state the requirement controls and allow for the approved construction without simply subtracting a nominal lining thickness from every side. Curvature, adhesive layer, joints, local repairs and manufacturing variation affect the actual result. Use datums that can be recovered after lining, or transfer them in a documented manner before they disappear. Record instrument suitability and access limitations. Where direct measurement is impossible after completion, define an earlier hold point or an approved indirect check instead of leaving the characteristic unverified.

Measure critical sections and interfaces, not only an average thickness or a single centre point. A local inward step at a flange, repair boundary or neighbouring spool can disturb flow, catch solids and expose an edge even when the mean bore is acceptable. An outward recess may also create recirculation or a pocket. Capture clock position or grid coordinate with each reading and inspect the transition profile. Check that gaskets, fasteners, instruments and removable parts still have their required seating and clearance. Any proposed field grinding, cutting or filling must preserve ceramic support, pressure or structural requirements and the approved lining detail.

Joint width, fill profile, edge alignment and cut-piece geometry can influence process exposure and future repair even when they are not traditional equipment dimensions. Around nozzles, manways and sensors, verify both clearance and a supported termination. At changes of plane, check that the intended overlap or meeting detail was achieved without a fragile sliver. Use representative sampling only where the specification permits it and increase examination around transitions or observed variation. Photographs should be tied to measured locations. A visually regular tile field can still contain a critical narrow joint, proud edge or inaccessible fastener that the dimensional record needs to reveal.

The final package should contain the characteristic list, marked drawings, measurement results, instrument references, photographs, accepted deviations and corrective work. Report actual values where useful rather than only pass or fail. When a result falls outside requirement, identify the responsible review and written disposition; do not silently widen the tolerance after fabrication. Update the as-built geometry after approved correction and retain the previous reading for traceability. These records support fit-up, commissioning and later wear analysis. They also prevent a future change in pressure, clearance or flow from being attributed to the lining without knowing its original finished geometry.