RCO Catalyst Inlet Distributor Inspection: Prevent Channeling Before Performance Tests

An RCO catalyst bed can be healthy while the gas reaching it is not evenly distributed. A displaced baffle, damaged perforated plate, blocked equalization path or bypass gap can create channeling. The result may look like catalyst deactivation, unstable outlet readings or an unexplained temperature profile.

This guide sets an inspection boundary for the catalyst inlet distributor before a performance test or major troubleshooting decision. It separates verified observations from assumptions and gives the plant team a repeatable evidence pack.

What the inlet distributor is expected to do

The distributor should spread the process stream across the catalyst face, tolerate the design temperature, and preserve clearances during thermal cycles. Confirm the approved drawing, flow direction, access points and any specified inspection tolerances before judging field condition.

Inspection sequence before opening the bed

1. Lock out the RCO and verify zero-energy state, cooldown and atmospheric controls under the site procedure.
2. Record recent operating cases: airflow, inlet temperature, VOC trend, pressure drop and damper positions.
3. Photograph access covers, expansion joints and visible hot spots before removing hardware.
4. Compare the installed arrangement with the latest approved drawing and change record.

Field checks on plates, baffles and supports

Inspect for warping, cracking, detached welds, erosion, deposits and foreign material. Check that perforations or slots are open and that no gasket, insulation fragment or loose fastener can migrate toward the catalyst. Measure distortion only with calibrated tools and record the reference points.

Evidence that points to channeling

Channeling becomes more credible when several independent clues agree: localized deposit patterns, asymmetric discoloration, a change in pressure drop without a matching airflow change, or repeatable outlet differences by operating case. A single thermocouple excursion is not proof. Correlate observations with flow, temperature and maintenance history.

Repair and release decisions

Define whether the issue is cleanable, adjustable or a replacement scope. The work pack should state who owns refractory removal, welding, NDE, gasket replacement and debris clearance. After repair, document torque or weld records as applicable, close all foreign-material controls and repeat the same operating case used for comparison.

Questions to ask an RCO supplier

Ask for the distributor material and temperature basis, allowable distortion criteria, inspection access limits, recommended NDE, and the evidence required to accept a repaired boundary. Request assumptions in writing when the original design record is incomplete.

FAQ

Can channeling be confirmed from outlet VOC data alone?

No. Outlet data can trigger an investigation, but confirmation requires a boundary inspection and correlation with airflow, temperature and configuration evidence.

Should the catalyst be replaced first?

Not automatically. Prove the inlet-distribution path, measurement validity and operating case before assigning the cause to catalyst activity.

What is the minimum handover package?

At minimum: marked-up drawing, dated photographs, condition measurements, repair records, foreign-material clearance and a repeatable post-work operating record.

Plan the next inspection with SERNO

SERNO can help structure an RCO inspection scope around your actual access, operating history and evidence requirements. Share the available drawings and trend records to define a reviewable work pack; no performance claim is implied until site data is verified.