Application Guides

Boiler Waterwall Spray-Application Checklist

Use this checklist to coordinate the boiler outage, waterwall condition survey, surface-preparation acceptance, spray access, shadow-zone checks, layer records, curing and return-to-service release. Project specifications and approved application instructions remain controlling.

Scope, isolation, and shutdown handover

Confirm the exact panel, elevation and work boundary before access is released. Record isolation status, ventilation, lighting, access equipment, nearby work and the conditions that must be maintained during preparation, application and cure.

Identify the responsible handover and release roles.
Mark exclusions, repairs and interfaces with adjacent systems.
Confirm safe access to front, side and transition areas.
Protect accepted work from concurrent dust, moisture and hot work.

Pre-cleaning condition survey

Photograph and map the as-found condition before deposits and loose material are removed. Keep the location references consistent through all later inspection records.

Tube, membrane, weld, and attachment zones

Record directional wear, deposits, pits and prior repairs.
Inspect weld toes, membrane transitions, clips and penetrations.
Identify rear or side areas that need special access.

Damage requiring engineering escalation

Escalate cracks, bulging, leakage, uncertain wall loss, unstable repairs or any condition outside the approved protection scope. Do not use coating work to conceal a defect that requires boiler or structural assessment.

Surface-preparation acceptance gate

Define the required preparation and inspection evidence from the project specification. Verify representative front, side, rear and transition surfaces; remove residues; and confirm that prepared areas remain protected from flash rust, condensation and recontamination.

Record the preparation method and accepted work zone.
Check difficult geometry with suitable lighting and access aids.
Close defects and nonconformities before material application.
Confirm environmental and substrate conditions at release.

Access and spray-sequence plan

Divide the waterwall into traceable work zones. Define application direction and overlap so tube curvature, membrane valleys, welds and attachments are approached from the necessary angles without contaminating previously accepted areas.

Demonstrate access and spray reach on representative geometry.
Sequence upper, lower and adjacent work to control fallout and overspray.
Keep hoses, scaffolding and movement away from uncured surfaces.
Maintain clear boundaries between completed and pending zones.

Shadow-zone and transition coverage checks

Inspect the locations most likely to be missed: tube sides, membrane valleys, rear quadrants where accessible, weld transitions, attachments and work-zone boundaries. Do not accept the panel solely from its front-face appearance.

Layer-by-layer inspection and records

Record material identity, batch, preparation release, application zone, environmental observations, layer sequence, nonconformities and repairs according to the approved procedure. Distinguish wet application observations, intermediate acceptance and final cure evidence.

Verify continuity before the next layer closes access.
Use only the measurement methods required by the project.
Trace repair records to the same zone map.
Retain representative photographs with dates and locations.

Cure, repair, and return-to-service release

Protect the completed work for the specified cure and inspect it before access systems are removed. Reprepare and repair defects using the approved procedure, repeat the affected inspection step, and release the waterwall only when required records and outstanding items are closed.

Checklist limits and project-specific instructions

This checklist supports field planning but does not set product-specific mixing, film build, temperature, cure time or return-to-service conditions. Use the approved product documents and project method statement for those values.