Digester Dome Corrosion Relining
Digester dome eaten from the gas side by hydrogen sulfide rebuilt and relined against the headspace environment, no plate replacement.
What was failing
A sludge digester generates hydrogen sulfide that collects in the gas space under the dome, and where that gas meets moisture and the steel it turns into an acid that eats the dome from the inside. The attack concentrates in the headspace above the liquid line, so the crown and the upper shell lose wall while the wetted lower portion looks comparatively sound. As the steel thins, pitting opens up, perforations start, and the dome can no longer hold gas pressure or keep the process sealed. Left untreated the digester loses containment and has to come offline, which a treatment plant cannot easily afford.
How AAS approaches it
We bring the dome down to clean, profiled steel where the gas-side attack has done its work, then map the metal loss across the crown and the upper shell. We rebuild the pitted and thinned areas and any perforations with a cold-applied composite so the steel goes back to profile with no hot work in a gas-bearing vessel. Once the substrate is sound we line the whole headspace with a barrier system keyed to the hydrogen sulfide environment, sealing the original steel and the rebuilt areas under one continuous film so the acid attack has nothing left to bite into.
Assess and map
We survey the gas space to locate pitting, thinned plate, and perforations across the crown and upper shell, and confirm the headspace conditions so the lining is keyed correctly.
Surface prep
We grit-blast the affected steel to a clean, anchored profile so both the composite and the lining bond to bare metal.
Rebuild corroded steel
We rebuild pitted areas, thinned plate, and perforations with a cold-applied composite, with no hot work in the gas-bearing dome and no plate replacement.
Reline the headspace
We line the crown and upper shell with a barrier system matched to the hydrogen sulfide environment, applied over the steel and the rebuilt areas as one continuous film.
Inspect and return to service
We confirm the lining is sound and continuous and turn the dome back over for the digester to go back into service.
The result
From the job
Repair and protection work of this kind, performed by AAS crews across Louisiana.
Capabilities used here
Where this work happens
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