What plant conditions accelerate under-deposit corrosion the fastest in exchangers and piping?
Please provide some insights to capture all those conditions.
Under Deposit Corrosion Propagation
Re: Under Deposit Corrosion Propagation
The biggest contributors here are low flow /stagnation conditions.
When flow velocity drops solids settle, water pockets accumulate, sludge forms, heat transfer surfaces foul, corrosion inhibitors stop reaching surfaces effectively.
Typical scenarios include dead legs, standby exchangers, low-rate circulation loops, oversized piping, bypass lines, seasonal low throughput, intermittent operation, horizontal piping with low velocity and similar scenarios where above conditions can occur.
High-risk areas where we can actually spot and look for UDC include bottom of horizontal lines, exchanger channel heads, tube inlets, low points, reboilers, and quench systems.
When flow velocity drops solids settle, water pockets accumulate, sludge forms, heat transfer surfaces foul, corrosion inhibitors stop reaching surfaces effectively.
Typical scenarios include dead legs, standby exchangers, low-rate circulation loops, oversized piping, bypass lines, seasonal low throughput, intermittent operation, horizontal piping with low velocity and similar scenarios where above conditions can occur.
High-risk areas where we can actually spot and look for UDC include bottom of horizontal lines, exchanger channel heads, tube inlets, low points, reboilers, and quench systems.
Re: Under Deposit Corrosion Propagation
We have been discussing to get these conditions defined within IOW program to make sure there is no uDC happening.
Minimum velocity, water dewpoint margins, salt deposition temperatures, and fouling tedency play important role here.
Otherwise, it stays a reactive finding upon inspection that there is uDC.
Minimum velocity, water dewpoint margins, salt deposition temperatures, and fouling tedency play important role here.
Otherwise, it stays a reactive finding upon inspection that there is uDC.
Re: Under Deposit Corrosion Propagation
I would support this idea and need to check if we have any such parameter defined in our IOWs.
Once this is in place, monitored, and reported, we are covered in identifying UDC.
Scenarios have been very well covered by mechcolor.
Once this is in place, monitored, and reported, we are covered in identifying UDC.
Scenarios have been very well covered by mechcolor.
novice123 wrote: 30 May 2026, 10:05 We have been discussing to get these conditions defined within IOW program to make sure there is no uDC happening.
Minimum velocity, water dewpoint margins, salt deposition temperatures, and fouling tedency play important role here.
Otherwise, it stays a reactive finding upon inspection that there is uDC.
Re: Under Deposit Corrosion Propagation
The fastest UDC damage usually occurs when MULTIPLE factors overlap simultaneously like there are deposits present, intermittent water, low flow/stagnation, oxygen ingress, chloride concentration, transient operations etc.
That combination can produce extremely rapid localized attack even while bulk chemistry looks acceptable, average corrosion rates look low, and process conditions appear all good.
If you have already identified some cases where the damage has occurred and you do not have any parameters defined to observe, you start defining them today to avoid any uncalled for and unidentified UDC, localized in nature.
That combination can produce extremely rapid localized attack even while bulk chemistry looks acceptable, average corrosion rates look low, and process conditions appear all good.
If you have already identified some cases where the damage has occurred and you do not have any parameters defined to observe, you start defining them today to avoid any uncalled for and unidentified UDC, localized in nature.