PetroStreet

In your experience, carbonic acid corrosion prevention and mitigation should include using corrosion inhibitors or without that?
Please let me know if you need more details to facilitate your inputs.

Yes, corrosion inhibitors should be considered as one of the primary mitigation methods for carbonic acid corrosion—but not automatically in every system. Whether they are necessary depends on the process conditions, materials of construction, and whether other mitigation measures alone can achieve the required corrosion control.

From my perspective, the first question I would ask is whether the process can be engineered to avoid significant carbonic acid corrosion in the first place. Corrosion inhibitors are often highly effective, but they are generally considered an operational mitigation measure rather than the first design solution.

They may not be required if the system remains completely dry (no aqueous phase) or a corrosion-resistant alloy provides sufficient protection.
Also if process conditions inherently result in negligible corrosion rates or internal polymer lining or non-metallic piping provides adequate resistance.

See as per API 570, for CO2 corrosion, following preventions /mitigations can be applied:

a) Corrosion inhibitors can reduce CO2 corrosion in steam condensate systems. Vapor phase inhibitors may be
required to protect against condensing steam.
b) Increasing condensate pH above 6 can reduce corrosion in steam condensate systems.
c) 300 series SS are highly resistant to CO2 corrosion in most applications. 400 series SS and duplex stainless
steel are also resistant.
d) Selective upgrading to stainless steel is usually required in operating units designed to produce and/or
remove CO2 (i.e. hydrogen plants and CO2 removal units). Selecting a stainless steel to mitigate CO2
corrosion in any operating unit needs to account for other potential damage mechanisms applicable to the
specific environment.
e) CO2 corrosion in steam condensate systems can often be managed by correcting or improving the operating
conditions and/or water treatment program.
f) Ensure insulation and jacketing are in good condition to prevent unexpected and undesired cooling, which
could lead to condensation and resultant CO2 corrosion.
g) Internal coatings can be effective where the design and environment permit.

And that all starts with corrosion inhibitor in steam condensate systems.
And second with pH control of condensate.

Moving on, (c) says that 300 series SS are highly resistant and they can be used if the affected area is other than the steam condensate systems like overhead systems in regenerators in CO2 removal processes.

But depends what is the affected equipment in your case?