Lifecycle Cost Analysis for Coating System Selection, Stainless Steel Vent Stack

Competing Objectives

The project brought two objectives into direct conflict. The developer wanted the vent stack to be visually consistent with the surrounding streetscape, favouring a coated finish. The asset owner’s priority was a low-maintenance asset over a 50-year design life, which favoured minimising coating maintenance obligations, particularly at height, where recoating access is costly. RemedyAP’s lifecycle cost analysis was commissioned to resolve this with an evidence-based recommendation rather than a preference-led decision.

Corrosivity Assessment

The stack sits in a C2, general atmospheric corrosivity environment for the majority of its 28-metre height. At the vent tip, however, exposure to hydrogen sulphide gas venting from the sewer network raises the local corrosivity category to C4, a materially more aggressive environment than the rest of the structure experiences. This meant a single coating recommendation could not be made for the whole asset without accounting for the different exposure conditions at each end.

Lifecycle Cost Analysis and Recommendation

RemedyAP modelled lifecycle cost across four coating systems, acrylic latex, polyurethane, polysiloxane, and fluoropolymer, against the 50-year design life and the asset’s corrosion resistance requirements.

Because the stainless steel substrate does not require a coating for corrosion protection, and given the aggressive local environment at the vent tip, the recommendation was that the vent tip itself be excluded from paint application altogether. A drip line was specified between segments 6 and 7 to manage water runoff and prevent staining from tracking down the stack onto the coated sections below. On the lifecycle cost comparison, the final recommendation favoured either acrylic latex or fluoropolymer for the coated sections, with the choice between the two coming down to the asset owner’s maintenance preference: acrylic latex offering a lower upfront cost with a shorter maintenance intervals, and fluoropolymer offering a longer service interval at a higher initial cost.

Outcome

The recommendation gave the asset owner a coating strategy that met the developer’s aesthetic requirement on the visible sections of the stack, while avoiding an unnecessary and high-maintenance coating specification at the vent tip, where the substrate’s inherent corrosion resistance and the aggressive local environment made coating counter-productive. The drip line detail addressed a practical maintenance issue, staining, that a coating specification alone would not have resolved.

Why RemedyAP for Coating System Lifecycle Cost Analysis

Coating system selection is often decided on upfront cost or aesthetic preference alone, without accounting for how corrosivity varies across a single asset, or what that means for whole-of-life maintenance cost. RemedyAP’s lifecycle cost analysis brings corrosivity assessment and coating system comparison together, so asset owners and developers can make a coating decision based on the asset’s actual exposure conditions and the project’s real maintenance priorities, not just the initial specification cost.

Conclusion

This case study shows how a lifecycle cost analysis resolved a coating specification conflict between a developer’s aesthetic goal and an asset owner’s maintenance priority, using corrosivity assessment and a like-for-like comparison of four coating systems against a 50-year design life. The result balanced both objectives, rather than defaulting to a single blanket coating specification across the whole asset.

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