A234 Grade-by-Service Selector

Map your service temperature and medium to the right A234 buttweld fitting grade — from carbon WPB up the chrome-moly ladder.

A234 WPB is a moderate-temperature carbon-steel grade (typical ceiling ~425°C / 800°F) with only moderate corrosion resistance. Above that, step up the chrome-moly ladder (WP11 to WP22 to WP91). For sour, chloride or acidic service, carbon steel is not suitable by default — confirm NACE MR0175 / ISO 15156 or move to a corrosion-resistant alloy. Guidance only; the design engineer sets the final grade against the governing code.