Series B Class 400 Flanges

Series B Class 400 flanges provide an intermediate pressure rating between Class 300 and Class 600 in the lighter API 605 pattern. Like other Class 400 flanges, they fill a specific niche for systems that marginally exceed Class 300 working pressure limits without requiring the full weight and cost of Class 600 components.

The combination of Class 400 pressure rating with the Series B weight reduction makes these flanges particularly attractive for offshore and marine applications where topside weight is a critical design constraint. Every pound saved on flanged connections contributes to reduced structural steel requirements and lower platform construction costs.

Availability of Series B Class 400 flanges may be more limited than Class 150 or 300, as this is a less commonly ordered combination. Extended lead times should be anticipated, and early procurement is recommended for projects requiring multiple flanges in this specification.