Ball Valves for Marine & Offshore

Vajra Industrial Solutions' marine ball valve designs carry product design approvals from DNV GL (Det Norske Veritas Germanischer Lloyd), Lloyd's Register, Bureau Veritas, and ABS (American Bureau of Shipping) for the most common marine materials and pressure ratings. Approvals cover: naval brass (C95800) and SS 316L ball valves in DN15–DN200, PN10–PN25, for fire main, bilge, general service, and seawater cooling duty; duplex 2205 ball valves in DN15–DN600, Class 150–600, for offshore topsides and ballast water treatment. For a specific vessel class society (NK, RINA, ClassNK), or for non-standard materials (titanium, super duplex), contact Vajra with project details — additional documentation packages can be prepared and submitted for society review. Lead times for class society review are typically 4–8 weeks and should be factored into project schedules.

Standard SS 316L (CF3M) is marginal for seawater service above 20°C. SS 316L has a PREN (Pitting Resistance Equivalent Number) of approximately 23–26, which is below the minimum 35 recommended for sustained seawater service at ambient tropical temperatures. In cold seawater (North Sea, Baltic, below 15°C), SS 316L may be acceptable for intermittent seawater contact; however, for continuous seawater service, pump suction and cooling lines, class societies typically require PREN ≥ 35 (duplex 2205 minimum) or copper alloy (naval brass) materials. SS 316L is acceptable for: potable water and sanitary systems aboard ship (not seawater); low-salinity ballast water at cold temperatures; instrument and sampling lines with very low seawater exposure. For any seawater cooling, sea chest, or ballast water main — specify duplex 2205 or naval brass.

NORSOK M-630 is the Norwegian Oil Industry standard governing material selection and qualification for offshore equipment exposed to North Sea corrosive environments. It specifies Material Data Sheets (MDS) that define minimum alloy requirements, heat treatment, testing, and documentation for each valve application. Key requirements: duplex 2205 valves for seawater service require MDS D45 or D46 with specific PREN, Charpy impact, and corrosion testing; all PMI (positive material identification) results must be documented; heat treatment records must match the MDS requirements. NORSOK M-630 is mandatory on projects specified by Equinor (Statoil), Aker BP, ConocoPhillips Norway, and on UKCS (North Sea) projects aligned with Norwegian standards. Specify NORSOK M-630 requirements on the purchase order with the applicable MDS numbers — Vajra's quality team will ensure full compliance documentation in the valve data book.