Marine and Shipbuilding
Seawater is the reference difficult environment: chlorides at concentration, biological fouling that creates crevices, and temperature swings that accelerate everything. 316L is not adequate for sustained warm seawater immersion despite being widely misapplied there. Super duplex and 6-Moly grades are the correct specification, and PREN above 40 is the usual acceptance threshold.
What gets specified in marine & shipbuilding
Ordered by how commonly they are called for in this sector.
- UNS S31803 / S32205 / S32550 / S32750 / S32760Duplex / Super DuplexPREN 41
Roughly equal austenite and ferrite. Around twice the yield strength of 316L.
- UNS S31254254 SMOPREN 43
6% molybdenum super-austenitic with nitrogen. PREN above 42.
- UNS S31600 / S31603316 / 316LPREN 25
304 plus 2–3% molybdenum. The standard answer to chlorides and mild acids.
- UNS N08904904LPREN 35
High nickel, high molybdenum, with copper. Built for sulphuric acid service.
Applications
06- Seawater cooling and ballast systems
- Chemical tanker cargo lines
- Propeller shafts and stern gear
- Deck fittings and rigging hardware
- Desalination plant
- Firewater systems
Governing standards
04- ASTM A790
- ASTM A928
- NORSOK M-630
- ASTM A276
Verification available
10- Spectrometer
- Chemical Testing Laboratory
- Positive Material Identification (PMI)
- Spectro Test
- Tensile Testing Machine
- Hardness Testing Machine
- Portable Hardness Tester
- Flattening Test
- Reverse-Bend Test
- Hydrostatic Test Machine
What marine & shipbuilding buys
Other industries
Supplying into marine & shipbuilding?
Send the specification and service conditions. We will confirm the grade, the availability and the documentation you will need.