Technical Bulletin 106
Notes regarding corrosion of solenoid valves used in seawater applications.
- Hydracon submersible solenoid valves are produced using a combination of materials. The solenoids are made of two types of stainless steels, 316 (non-magnetic) and 400 series (magnetic). Valves bodies and glands are usually made using 316 cres steel. The spool (often also serving as the armature for the solenoid) is made of 400 series magnetic stainless steel, also highly corrosion resistant. Usually, hardware, such as screws, nuts and lockwashers, are grades of 300 series or 18-8 stainless steels. Underwater connectors are 316 SS. Other materials available by request.
- Seawater is an electrically conductive fluid. Metals of unlike grades, immersed in seawater, develop EMF voltage, as in a battery, resulting in corrosion of the metals.
- Forms of marine corrosion:
dealloying, corrosion cracking.
- Seawater corrosivity factors:
- Metallic parts, such as tubing, fittings, and the surrounding structure will be involved in the galvanic process.
- Dissolved minerals may become coated to metals. Close fitting parts, such as threads, are subject to mineral deposition, making disassembly difficult. Screw threads should be packed with marine grease.
- Valves should be flushed with fresh water, disassembled and re-conditioned after seawater service.