Specifications
| Item | Specification |
|---|---|
| Material | AISI 316L (UNS S31603), duplex 2205 (UNS S32205), super-duplex 2507 (UNS S32750) |
| Process | Silica sol lost wax investment casting; water glass lost wax for large rectangular sea chest bodies |
| Dimensional tolerance | ISO 8062 CT5–CT6 (silica sol); CT6–CT8 (water glass) |
| Surface finish | Ra 3.2–6.3 µm as cast; Ra 1.6–3.2 µm on machined sealing faces and basket seats |
| Machining | CNC machining of cover sealing face, basket seat, bolt circle, inlet and outlet flanges, drain and air-cock bosses |
| Weight range | 15–450 kg per piece |
| Inspection & certificates | EN 10204 3.1 mill certificate, dye penetrant testing, hydrostatic testing of the seawater side, positive material identification, dimensional report |
Key features
- Cast body with integrally cast basket seat and bosses removes the strap welds that corrode first in a seawater chest.
- Smooth as-cast flow surfaces lower pressure drop across the strainer and slow the build-up of marine growth.
- Duplex 2205 and super-duplex 2507 resist pitting and crevice attack in warm, chlorinated and low-oxygen seawater.
- CNC machined cover face and bolt circle give a repeatable gasket seal that can be opened for basket cleaning without rework.
- Drain, vent and instrument bosses are cast in place and machined to the specified thread form.
- Every body is pickled and passivated per ASTM A967, then hydrostatically tested before it leaves the works.
Applications
- Main engine and generator cooling water sea chests on workboats and tugs
- Seawater intake strainers on offshore support vessels and platform supply vessels
- Dredger pump and jet-water intake strainers handling abrasive slurry
- Ferry and ro-ro vessel cooling and ballast system sea chests
- Naval and patrol vessel seawater service strainers with shock and noise requirements
- Yacht air-conditioning, watermaker and fire pump intake strainers
Quality and compliance
We produce sea chest strainer bodies under Ningbo Ruican’s IATF 16949 certified system, with ISO 9001 documentation control for all inspection records. We supply each casting with an EN 10204 3.1 mill certificate for its heat lot, so the chemical composition and mechanical properties are traceable to the melt. Dye penetrant testing covers all machined surfaces and the as-cast waterways, and ultrasonic testing is added for wall sections above 40 mm where the drawing calls for it.
Because these bodies sit permanently on the seawater side, each strainer body is hydrostatically tested in house to the pressure stated on the drawing and the test report is shipped with the part. Moreover, pickling and passivation follow ASTM A967 with low-chloride rinsing. Classification-society witness of testing and inspection (ABS, DNV, LR, BV, ClassNK or RINA) is not a standing type approval held by Ningbo Ruican; it can be arranged on request per project, with the attendance scope and cost agreed before the order is placed.
FAQs
What pressure do you hydrostatically test a sea chest strainer body to?
Generally, the test pressure follows your drawing, normally 1.5 times the design pressure. If the drawing does not state one, we propose a value based on the class rule and the system design pressure for your approval.
Can you supply the strainer basket and cover as well?
Yes. We cast and machine the body, cover and basket frame as a matched set so the basket seat, cover face and bolt circle are machined in one alignment.
Which grade should I choose for a tropical seawater system?
AISI 316L is adequate for many temperate systems, but duplex 2205 or super-duplex 2507 is recommended for warm seawater, low flow velocity and long residence times, where pitting and crevice corrosion drive the material choice.
Do you machine the flanges to a recognised flange standard?
We machine to whatever the drawing specifies, including common marine and industrial flange patterns, and drill the bolt circle to the required hole count, pitch and spotface.
How are the castings protected during sea freight?
Machined faces get a removable rust preventive, we wrap the body in vapour-phase inhibitor paper, bagged with desiccant and crated. Additionally, the passivation layer is left intact and is not coated over.
Send your sea chest strainer drawing or sample to Wendy She — sales@cnsandcasting.com — WhatsApp +86-13777124360 for a quotation within 48 hours.
