Seawater Resistant O-Rings
Compatibility ratings for 7 O-ring materials in Seawater service
Seawater (General) compatibility with the seven most common O-ring elastomers, rated on the standard A/B/C/D scale: A = excellent, B = good, C = fair, D = not recommended. This data also appears in our interactive chemical compatibility chart and is available machine-readable at /api/chemicals.json.
| Material | Rating | Guidance |
|---|---|---|
| NBR | B | good — suitable for most applications |
| FKM | A | excellent — recommended for continuous service |
| EPDM | A | excellent — recommended for continuous service |
| VMQ | B | good — suitable for most applications |
| PTFE | A | excellent — recommended for continuous service |
| FFKM | A | excellent — recommended for continuous service |
| HNBR | B | good — suitable for most applications |
Why These Ratings
- EPDM (A) — documented strengths include “Hot water and steam.”
- PTFE (A) — documented strengths include “Steam and hot water.”
- FFKM (A) — documented strengths include “Steam (grade dependent).”
GeneralService: Concentration & Temperature Notes
Water looks simple, but the details matter: temperature and certifications (FDA, NSF 61, WRAS) drive selection more than chemical survival. Our seawater row shows the chloride effect — NBR and VMQ drop from A (fresh water) to B while FKM holds A. Hot water and steam are different service entirely; check the steam guidance on the individual material pages.
Recommended
- FKM O-rings (A)
- EPDM O-rings (A)
- PTFE O-rings (A)
- FFKM O-rings (A)
Use With Caution
- NBR O-rings (B)
- VMQ O-rings (B)
- HNBR O-rings (B)
Avoid
No material is rated D for this chemical.
Related Guides
Related Chemicals (General)
Frequently Asked Questions
Is Seawater compatible with FKM (Viton) O-rings?
FKM is rated A for Seawater: excellent — recommended for continuous service. Ratings are general guidelines; concentration, temperature and exposure time all affect real-world compatibility, so validate critical applications with ASTM D471 immersion testing.
Is Seawater compatible with NBR (nitrile) O-rings?
NBR is rated B for Seawater: good — suitable for most applications. NBR is the lowest-cost elastomer, so when it earns an A or B rating it is usually the economical default; when it rates C or D, do not substitute it for a higher-rated material to save cost.
Can I use PTFE O-rings with Seawater?
PTFE is rated A for Seawater: excellent — recommended for continuous service. Remember that PTFE has no elastic memory — in demanding service it needs spring energization or an elastomer core (FEP/PFA encapsulation) to maintain sealing force.
What is the best O-ring material for Seawater?
FKM, EPDM, PTFE, FFKM are rated A (excellent) for Seawater in our compatibility data and are the recommended starting point for material selection. Final selection should also account for operating temperature, pressure and whether the seal is static or dynamic.
Can I use EPDM O-rings with Seawater?
EPDM is rated A for Seawater: excellent — recommended for continuous service. Always confirm the specific fluid concentration and temperature before specifying EPDM for this service.
Need O-Rings for Seawater Service?
Send us your fluid, concentration and temperature — our engineers will confirm the right compound. MOQ 1 piece.