Neoprene EPDM Washers, Marine Grade
What are marine grade neoprene EPDM washers? These are the bonded sealing washers themselves: an EPDM rubber face bonded to a 316 stainless washer, which compresses under the fastener to seal a hole watertight. EPDM is the rubber of choice for marine and outdoor sealing because it resists weather, UV, ozone, and salt without hardening or cracking, while the 316 backing resists corrosion so the seal holds from both sides. AlbanyCountyFasteners.com stocks these with EPDM bonded to 316 stainless.
Why EPDM on 316 is the marine sealing standard
A sealing washer is only as good as its two materials, and this pairing picks both for the marine environment. The rubber has to stay soft and elastic to keep sealing, and ordinary rubbers harden, crack, and fail under sun and salt within a few seasons; EPDM resists UV, ozone, weathering, and salt, holding its elasticity far longer so the seal keeps working. The metal behind the rubber has to hold the clamp and not corrode, because a rusting backing washer streaks, weakens, and eventually breaks the seal from behind; 316 stainless resists chloride corrosion and stays sound. Bonded together, they compress into a watertight, corrosion-resistant joint that survives the exposure a marine or coastal penetration actually sees. It is the combination, elastic weatherproof rubber on a non-corroding backing, that makes it the standard choice rather than either material alone.
Why choose marine neoprene EPDM washers
- EPDM face resists UV, ozone, weather, and salt without hardening
- Stays elastic to keep sealing over years of exposure
- 316 stainless backing resists corrosion and holds the clamp
- Compresses into a watertight, corrosion-resistant joint
- Seals fastener penetrations that must not leak
Common applications
- Watertight deck and cabin penetrations
- Coastal roofing and cladding fasteners
- Dock box, hatch, and locker fixings
- Enclosure and panel seals
- Hardware through a surface that must stay dry
- Any sealed fastener hole in salt and weather
Marine Neoprene EPDM Washer FAQs
Is this EPDM or neoprene?
The sealing face is EPDM, bonded to a 316 stainless washer. EPDM is preferred for marine sealing because it resists UV, ozone, weather, and salt better than many rubbers, keeping its elasticity and seal over time.
Why bond the rubber to 316 rather than plain steel?
A plain or plated steel backing would corrode, streak, weaken, and break the seal from behind. 316 resists salt corrosion so the metal stays sound and the seal holds. Both materials are chosen for the marine environment.
How much should I compress it?
Enough to seat and seal the rubber firmly, not so much that it splits or extrudes out. Tighten until the rubber is compressed and sealing, then stop, since overtightening ruins the seal.
How long will the seal last?
EPDM's resistance to UV, ozone, and salt gives it a long service life outdoors compared with ordinary rubber, staying elastic rather than cracking. Life depends on exposure and correct installation, but it is chosen for durability.
Can I reuse one?
Once compressed the rubber takes a set and may not reseal fully, so fit new when remaking a watertight joint for a reliable seal.
Does it seal on rough surfaces?
The rubber handles minor irregularity, but a rough or damaged surface undermines any seal. Seat on sound, reasonably flat material, and add bedding compound where the surface is uneven.