316 Stainless Steel Lock Washer 5/16" 100-Pack (FAS-WL316-5/16)
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316 Stainless Steel Lock Washer — 5/16", 100-Pack
Keep marine fasteners secure against vibration and movement with these 316 stainless steel split lock washers. Sized for 5/16" bolts and screws — one of the most common fastener sizes in marine hardware installations — the FAS-WL316-5/16 100-pack provides a cost-effective bulk supply of corrosion-resistant lock washers for deck hardware, engine mounts, electrical panels, and any through-bolted installation where fastener retention is critical.
Key Features
- 316 Stainless Steel — Superior corrosion resistance in salt water, bilge, and high-humidity marine environments; 316 alloy provides significantly better corrosion resistance than 304 SS in chloride-rich conditions
- Split Lock Washer Design — Helical split creates spring tension under the fastener head, biting into both the fastener and the mating surface to resist loosening under vibration and dynamic loads
- 5/16" Bolt Size — Fits 5/16" bolts, machine screws, and carriage bolts used throughout marine hardware, deck fittings, engine mounts, and electrical panel installations
- 100-Pack Bulk Quantity — Sufficient for a full hardware installation project or a well-stocked onboard and workshop spares kit
- Consistent Dimensions — Precision-stamped to consistent thickness and split geometry for reliable spring tension across the full pack
Specifications
- Material: 316 stainless steel
- Type: Split (helical) lock washer
- Bolt Size: 5/16"
- Quantity: 100 per pack
- Application: Deck hardware, engine mounts, electrical panels, through-bolted fittings, stanchion bases, cleats
- SKU: FAS-WL316-5/16
When to Use Lock Washers
- Engine mounts & motor brackets — High vibration environment; lock washers prevent backing off under continuous engine operation
- Deck hardware — Cleats, stanchion bases, handrails, and through-bolted fittings subject to load cycling and vibration
- Electrical panels & bus bars — Prevents terminal screws from loosening under vessel vibration, maintaining reliable electrical connections
- Outboard motor brackets & transom hardware — High-vibration, high-load applications where fastener retention is safety-critical
316 vs 304 Stainless — Why It Matters
316 stainless steel contains molybdenum, which significantly improves resistance to chloride-induced pitting and crevice corrosion — the primary failure mode for stainless fasteners in marine environments. Always specify 316 SS for below-waterline, deck, and engine bay applications. 304 SS is acceptable only for interior, dry applications where salt exposure is minimal.
Installation Notes
Place the lock washer between the fastener head (or nut) and the mating surface — not between the washer and the substrate. Tighten the fastener to the specified torque; the split will compress and flatten, creating the locking tension. Do not reuse lock washers that have been fully compressed — replace with new washers to ensure effective locking action. For critical applications, combine with a flat washer beneath the lock washer to protect soft substrates.
The FAS-WL316-5/16 100-pack is the right bulk supply for any marine installation where 5/16" fastener retention and corrosion resistance are required.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.