825 Piece Grade 18.8 Stainless Steel Hex Head Cap Screw, Nut, and Washer Assortment Starter Kit
When the environment is the problem — marine exposure, outdoor installation, food service, or chemical contact — 18.8 stainless is the right call. This 825-piece assortment covers 1/4" through 3/8" stainless cap screw diameters in a labeled 24-hole metal drawer, purpose-built for applications where carbon steel would corrode.
What's Included
- 18.8 stainless steel hex head cap screws — 1/4"-20, 5/16"-18, and 3/8"-16, multiple lengths per size
- 18.8 stainless hex nuts — matching every bolt size
- Stainless flat washers and lock washers — one set per diameter
- 24-hole metal drawer — QR-coded labeled and ready to stock
- 825 pieces total
Specifications
| Thread standard | UNC — Unified National Coarse |
| Material | 18.8 Stainless Steel (AISI 304) |
| Tensile strength | Approx. 70,000–85,000 PSI |
| Finish | Mill finish (passivated stainless) |
| Diameters | 1/4"-20, 5/16"-18, 3/8"-16 |
| Total pieces | 825 |
| Approx. weight | 24 lbs |
| SKU | ASST24SS188 |
Best For
- Marine and boating applications — saltwater environments that would corrode carbon steel in weeks
- Outdoor installations — signage, fencing, enclosures, and structural hardware exposed to rain and humidity
- Food service and processing equipment — FDA-compatible material that won't contaminate food-contact surfaces
- Chemical and industrial environments — equipment exposed to cleaning agents, solvents, or corrosive atmospheres
- Automotive restoration — visible engine bay hardware and exterior trim where appearance matters as much as corrosion resistance
About 18.8 Stainless Steel
18.8 refers to the alloy composition: 18% chromium and 8% nickel (AISI 304). The chromium forms a passive oxide layer on the surface that prevents rust — even without a plating or coating. Unlike zinc-plated carbon steel, the corrosion resistance of 18.8 stainless doesn't wear off over time or with scratches.
The tradeoff is tensile strength. At 70,000–85,000 PSI, 18.8 stainless is not a high-strength fastener — it's below Grade 5 and well below Grade 8. Use it where corrosion resistance is the primary requirement, not strength. For high-strength corrosion-resistant applications (like marine structural work), specify 316 stainless or Grade B8 instead.
Note on galling: Stainless steel fasteners can gall (seize) when threading into stainless nuts at high torque. Apply an anti-seize lubricant when assembling stainless-to-stainless joints to prevent this.
For carbon steel assortments with plated corrosion resistance, see our Grade 8 UNC and Grade 8 UNF kits.
Shipping & Ordering
- Ships within 1–2 business days from our warehouse
- Volume pricing available — save up to 20% when ordering 3 or more kits
- B2B accounts: Marine contractors, food service equipment shops, and facilities teams can apply for a business account with custom pricing and a dedicated rep — contact us to get started