A4 Stainless Steel R-Clips (Hairpin Cotter Pins) are supplied to Trade series (hairpin cotter). The grade provides superior, including marine and chloride environments and is largely non-magnetic; the practical service range is approx. -200 °C to +400 °C, subject to the property class and the joint. Property data, grade comparison and the full size table follow.
Why Choose A4 Stainless Steel for R-Clips (Hairpin Cotter Pins)
Specified for marine, coastal and chemical applications. For r-clips (hairpin cotter pins), this matters when superior, including marine and chloride environments is the primary requirement.
Mechanical & Physical Properties
| Grade designation | ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80 |
|---|---|
| Magnetic response | Largely non-magnetic |
| Service temperature | approx. -200 °C to +400 °C, subject to the property class and the joint |
| Corrosion characteristic | Superior, including marine and chloride environments |
Corrosion Behavior in Service
A4 (316) adds 2–3% molybdenum to the A2 (304) composition, which dramatically improves resistance to chloride-pitting corrosion. For R-Clips (Hairpin Cotter Pins) in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.
Galvanic & Galling Considerations
For stainless r-clips (hairpin cotter pins) the compatibility question is galvanic rather than galling: joined to aluminum or galvanized steel in wet service, stainless drives corrosion of the less-noble metal. Isolate with a coating, sleeve or non-conductive washer where the joint sees moisture. Note also that stainless is softer than hardened carbon steel, so where the part carries a wear or shear duty, check the load against the grade before substituting.
Using Stainless Fasteners in Aluminum
Stainless steel is more noble than aluminum, so with an electrolyte present — rain, condensation, salt spray — the aluminum becomes the anode and corrodes at the joint. Area ratio decides how bad it gets: a small stainless fastener in a large aluminum section is normally acceptable, a large stainless fastener in thin aluminum is not. Where the joint gets wet, isolate the metals with a coated or nylon washer and a sealant, or specify an aluminum or coated fastener instead.
Sizes of R-Clips (Hairpin Cotter Pins) Available in A4 Stainless Steel
| For pin diameter (mm) | Wire diameter (mm) | Usable length (mm) | Overall length (mm) | Fits cross hole (mm) | Material | Finish | Re-use |
|---|---|---|---|---|---|---|---|
| 5 | 1.6 | 30 | 40 | 2.0 | Spring steel | Zinc plated | Yes, if not sprung |
| 6 | 2.0 | 40 | 52 | 2.5 | Spring steel | Zinc plated | Yes, if not sprung |
| 8 | 2.5 | 50 | 65 | 3.0 | Spring steel | Zinc plated | Yes, if not sprung |
| 10 | 3.0 | 60 | 80 | 3.5 | Spring steel | Zinc plated | Yes, if not sprung |
| 13 | 4.0 | 80 | 105 | 4.5 | Spring steel | Zinc plated | Yes, if not sprung |
| 16 | 5.0 | 100 | 130 | 5.5 | Spring steel | Zinc plated | Yes, if not sprung |
