A4 Stainless Steel Fully-Threaded Standoff Caps are supplied to our own published dimensions — this is a trade-series article rather than one covered by a dimensional standard, so confirm the figures against the part you are replacing. 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.
Why Choose A4 Stainless Steel for Fully-Threaded Standoff Caps
Specified for marine, coastal and chemical applications. For fully-threaded standoff caps, 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 |
Galvanic & Galling Considerations
Two important notes for stainless fully-threaded standoff caps: (1) stainless can gall on stainless threads under load — use a thread lubricant or anti-galling compound, especially for M6 and below; (2) when joined to aluminum or galvanized steel, stainless can drive galvanic corrosion of the less-noble metal in wet service — isolate with a coating or sleeve where appropriate.
Comparable Grades
For Fully-Threaded Standoff Caps, the alternative stainless grade is A2 (304). Choose A2 (304) for general use and A4 (316) wherever chlorides are present; the molybdenum in A4 is the whole difference. Remember that stainless is the corrosion answer, not the strength answer — for load, look at class 8.8 or 10.9 instead.
Using Stainless Fasteners in Aluminum
The galvanic couple here runs the wrong way: aluminum is the less noble metal, so it corrodes and the fastener does not. What governs the rate is the ratio of areas — a large anode and a small cathode is a tolerable combination, the reverse concentrates the attack into thin material around the hole. An isolating washer plus sealant breaks the circuit; where that is impractical, match the fastener to the substrate.
Sizes of Fully-Threaded Standoff Caps Available in A4 Stainless Steel
| Thread size | Outside diameter (in) | Cap height (in) | Thread length (in) | Form |
|---|---|---|---|---|
| 4-40 | 1/4 | 1/4 | 3/8 | fully threaded cap |
| 6-32 | 1/4 | 1/4 | 3/8 | fully threaded cap |
| 8-32 | 1/4 | 1/4 | 3/8 | fully threaded cap |
| 10-32 | 1/4 | 1/4 | 3/8 | fully threaded cap |
Dimensions are independent of the material: the table above lists the sizes supplied, and on this page every one of them is quoted in A4 Stainless Steel. The catalogue's default material column has been omitted here so it cannot be read as contradicting that.
Custom manufacturing · Made to drawing
Need this standoff & spacer in a grade that is not listed?
A4 Stainless Steel is one of the grades the catalog describes. Dimensions, material, finish and form are specified from the drawing — a standoff & spacer outside the standard range is a variation on existing tooling rather than a new design. Made by tapping or turning.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
