18-8 Stainless Steel Thinwall Half Hex Low Profile Head Rivet Nuts

Why this is the specification for critical joints

Because it removes both things that go wrong with a rivet nut over a long service life. Spin-out is the immediate failure, and the hex body eliminates it outright rather than reducing the probability. Corrosion is the slow one, and it is worse than it looks: the insert body fills the hole and the head clamps against the panel, so moisture that gets in cannot dry out and cannot be inspected. A plated insert corrodes there invisibly until the joint fails or the bolt seizes. Stainless with a hex body addresses both at once, which is why it costs more and why it belongs in joints that are torqued to specification and expected to be serviced years later.

Why choose 18-8 stainless half hex rivet nuts

• Hex body gives positive anti-rotation that friction cannot match
• Substantially higher load capacity than aluminum at the same thread
• Corrosion resistance in marine, washdown, and road salt service
• Low profile head minimises installed height
• Thinwall body sets reliably in sheet metal
• Correct galvanic match for steel and stainless panels

Inch sizes and grip ranges

• #10-32, 0.435 inch length, 0.020 to 0.130 inch grip
• 1/4-20, 0.585 inch length, 0.027 to 0.165 inch grip
• 5/16-18, 0.685 inch length, 0.027 to 0.150 inch grip
• Requires a hex hole matched to the body across-flats dimension
• Measure panel thickness against the grip range before ordering

Common applications

• Production chassis and frame assembly in steel
• Marine equipment and hardware torqued to specification
• Trailer and transport equipment exposed to road salt
• Washdown and food processing equipment
• Machinery guards and covers serviced repeatedly
• Any joint where spin-out or corrosion would be costly to fix

For metric threads, see our metric stainless half hex rivet nuts. On aluminum panels, aluminum half hex inserts avoid a galvanic couple.

Related Categories

• Low Profile Head Half Hex Rivet Nuts
• Aluminum Half Hex Rivet Nuts
• Half Hex Rivet Nuts
• Ribbed / Knurled Rivet Nuts
• Rivet Tools

18-8 Stainless Half Hex Rivet Nut FAQs

Are these harder to set than aluminum?

Yes, stainless requires considerably more pulling force. At 5/16-18 a basic hand tool becomes difficult, so a ratcheting or pneudraulic rivet nut tool is worth having for anything beyond a few inserts.

What hex hole dimension do I need?

Matched to the body across-flats, which is specified per insert size and much larger than the thread. Order the punch to that dimension, and confirm before buying since punches are size specific.

Can I use these in an aluminum panel?

In dry conditions yes, but stainless against aluminum with moisture present corrodes the panel around every hole. For aluminum outdoors, use the aluminum version.

Do the hex flats have to be perfect?

They need to be close enough that the insert seats without excessive play. A sloppy hex hole allows some rotation before the flats engage, which defeats part of the purpose. A proper punch gives consistent results.

How much torque will these take?

Torque resistance is limited by the panel material rather than the insert, since the hex is keyed into the panel. In sound steel sheet, they take considerably more than any friction-based insert.

Is 18-8 suitable for marine use?

For above waterline marine work, yes. It handles salt air, spray, and washdown well. For constant immersion or heavy chloride exposure, 316 would offer better pitting resistance.