Annular nail
An annular nail (ring-shank nail) has a series of rings formed around its shank that lock into the wood fibers and resist pull-out. Annular nails are generally recommended for softwoods and low-density hardwoods, and are common in block pallets.
Also called ring shank nail, annularly threaded nail, ring nail
Reviewed
How annular nails are specified
Annular nails share the standard fastener fields (length, wire diameter, head diameter, thread length and crest diameter, MIBANT) plus a ring count. In the Uniform Standard's withdrawal formula, annular threads use a factor of 60 against 22 for helical threads, reflecting how the rings grip.
Where they are used
- Softwood pallets: southern yellow pine, SPF and similar species hold rings well
- Low-density hardwoods: such as poplar and basswood
- Block pallets: a typical wood block pallet uses 3 in annular nails through the stringerboard into the block and 2-1/4 in annular nails on the bottom deck
Annular vs helical
| Annular | Helical | |
|---|---|---|
| Thread | rings | spiral |
| Usually recommended for | softwoods, low-density hardwoods | medium and high-density hardwoods |
| Behavior when driven | goes straight in | rotates |
Both easily beat the Uniform Standard minimum fastener withdrawal characteristic that a plain-shank nail cannot meet. See pallet nails.
Questions
- Are ring-shank nails good for pallets?
- Yes, especially in softwoods and low-density hardwoods, where the rings grip the fibers well.
Related
- Helical nailA helical nail has a spiral thread on its shank that turns as it is driven, resisting pull-out. It is the standard pallet nail for medium and dense hardwoods.
- Plain-shank nailA plain-shank (smooth) nail has no threads and a withdrawal characteristic of 1.0, so pallets mainly use smooth nails as clinched deck-mat nails.
- Pallet nails: types, sizes and how manyPallet nails are usually 2 to 3 in helical or annular threaded nails, 11 to 12-1/2 gauge. A GMA 48 x 40 uses 84 nails: 2 or 3 per joint by board width.
- Southern yellow pine (SYP) pallet lumberSouthern yellow pine (SYP, species class 22) is a dense, strong pallet softwood: about 4.45 lb per board foot green, 3.4 kiln dried, 1,300 psi in the engine.
- Bill of materialsA pallet bill of materials (BOM) lists every part with size and count. A GMA-style 48x40 BOM has 15 wood parts, 84 nails and about 13.5 board feet.
- BlockA pallet block is a spacer between the decks of a block pallet, usually 9 in a 3x3 grid. EPAL 1 blocks are 145 x 100 x 78 and 145 x 145 x 78 mm.
Sources
- PalletOne: choosing the best pallet nails
- PalletOne: anatomy of the block pallet
- Uniform Standard for Wood Pallets (NWPCA, now Woodpack Global), 2012 edition