ASTM D1586 vs ISO 22476-3: Which SPT Standard Applies to Your Project?

Two documents govern most SPT work outside Brazil: ASTM D1586 in North America and many international projects, and ISO 22476-3 in Europe, where it sits alongside Eurocode 7 (EN 1997). Brazilian projects follow ABNT NBR 6484. All describe the same test, but the details matter when results are compared.

Key differences

• ASTM D1586: 63.5 kg (140 lb) hammer, 760 mm (30 in) drop.

• ISO 22476-3: 63.5 kg hammer, 760 mm drop, with requirements to determine or report the hammer's energy ratio.

• NBR 6484 (Brazil): 65 kg hammer, 750 mm drop.

Always confirm the figures against the current edition of the standard cited in your contract.

Why energy correction matters

Energy delivered to the sampler depends on the hammer system: donut, safety or automatic trip hammer. Results are normalized with N60 = N × ER / 60, where ER is the measured energy ratio in percent. Automatic hammers typically deliver higher ratios than donut hammers, so the same ground can produce different raw counts with different rigs.

Choosing in practice

Follow the standard named in the specification. For export projects or multi-country work, choose equipment that supports an automatic hammer and consistent record keeping, so one rig can satisfy more than one standard.

Need drilling equipment built for compliance?

Diamond Drill builds rigs for geotechnical SPT work. Get in touch to discuss your standard and your ground conditions.