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Glossary

Heat treatment

Also called: HT, ISPM 15 heat treatment

Reviewed

Definition

Heat treatment (HT) is the ISPM 15 phytosanitary treatment in which wood packaging is heated until its core reaches at least 56 °C (133 °F) for 30 continuous minutes. Treated pallets carry an ISPM 15 mark with the code HT and can be used for international shipments.

On this page
  1. How heat treatment works
  2. ISPM 15 treatment codes
  3. Rules that trip buyers up
  4. When it is required

How heat treatment works

Pallets or lumber go into a kiln or heat chamber until the core of the thickest piece holds 56 °C for 30 minutes. A certified facility, audited under a national program (in the US, the ALSC wood packaging program), then applies the ISPM 15 mark with the code HT.

ISPM 15 treatment codes

Code Treatment
HT heat treatment, 56 °C core for 30 min
DH dielectric heating, 60 °C for 1 min through the profile
MB methyl bromide fumigation (being phased out)
SF sulfuryl fluoride fumigation

Rules that trip buyers up

  • Wood must be debarked before treatment.
  • Repaired, remanufactured and combo pallets must be re-treated and re-marked, with old marks removed.
  • HT is not KD. Heat treatment targets pests, not moisture. Only KD-HT covers both.
  • Exempt materials: plywood, OSB, presswood, plastic and metal need no treatment, but a pallet mixing plywood with solid wood still does.

When it is required

Most countries require ISPM 15 for wood packaging on imports. Between the US and Canada it is not required at the border; between the US and Mexico it is. See ISPM 15 and heat-treated pallet.

Questions

What temperature is pallet heat treatment?
The wood core must reach at least 56 °C (133 °F) and hold it for 30 continuous minutes.
Do heat-treated pallets need re-treatment after repair?
Yes. Under ISPM 15, repaired and remanufactured pallets must be re-treated and re-marked, with the old marks obliterated.

Sources