If your business ships goods internationally using wood pallets, understanding the International Standards for Phytosanitary Measures No. 15 — commonly known as ISPM-15 — is not optional. It is a widely adopted requirement checked by plant protection and customs authorities in many countries. Non-compliance can result in rejected shipments, costly delays, quarantine fees, and even destruction of your goods at the port of entry.
ISPM-15 was developed by the International Plant Protection Convention (IPPC), a treaty organization. The standard exists for one critical reason: to prevent the international spread of invasive insects and plant diseases that hide inside raw wood packaging materials. Bark beetles, wood-boring insects, nematodes, and other destructive organisms can survive inside untreated wood for months, hitching rides across oceans with cargo.
What Is Heat Treatment for Pallets?
Heat treatment is the most widely used method for achieving ISPM-15 compliance. The process requires that the core temperature of the wood — not just the surface — reaches a minimum of 56 degrees Celsius (132.8 degrees Fahrenheit) and is maintained at that temperature for at least 30 consecutive minutes. This thermal threshold is intended to kill the regulated pests that can live in wood, at every life stage.
The treatment is performed in heat treatment chambers, essentially large industrial kilns equipped with calibrated temperature probes inserted into test samples of wood. The probes measure the internal temperature at the core of the thickest pieces to confirm the heat penetrates fully. Treatment providers are authorized by their national plant protection organization and are expected to keep detailed records of each treatment cycle, such as time-temperature logs and batch details.
It is important to understand that kiln drying alone does not satisfy ISPM-15 unless the process specifically achieves and documents the 56°C/30-minute core temperature threshold. Many kiln-dried lumber products reach high surface temperatures but may not sustain the required core temperature for the full duration. Only authorized treatment providers can apply the ISPM-15 mark.
The ISPM-15 Mark: Reading the Stamp
Once a pallet has been properly heat treated, it receives a standardized mark — often called the "wheat stamp" because of the IPPC logo that resembles a stalk of grain. This mark must be permanently applied to at least two opposite sides of the pallet using a branding iron, stencil, or ink stamp. Stickers and adhesive labels are not acceptable because they can fall off in transit.
Components of the ISPM-15 Mark
Customs officials at ports worldwide are trained to look for this mark. A pallet without it — or with a mark that is illegible, incomplete, or does not include the required HT treatment code — will be flagged. Depending on the destination country, consequences range from mandatory fumigation at the importer's expense to refusal of entry and return of the entire shipment.
Heat Treatment vs. Methyl Bromide
ISPM-15 originally allowed two treatment methods: heat treatment (HT) and methyl bromide fumigation (MB). However, methyl bromide is an ozone-depleting substance regulated under the Montreal Protocol, and it is not generally used for new pallet treatment today. Some countries restrict or bar MB-treated wood packaging, so heat treatment is the practical choice for exporters.
Heat treatment leaves no chemical residues on the wood and is the method most commonly used and accepted. Always confirm your destination's current rules before shipping, since acceptance of any treatment code is set by the importing country.
From a practical standpoint, heat treatment is also well suited to high-volume operations. A heat treatment chamber can process many pallets per cycle, and cycle times depend on wood thickness and moisture content. The process is repeatable and documented, which is what customs inspections look for.
Steps to Ensure ISPM-15 Compliance
Whether you are an exporter, freight forwarder, or warehouse manager, here are the essential steps to ensure your wood packaging meets ISPM-15 requirements:
Phoenix Pallet Recycling connects requests from Phoenix and the Valley with partner suppliers. If you need heat-treated pallets for export, say so in your request, including the size and quantity, and a partner supplier can tell you what is available. Availability depends on partner suppliers.