Heat Treated Pallets: Everything You Need To Know

November 21, 2023
Written by Zach DoRflinger

Introduction to ISPM 15 and the Importance of Heat Treated Pallets

The international shipping landscape has a silent guardian that keeps the unseen threat of pests at bay. Known as International Standards For Phytosanitary Measures No. 15 (ISPM 15), this regulation is critical for businesses and ecosystems alike. It outlines measures to prevent the spread of insects and diseases through wood packaging materials (WPM) used in international trade. Heat treatment is a cornerstone of ISPM 15, requiring that wood used in pallets and other packaging materials be heat-treated to 56°C (133°F) for a minimum of 30 minutes. This process aims to eliminate the threat of pests such as wood borers and microorganisms that can compromise the integrity and safety of the goods during transportation

The Heat Treatment Process for Wood Packaging Materials

The meticulous process of heat treating pallets is critical in safeguarding our ecosystem from invasive species. Each pallet part must undergo a critical sterilization process before it's deemed safe for export.

The original procedures weren't always clear or straightforward. Initially, little was acknowledged about the duration or the specifics of the heat treatment process. Over time, industry testing shaped our current understanding and improved the efficiency of treatment protocols.

Steam Heat Treatment

Initial testing explored steam heat as a treatment medium. Tests revealed that using saturated steam environments could result in treatment times ranging from approximately 65 to 70 minutes for mixed hardwood pallets to 100 minutes for hardwood block pallets. Interestingly, steam treatment didn't significantly alter the moisture content or cause material degradation, though it did sometimes result in minor iron staining.

However, steam treatment can be energy-intensive and harsh on the heat treatment chambers. The corrosive nature of the saturated environment, exacerbated by the acetic acid content in woods like red oak, could quickly wear down the infrastructure.

Dry Heat Treatment

Exploring alternative methods, direct or indirect dry heat treatments were also examined. While it was slightly longer—taking up to 165 minutes for block pallets—this method led to some physical changes in the WPM, such as checks and separation of deck boards from the stringer due to cupping. These impacts demonstrate the need for precision in the treatment process.

Heat and Humidity Control

Next in the experimental lineup was the use of controlled humidity during heat treatment. A relative humidity of 62% paired with higher temperatures hinted at reduced treatment times without compromising the wood's integrity. The interplay between humidity and heat efficiency is a nuanced aspect of the sterilization process

The Global Impact of ISPM-15 and Heat Treatment

ISPM 15 has played a pivotal role globally by significantly reducing pest-related risks from WPM entering different countries. When WPM meets ISPM 15 standards, it receives a unique marking that certifies it as treated, creating a universal language of compliance and safety in international trade.

ISPM-15 Inspection and Enforcement within the United States

In the U.S., the responsibility of ensuring ISPM 15 compliance falls upon the shoulders of the Agriculture Inspectors at the USDA's Animal and Plant Health Inspection Service (APHIS). APHIS collaborates with U.S. Customs and Border Protection to conduct inspections at ports of entry, emphasizing the safety of agricultural imports.

There are currently 49 AQIM (Agriculture Quarantine Inspection Monitoring) ports in the U.S., involving maritime, airport, and land crossings with both Canada and Mexico. These ports witness around 6,000 WPM inspections annually as part of the AQIM program. The meticulous protocols in place ensure that containers and cargo are randomly selected and inspected, underscoring the importance of risk management in biosecurity

Consequences of Non-Compliance

The discovery of non-compliant wood packaging can have severe ramifications. When an actionable pest is detected, typically the entire consignment is regulated based on the pest's risk rather than the number of individual pests. This means a single violation can have overarching implications for the entire shipment.

Handling, Storage, and Risk Mitigation

After manufacturing and treatment, there are several stages where WPM is vulnerable to re-contamination. Cross-contamination can occur during packaging or if WPM comes into contact with pests while being stored at ports, emphasizing the need for continuous vigilance at every step of the supply chain.

Workers trained in the ISPM 15 standards are critical at distribution centers and warehouses. They are the last line of defense in intercepting and dealing with any signs of pest infestation, acting as custodians to protect not just the consignment, but also the environment into which it enters.


The adherence to ISPM 15 is more than a regulatory compliance issue—it's a commitment to an eco-friendly future in global trade. Heat treated pallets safeguard against the environmental and economic impacts of pest transfers, reflecting an integral part of sustainable business practices. Businesses and ecosystems equally stand to benefit from the diligent application of these standards. Through this vigilant approach, we protect our flora and fauna while fostering an ethical and responsible international trade industry. From mandates that pallets undergo rigorous heat treatment to inspections at every port of entry, these measures are a testament to what can be achieved through concerted global action. While heat-treated pallets are a simple component of cargo transport, their significance in the international trade environment cannot be overstated. They serve as silent protectors—guardians of ecosystems, economies, and ultimately, our global heritage.

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