Heat treatment can be achieved through various energy sources or processes that meet the specified parameters. These may include conventional steam heating, kiln-drying, chemical pressure impregnation with heat, and dielectric heating methods like microwave and radio frequency.
National Plant Protection Organizations (NPPOs) must ensure that treatment providers monitor the temperature at the coldest point in the wood, which is the slowest to reach the target temperature, to maintain it for the required duration across the entire batch. The coldest point in the wood varies based on the energy source or process used, the wood's moisture content, and its initial temperature distribution.
For dielectric heating, the surface is typically the coldest part during treatment, although the core may be coldest in certain situations, such as when treating large, previously frozen dimensions of wood until it thaws.
For heat treatment using conventional steam or dry kiln heat chambers (marked with the treatment code HT), the essential goal is to reach a minimum temperature of 56°C for at least 30 continuous minutes throughout the wood's entire profile, including the core. This can be monitored by placing temperature sensors inside the wood's core. Alternatively, treatment schedules for kiln-drying or other heat treatment chambers can be established based on test treatments that measure and correlate the core temperature of the wood at different points within the chamber with the chamber air temperature, considering the wood's moisture content and other factors.
A detailed process flow for the ISPM-15 treatment of wood using forced hot air treatment:
1. **Wood Receipt**
- Receive and inspect the wood for quality and quantity.
- Verify compliance with ISPM-15 requirements.
2. **Sorting and Preparation**
- Sort wood based on size and quality.
- Remove any defects or contaminants.
- Ensure wood is debarked to remove outer layers where pests may reside.
3. **Stacking**
- Stack wood in a way that allows for proper airflow.
- Ensure stacks are stable and secure.
4. **Forced Hot Air Treatment**
- Load wood into the treatment chamber.
- Heat wood to a minimum core temperature of 56°C (133°F) for at least 30 minutes.
- Monitor temperature and humidity levels continuously.
- Ensure uniform heat distribution throughout the wood.
5. **Cooling**
- Allow wood to cool to ambient temperature.
- Ensure cooling is done in a controlled environment to prevent recontamination.
6. **Marking**
- Apply the ISPM-15 compliant mark to the wood packaging material.
- Ensure the mark includes the IPPC logo, treatment method code (HT for heat treatment), and the country of origin.
7. **Documentation**
- Prepare and maintain treatment records.
- Issue a Phytosanitary Certificate.
- Ensure all documentation is complete and accurate for customs clearance.
8. **Storage and Shipment**
- Store treated wood in a clean, dry area.
- Prepare for shipment to the final destination.
- Ensure proper labeling and packaging for transport.
9. **Inspection and Compliance**
- Conduct final inspection to ensure compliance with ISPM-15 standards.
- Verify all documentation and treatment records are in order.
10. **Shipping**
- Arrange for transportation of the treated wood.
- Ensure compliance with international shipping regulations.
11. **Post-Shipment Follow-Up**
- Monitor the shipment to ensure it reaches its destination without issues.
- Address any concerns or complaints from the receiving party.
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Heat Treatment - ISPM-15