Heat treatment


Given that wood packaging material used in international trade can be a way of introduction and spread of quarantine pests, The International Convention For The Protection Of Plants Of FAO requires all countries to use debarked wood prior to subject this to a specific treatment, approved and marked with the IPPC/FAO.

This activity is required for two reasons:

1. Protecting forests from pests originate from other continents;
2. Minimize obstacles to international trade.

For the above, an entire industrial/crafts sector, consisting of several categories of production (sawmills, new and used pallets, crates and cages, industrial packaging, vegetables packaging), it had to be adapted to the ISPM-15 phytosanitary standard (Regulation of wood packaging material in international trade).

Among the activities provided by the standard ISPM-15 for the production of wood packaging material there is the TREATMENT, required step to affix the IPPC/FAO in accordance with the requirements. According to the rules and guidelines laid down by the European Union, the only treatment methodology recognized since 2010 is the thermal treatment (code "HT"). This activity is carried out in a drying kiln and foresees to raise temperature at the core of the wood to at least 56°C for a minimum time of 30 minutes (so-called direct method).

How is the process of heat treatment? These are the main steps:

HEATING: During this phase the timber is heated in a gradual and quick manner.

HT TREATMENT (Phytosanitary treatment according to standard FAO ISPM-15): For some applications it is required that the material is treated at high temperature in order to reduce the possible presence of undesired micro-organisms. This phase allows to certify a wood temperature always above a certain value for the time necessary (direct method = 56°C in the heart of the wood for 30 minutes).

COOLING: Before being picked from the cell the material is cooled; the reduction in temperature will be about a third of that reached during the drying phase. In winter it will be further reduced so as to avoid excessive thermal excursion than the outside temperature.


The types of packages that can be treated: sawn timber of any type of wood, new and used pallets, crates, cages, cassettes, Euro pallets and EPAL or pallets outside the standard.

The features that distinguish the installations TERMOLEGNO:

1. thermal cells properly insulated and sealed both thermally and acoustically;
2. ventilation system that ensures a flow of hot air uniformly to all the heat treatment system (around and through the pallets) corresponding to the needs of the wood to be treated, sufficiently sized to ensure the maintenance of the temperature at the core of the wood at the required level and for the established duration;
3. heating system proportionally dimensioned and designed to accelerate the treatment times;
4. EPDM rubber deflector (resistant to temperatures between -40°C and +120°C) positioned between the sub ceiling and the last row of pallets in height;
5. instrumentation for measurement and registration properly calibrated to ensure proper system for measuring the temperature in the heart of the wood;
6. verification system of the process probes before starting the installation for heat treatment;
7. appropriate electronic system certifying IPPC/FAO with certificate of treatment.

The types of systems that can be realized are varied: Termolegno is able to design and produce systems of different types based on the needs of the customer. Several sources or energy processes are adequate to achieve the required treatment parameters. The most commonly used are:

1. direct gas heating (natural gas or LPG) through an aspirated burner;
2. heating batteries fed with fluid such as hot water, superheated water, steam or diathermic oil produced by different types of heat generators (waste wood boilers, gas boilers, oil boiler);
3. Direct oil heating.

The types of possible load are the following:

1. front loading with forklift;
2. tunnel loading with trolleys on rails.

The opening types of drying kilns:

1. sliding monobloc door;
2. monobloc door to slide up the side wall - Swivel to 90 degrees;
3. door to door.

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