Many European standards refer to 'hazard' and 'service' classes when detailing the use of various panel products. These two classes are related but different and are easily confused.   Both define environmental conditions which will cause different equilibrium moisture contents in panels. A 'hazard' class describes the risk of biological attack in a given condition, while 'service' class is used to modify the mechanical properties of a 'dry' panel so structural designs have adequate safety margins.   The table shows there are three service classes, defined in the first part of Eurocode 5: Design of timber structures; and there are five hazard classes defined in EN 335 Durability of wood and wood based products. It's clear there is a link between the two class types, but that they are not exactly the same. The most striking difference is that the limits of the conditions of hazard class 2 would be classed as service class 3; here lies the risk of confusion.   For structural purposes, all panel types can be used in service classes 1 and 2 (for certain grades of a panel type). But for service class 3, only veneer based products can be used - with precautions to prevent bio-deterioration.   Densified panels - OSB, MDF and particleboard - should not be used in service class 3 conditions as they will swell, causing irreversible loss of mechanical performance. However, solid wood and many veneer based products will recover their mechanical properties when re-dried.   Under EN335, cement-bonded particleboard can be used in any of the hazard classes without preservative treatment. Plywood would have to be treated or made with naturally durable veneers.  

So-called 'illegal logs' are a big topic among legitimate US mill people concerned about price cuts affecting their profits. Others, however, might be generating more profits through using illegal material.   In his report, Dr Jim Bowyer challenges: "If you have in your product line wood that comes from anywhere in the tropics, the Russian Federation, or China, chances are good that a significant portion of that wood is of illegal origin. The fact you may be buying illegal wood matters. Illegality is directly linked to a number of problems, including corruption, financing of regional conflicts, forest loss and degradation, and the loss of billions in revenue to developing nations and to the domestic forest products industry".   Dr Bowyer, a retired University of Minnesota forestry professor, said The UK was one of the first governments to recognise the role of consumer countries in driving illegal logging, and the first to attempt to curb international trade in illegally logged timber. In 1997 the UK government issued voluntary guidelines for ministries regarding the purchase of timber and timber products from sustainable and legal sources. Implementation became mandatory in 2000.   In 2003 the European Commission announced an action plan on Forest Law Enforcement, Governance and Trade (FLEGT) under which EU governments would develop and implement measures to address illegal logging and related trade.   Later in the year came the US Presidential initiative against illegal logging to help developing countries combat such logging, selling and exporting of illegally harvested timber and fighting corruption in the forest sector. At the time, US Secretary of State Colin Powell estimated that governments were losing US$10bn to US$20bn annually to illegal logging.   Dr Bowyer said most illegally produced timber is used domestically and does not enter international trade. Illegal logging constitutes about 1% of global softwood and hardwood combined, but ranges from 12 to 17% of roundwood entering international trade. However, he said as much as 23% of hardwood lumber and plywood traded globally, and 2 to 4% of softwood lumber and plywood, may arise from illegal logging.   He said nations in which illegal timber makes up the greatest proportion of harvest are Indonesia, China and other Asian nations, West and Central Africa, Russia, Malaysia, Brazil and eastern Europe.   Last year Japan began requiring that all timber and timber products be harvested in a legal manner consistent with the forest laws of timber producing companies and harvested from forests under sustainable management.   New Zealand, Norway, Canada, Australia and the US are exploring options for removing illegal timber from their markets, while the US and Indonesia have an agreement focused on halting the flow of illegal wood from Indonesia. The Forest Products Association of Canada adopted a statement committing to purchasing and using wood only from legal sources and, by 2008, to trace all fibre back to the originating forest area.   Dr Bowyer concluded: "If you are involved in the international trade of timber, you have a responsibility to help solve the illegality problem. Proactive action to investigate potential problems in your supply chain is the responsible thing to do. It could help restore value to international timber trade and help improve the image of the forest sector in the public's eye".  

New plywood lay-up plants aren't popping up all over North America these days. Lowering housing starts, OSB competition and even raw material supplies are the leading factors limiting the plants.   Thompson River Veneer Products' plant, just east of Kamloops, British Columbia, has a completely new drying system, combined with equipment obtained from a mill in southeastern US. It opened last year in its new 75,000ft² building.   The mill buys and sells both green and dry veneer as well as plywood, with the proportions depending totally on the market. Plywood sales are in Douglas fir and Canadian softwood sheathing.   Suppliers truck Douglas fir, spruce, hemlock and balsam fir veneer to the mill in 1'7in, 1'8in and 1'10in thicknesses. Five acres of outside yard space provide storage; the climate is dry so outside storage is not a problem. A 9,000lb Toyota forklift services the storage.   "It's all market-driven," said Charlie Tate, production superintendent. "When dry veneer market prices are low enough, we'll certainly buy the dry and forgo drying the green. When we can dry the green cheaper, then we do the opposite. This mill is intended to play the marketplace and take its profit from there. We don't have to go with the punches."   Product is sold mainly in British Columbia with some in the Pacific Northwest of the US.   Regarding OSB competition, he said: "A plywood guy will always buy plywood. Plywood is probably the old-fashioned way of doing it - and a better way to do it. Every piece of wood you buy, when it gets out there, wants to bring moisture back in. With OSB, it's a little more so".   Thompson buys most of its veneers from one main supplier in BC which delivers it to the mill and generally has a back-haul to Vancouver, which works well. The mill also buys dry veneer from a variety of suppliers.   The mill has a Sweed feeder to a Coe jet dryer, running three shifts, with three heated sections, automatic feeding, and off-bearing to a Metriguard 2800 and a Ventek GS2000 automatic veneer grader.   The Ventek uses its own information, combined with that from the Metriguard and a Sequoia moisture meter, to grade each piece. These go to their assigned bins in an Elite 12-bin automatic stacker.   "We take the grades and apply them either for sale on the open market or use them for our own plywood manufacture," said Mr Tate.   Veneer bundles are strapped or marked for the mill's use and stored in the indoor warehouse.   Two Globe spreaders serve the press installation: a Globe pre-press, Globe loader, Burrard 30-opening press and Durand unloader. A panel feeder feeds single panels to the skinner and then to the cut-off Globe saw line cutting the 4x8ft panels as required, followed by manual grading and five sorting bins. Plywood production is 4x8ft sheathing in 3'8in to 3'4in thicknesses.   Next step will be to add tongue-and-groove plywood to the product line.   Among the values added to the veneer are LVL supply, concrete form panels, construction and industrial grade panels.   "It's been a tough market to grab workers," Mr Tate lamented. "Our workforce is new to this whole process. We've been training them from scratch. With the economy doing so well, you sometimes struggle to find the right people; we're lucky to have the people we do." The mill operates with 42 employees.   "I never thought I'd get the opportunity to be involved in a brand new plywood plant - it's the opportunity of a lifetime. It certainly has been challenging, right from the start-up," Mr Tate concluded.  

Natural gas has been a popular heat source for veneer dryers, but escalating gas prices have cancelled out some of that heat source's advantages and caused mills to look for alternative fuel sources.   One of the early companies to manufacture its own gas is Tolko Industries Ltd's Heffley Creek plywood operation near Kamloops, British Columbia.   Tolko partnered with Nexterra Energy Corp, Vancouver BC, in designing and building the new operation alongside one of Tolko's veneer dryers. Most of the manufactured gas heats that dryer, although some is used to condition peeler blocks.   The company estimates that the system, producing 38 million btu per hour, will save more than Can$1.5m in annual fuel costs, replacing 40% of the mill's natural gas consumption; this is 235,000 gigajoules per year. It also will reduce greenhouse gas emissions by some 12,000 tonnes per year.   The end product is clean-burning. In addition to replacing natural gas, it can substitute for propane gas and fuel oil in producing hot air and hot water, steam and even electricity.   The automatic plant runs around the clock, using 25,000 tonnes per year of bark and hog fuel with a moisture content of up to 60%.   Two gasifiers produce syngas; an oxidiser combusts the gas; a heat exchanger heats air for the veneer dryer; a boiler heats water for conditioning logs; and, to round out the benefits, VOCs (volatile organic compounds) from the dryer are consumed in the oxidiser.   In a principle rather similar to charcoal production, the wood is 'burned' while starved of oxygen, receiving about a quarter of that drawn to a normal fire. The product is mostly gas with a minor amount of wood actually burned and this produces the heat for the process. A granular ash remains, containing some nitrogen. A farmer whose fields adjoin the mill thinks it could possibly be used in those fields.   The system is much more versatile than burning the residues to produce heat. The syngas, a mixture of carbon monoxide, hydrogen and methane, can be used right along with natural gas.   In the process, the fuel comes from the debarker, dropping onto a 1,000ft-long conveyor belt lined with shut-off pull cords.   The fuel drops into a metering bin where a vertical auger system feeds the twin gasifiers where it is dried, undergoes pyrolysis, and is gasified.   Partially processed fuel is reduced to ash, which is automatically removed intermittently through openings.   The syngas leaves the gasifier at 500 to 700ºF (260-370ºC).   The heat comes down and proceeds either to an air-to-glycol heat exchanger, or to an air-to-air heat exchanger.   The emissions from the next-door dryer are fed into the oxidiser, located between the two gasifiers, for incineration. If the dryer is not operating, an alternative port provides outside air for the process.   The dryer is fed 22 million btus 600ºF (316ºC) hot air, while the glycol transferring heat to the vats is in the 145ºF (63ºC) range in summer and 170ºF (77ºC) in winter, taking 16 million btus. Block conditioning time is 12 hours.   The whole system operates automatically, controlled from an Allen Bradley Panel View Plus 1500. The various variables can be set on the screen and the status of every component is available on that screen.   With its three dryers in the mill, Tolko could possibly add a second system.   Hog fuel storage can hold 48 hours' worth of material and the system retains heat for 48 hours.  

In a major move to streamline its operations, Tolko Industries Ltd closed the plywood section of its Kelowna, British Columbia, mill last January and, at the same time, modernised and speeded the mill's veneer section. Less availability of high-quality peeler logs worked into the decision to overhaul this mill, built in 1957.   But the project was also tied in with the company's other mills. "The way the sheathing market has been going we are basically competing with each other," said Brett Patricny, plant quality control supervisor.   "We are going to peel veneer, recover high-value products, and then use the sheathing material to produce sheathing in the other mills," he said.   The spectre of beetle-killed trees hangs over most of this part of the world. Mr Patricny said the beetle kill is coming into this area "really, really quick. We can work with beetle kill standing in the bush for up to two years. We are not peeling much. It is used for core. Our stud mill saws it. About half of it is lodgepole pine".   The veneer line peels 80% spruce-pine-fir and 20% Douglas fir, operating with a crew of 40, with one 10-hour shift on the lathe and two 101'2 hour drying shifts.   The Premier lathe with Coe drive has drawn most of the recent work, with an Altec x-y scanner 3-D from LMI Technologies accommodating up to 64 lasers, and new lathe controls. Tolko and Premier collaborated on a proprietary, custom-made carriage design which has emphasis on electric motors rather than hydraulics for moving the carriage. There are now two AC motors on the lathe.   For super-fine control, up to 200,000 readings are taken on each block with the computerised scanner optimiser, providing very even thickness - normally ±0.008in. This system provides thicknesses in the ±0.002in range.   The roller bar was reduced from 33'4in to 21'2in and that provides a smaller peel, according to Mr Patricny.   The average block diameter is 101'2in, with 3 to 4,000 blocks peeled per shift. Maximum diameter is 35in with a 71'2in minimum. The mill peels down to a 3in core diameter. The veneer off-bears to three trays operating at speeds up to 1,000fpm. Past the clipper, it proceeds through a Forintek-Westmill LightSORT moisture detector based on a fairly simple principle that the higher the moisture content, the more light passes through the sheet. But augmenting that principle requires quite sophisticated equipment.   It uses CCD camera and LED light transmission, pulsing specific wavelength light through the veneer where the camera takes an image. Algorithms determine the exact peak and average moisture content for each sheet. It works well with high moisture content veneer, which is a problem for radio frequency (RF) sensor heads.   Forintek ran tests on the Tolko system and found a 10% production gain, based on 7.6% on dryer output, 2.5% gain in target dry veneer, and a 2.7% reduction in re-dry.   Brian Martin, Westmill Machine Automation general manager, said the system does not require veneer contact and, unlike RF measuring, veneer variables are not a problem. The system also checks the entire sheet, rather than just the veneer passing under the heads as in other systems. This not only results in a highly accurate sort and consequent increase in dryer productivity, but also increases final veneer quality, he said.   The veneer off-bears to six bins - two for heartwood, two for medium, two for heavy.   A Raute direct-fired jet gas dryer has four decks, while two six-deck steam dryers have been in place since the plant was built in 1957. A Coe scanner is on dryer number one and a Metriguard is installed.   Tolko built its own stackers, with 18 bins on one and 12 on the other. Samuels automated strapping will soon be added.   Most of the veneer is used within Tolko's other plants, with the aim of developing a group of specific customers and serving them well.   Tolko separates species in the bush and is not buying so many logs. The plant operates one 10-hour lathe shift and two 101'2 hour drying shifts with production of 1.7m ft² (3'8in basis) weekly. The mill has a crew of 40.   Log storage is all in water, with the log dump on the far side of the 13'4-mile-wide lake. Logs are graded on the far side and rafted across the lake; though winters are quite cold, it rarely freezes. In winter, frozen logs from the bush are common and they get a thawing head start in the lake.   Logs come to a common cut-up for veneer and the adjoining stud mill. They go through a ring debarker, with hogged bark sent to the power plant, which provides six to seven megawatts of power to make the mill almost self-sufficient.   Three hot water vats heat veneer blocks to 100ºF (37.8ºC) core temperature.   Both truck and rail shipping move product out. A rail siding holds two cars behind the mill, with room for another four.  

There are times when the 'global market' that everybody talks about really makes itself felt and not always in a positive way.
The US is certainly making itself felt globally as I write this column, with the poor state of its housing market having major repercussions in two main areas at least.
Firstly, of course, there is the severe downturn in the market for structural panels in the US. Although this mainly impacts on the North American producers, there was a time, not so long ago, when European OSB manufacturers were exporting to the booming US market, which couldn't make enough to meet the demand. In the UK, where I am based, the impact of the US housing slump has, in the middle of September, wreaked havoc in the banking and political systems. The crisis in the US sub-prime mortgage market has affected the climate for borrowing and lending around the world, but the immediate effect in the UK has been to expose the weakness of the nation's eighth largest bank and fifth largest home loans provider, The Northern Rock bank. The government has, in an unprecedented move, stepped in to guarantee savers' funds deposited with the bank, without limit, as its share value plummets. At least one other UK bank is also being viewed warily by the public and by financial institutions.
In an economy such as the UK's, built largely on very heavy personal and national debt, these are worrying signs. I suspect that other countries might well have similar problems in their banking systems if the financial turbulence continues. As money supply becomes tighter around the world in the wake of the problems in the US, we must hope that the very encouraging signs of growth in the panel manufacturing industry, so apparent at the Ligna show in May, and since, are not adversely affected. Some very significant news within our own industry is the takeover by Siempelkamp of Germany of the continuous press and energy plant division of Metso Panelboard of Finland (see p6), located in Hanover, Germany. As many readers will remember, the Metso Contipress was originally the Küsters continuous press, with its unique chain system behind the endless stainless steel belts. It is also one of only three continuous presses on the world market (so far - we still await definite news from China on a new competitor press) and now Siempelkamp owns two of them. The takeover came into effect at the end of September so it is still early days. Siempelkamp has announced that it will continue to supply spare parts for the Contipress, but has only mentioned continuing full manufacture of the energy plants at Hanover......  

The Roy O Martin mill in the tiny timber town of Chopin, Louisiana, just got bigger with an entirely new Coe high speed small-log lathe line, dryer, lay-up line and press. This was a US$56m project. By the second quarter of 2008, when up to full production with the new addition, the mill will be turning out nine million ft², 3'8in basis, of panels weekly with a current staff of 528.   Martin is not lacking for raw material. It owns 580,000 acres of Forest Stewardship Council-certified timberlands, with its mills placed in the most efficient locations for minimum hauls. The firm is vertically integrated into plywood, OSB, hardwood lumber and poles for the transmission industry.   Most raw material comes from a 30- to 35-mile radius and while much of the logging is contracted, Martin also has a subsidiary logging company.   Joe Mackay, the company's plywood vice-president, said, "Our log yard has l8in thick concrete. We can store at least 30 days' of wood on the slab, but we don't tend to leave that much out there."   Rain slows hauls in the January to March period, but volumes are fairly steady through the rest of the year.   A Taylor log stacker, Volvo 340, or Caterpillar 96 unload and handle logs, with about 80 truck loads arriving daily, seven days a week. For the new line, a LeTourneau rotary crane loads the deck to a PSI unscrambler and singulator to a Nicholson 27in debarker. Oversize goes to the existing log processing.   Two scanners can handle tree lengths up to 62 feet. This provides a dimension scan for plywood blocks as well as identifying poles for length and class. Poles are treated at Martin's Pineville mill.   The small tops are chipped in a large Valon Kone 600hp chipper, while the blocks, sorted for diameter, move to one of six vats for 160ºF (71oC) water conditioning for 12 to 16 hours, producing core temperatures of 105ºF to 110ºF (40-43oC).   A Linden log ladder leads up to the Coe turnkey-project lathe line, equipped with a camera-based x-y charger and Alpha Omega software for optimising block positioning. The system peels an average of 12 blocks a minute, with a peak of l6.   Three-stage retracting chucks are included, with the smallest being 21'2in. Veneer off-bears by a clipping trash gate onto three 100ft trays and to a Durand-Raute clipper supported by Ventek software. A Coe diverter directs veneer to a pair of two-bin stackers.   Included in the expansion project was an 18-door Coe jet dryer with Accumatic vacuum feed and 14-bin Coe stackers.   On the original 1995 line a Raute 28in lathe, with Elite x-y scanner upgrade, handles blocks 12in and larger. "We segregate around a 10in block to the Coe lathe," said Mr Mackay.   Veneer from the Raute goes to four 120ft clippers and to a Durand-Raute clipper, two three-bin stackers and a short green chain for strip and fish-tail.   Three existing Raute jet dryers are fired by two Wellons furnaces with 74 million btu/hour capacity each, assisted by a new Teaford furnace producing 80 million btu/hour. Heating is totally by thermal oil.   Two 29-section Raute dryers are installed, along with a 20-section Raute for re-dry and strip. The output of each of the large Raute dryers goes through either a Ventek GS2000 defect analyser or a Mecano veneer defect analyser into a 14-bin stacker. Ventek, Sequoia and Sentry moisture meters are installed.   "We have a high-moisture drying programme so we sort into four different moisture sorts in five different grades," Mr Mackay explained.   Such moisture content emphasis is a product of the mill's timber supply. He said the southern pine forest is l00% second growth: "The second-growth trees don't produce a significant amount of heartwood."   He continued: "We choose to lay up all our veneers into plywood. We do not sort for the LVL industry. Our veneer is 18-22% high grade; we can make more money selling plywood than veneer. While LVL can offer some significant advantages in a poor market, in a medium or strong market we're better off. With LVL we would be giving up our best veneer."   An 18-door Coe jet dryer with Accumatic vacuum feed and a 14-bin Coe stacker were part of the new installation. Martin also rebuilt one of the Raute jet dryers.   Five Raimann patchers work 12 hours a day, seven days a week, producing about 50,000 faces weekly. Patched veneer off-bears to a circular sorter.   The glue technician mixes for both the spray line and the foam line without touching a bag; the whole mixing process is controlled by weight.   A new Spar-Tek seven-ply foam lay-up line, with four feed stations and three core stations, takes CD veneer and lays it up into industrial and sheathing grade to feed a Spar-Tek pre-press and a fast-closing Spar-Tek 50-opening 4x8ft hot press. For five-ply, pressing time is 5.5 to 6 minutes at 315ºF (157oC). Pressure of 200psi is applied for 120 to 180 seconds, after which the press goes to position control.   The press frame is built with two vertical end frames which are keyed and bolted to matching machined faces on the cylinder base and press crown. This produces a solid structure which maintains its integrity with no movement during a press cycle.   Another feature to simplify maintenance is an adjustable platen guide system with replaceable brass wear strips attached to the end frames, which can be adjusted for wear or replaced without disassembly.   The mill already had two Raute 50-opening presses, bringing the total to 150 openings.   About half the panels are trimmed by the Globe saw line, strapped, and go directly to distribution channels while the balance goes to the finishing department - to two Globe routing and filling lines and then to either a six-head Kimwood sander and a five-in line Globe, or to a Kimwood two-head sander and a speciality saw.   A Samuels automatic strapper serves all the lines.   The output is shipped 60% by rail and 40% by truck with Midwest, Southeast and California the major markets.   The production is a full range of speciality sanded, 1'4in to 11'8in, textured siding, AA, AB, BB, BC and industrial siding.   One speciality is beaded interior panels, pre-sanded and ready to paint. Premium 303 exterior siding is produced in rough-sawn or scratch-sanded face.