 |
 |
 |
             
|
|
|
|
|
Purchasing Decisions Laminated Veneer Lumber — 
Smart purchasing decisions are crucial, especially when it relates to worker productivity and job site safety. Our competitive business environment, however, often leads to marketing approaches that can ultimately confuse any prospective buyer. It is unfortunate that the wood products industry has not made your purchasing activity any easier. In fact, the industry has been somewhat negligent in properly educating you, the contractor, about wood plank, and in particular Laminated Veneer Lumber (LVL)-type scaffold boards. To be an informed consumer, it is important for you to understand how this engineered wood plank evolved, how it is manufactured, the product attributes and, of course, the crucial questions to get answered when inquiring to purchase. From the beginning In 1974, Trus Joist Corp., Boise, Idaho, began producing a new type of engineered wood known as Laminated Veneer Lumber (LVL), which is, essentially, a modified version of traditional plywood. Shortly thereafter, McCausey Lumber Co., Roseville, Mich., partnered with FinnForest Corp., Metsa, Finland, to develop a version of Laminated Veneer Lumber. Today, there are more than twenty LVL producers worldwide.
For most manufacturers, production is geared to produce LVL wood beams for residential and commercial construction. Yet, a few have focused more toward producing a select grade of LVL that is made with a special veneer grade composition for industrial applications, such as scaffold plank.
Laminated Veneer Lumber Some manufacturers purchase kiln-dried veneers on the open market while others peel their own logs, kiln dry the veneers, then select and organize them according to grade quality. The dried veneers are then sequentially fed, relative to grade designation, into the highly automated production line where they are coated with adhesive, slightly lapped end-to-end, and stacked in layers to the desired thickness. The production line precisely controls the exact placement of each veneer, relative to grade quality, and ensures that all lapped joints are dispersed uniformly throughout the entire panel lay-up.
The long continuous ribbon of stacked veneer is then fed through a hydraulic press where, under heat and pressure, they are bonded into a thick, uniform panel known as a billet. Essentially, the billet appears to be a very large plywood panel, but, again, the veneer grain direction is orientated parallel to one another.
Depending upon the production line capabilities, a billet can range from 3/4 to 3-1/2 inches thick, by 24 to 96 inches wide and as long as 48 feet in length. Ultimately, the billet gets precision ripped to width and cut to length relative to the desired product size needed for the specific application.
Obviously, the following description is simplified, but essentially all LVL plants are formatted the same with the exception of some proprietary equipment. This unique manufacturing process provides for a uniform, homogeneous lumber type product with predictable strength. Yet, every mill tries to differentiate by using certain wood species and their own special combination of veneer grades within the lay-up process. Billet to plank All legitimate LVL scaffold plank manufacturers should have an in-house quality control program outlining procedures for proof-testing scaffold plank. They should be testing every plank to ensure strength properties are adequate to carry the load capacities as specified by the American National Standards Institute (ANSI) and observed by OSHA.
In addition, ANSI standard A10.8-2001 specifies "all laminated plank shall bear the seal of an independent, nationally recognized inspection agency certifying compliance with the design criteria."
In other words, all producers must have an outside third-party agency that is accredited by the National Evaluation Service (NES), to regularly monitor the manufacturers' quality control program and testing procedures. Essentially, qualified LVL scaffold plank producers go the extra mile to mechanically test their product under watchful eyes. To date, solid lumber plank mills merely visually grade their planks and attempt to pull out boards that do not appear to be up to standards.
Upon acceptance, each qualified LVL scaffold plank is identified with an ink stamp bearing the following information:
Finally, manufacturers will typically machine a slight radius (or bevel) on plank edges to minimize splintering and seal coat the plank ends to minimize moisture absorption and end checking.
Technically advanced As noted earlier, LVL manufacturers try to differentiate their product from their competitors by using different wood specie (for example, spruce, southern pine or Douglas fir). Since each wood species has a different density, the species of choice, combined with the veneer grade lay up pattern, directly relates to the strength properties of the finished product.
In addition, the chosen wood species also correlates to the physical handling weight of the LVL plank itself. Therefore, it is crucial that you study the allowable span tables of each brand of LVL plank being considered to ensure you chose the right product for your application and scaffolding equipment.
Determining strength Fiber Bending (Fb) value corresponds to a plank's resistance against an applied load and the relative tension and compression of wood fiber within the plank. Modulus of Elasticity (M.O.E.) is the measurement of a planks' stiffness or the association between the amount a plank deflects and the load causing the downward deflection. Note: In the United States, OSHA observes a deflection limit of L/60, where as "L" represents the length of plank span (inches). In Canada, the regulatory agency, known as CSA, endorses more stringent criteria of L/80.
Given the above factors, you are probably still wondering how to make the right choice. The fact is there are some sales organizations that purchase standard grade LVL and "supposedly" conduct their own proof testing. You guessed it! They offer plank that may not be properly inspected or qualified pursuant to the traditional and proven methods of testing — and of course at a reduced price.
So, how do you qualify your decision and avoid possibly purchasing a plank that has not been properly produced and tested, and may not meet the appropriate ANSI and OSHA standards? More importantly, how do you protect the interest and safety of your workers?
One way is to make a checklist to note the supplier's credentials, product features and benefits, as well as any questionable circumstances behind each LVL plank product being considered.
Yes, there is truly more to making the best purchase decision than merely cost. You simply cannot put a price on the safety of your workers nor the liability behind your decision.
The standard solid wood plank for scaffolding is the Dense Industrial 65 (DI65) sold by supply companies, distributors and directly from the manufacturers. One of the latter is Kennison Forest Products, Sulphur, La., Dick Kennison, president and CEO of the company, claims, "In over 30 years of experience with DI65, we have had no reports of plank failure when the plank is cared for properly while not in use. The life of DI65 scaffold plank is as long or longer than its laminated counterpart and DI65 is lighter in weight. In addition, DI65 costs as much as 20 percent less than laminated plank."
Good arguments in keeping solid wood on your scaffold. But Kennison isn't done extolling the virtues of solid wood. "Dense Industrial 65, while suitable for all uses, actually excels in wet or very humid conditions because solid sawn wood doesn't absorb moisture as readily as laminated plank."
And both, of course, are OSHA and ANSI certified for use on scaffolding, meeting or exceeding published standards. As Kennison says, "Both are graded and/or tested for all uses. However, we feel the integrity of solid sawn DI65 is easier to maintain."
Yes, it's basically a matter of preference but when you look at all the factors, DI65 should win out according to those who cut lumber for a living.
|
|
  |
www.masonrymagazine.com
MASONRY
©2002 by the Mason Contractors Association of America