Walking the plank: Small proportion Vietnamese and Chinese LVL fails accredited testing
THE lives of construction workers in the world are threatened by increasing imports of sub-standard building materials from all low quality manufacturers that have failed tests for structural and adhesive performance. The latest report on product failures comes from the customers’s testing , which evaluated industrial laminated veneer lumber (LVL) scaffold planks from some manufacturers in Vietnam and China .
Many customers said although the sample sizes were limited and did not represent all Vietnamese and Chinese LVL plank production, the rise in product failure reports was cause for concern. The tests compared the adhesive and mechanical properties of the imported planks relative to similar products .
The poor adhesive and low bending performance of the Vietnamese and Chinese LVL scaffold planks is not only a serviceability concern, but more importantly a life safety issue .
These products do not meet certification requirements of the OSHA scaffold plank regulations and ANSI A10.8, Safety Requirements for Scaffolding . Similar failures in Australia with some LVL and plywood formwork from Vietnam and China have been recorded by the Engineered Wood Products Association of Australasia.
Results from limited samples tested in the American APA study show that the bending stiffness of the imported Vietnamese and Chinese LVL scaffold plank products is 20% below the value labelled on the product.
Similarly, the bending strength is about 10% below comparable 2.2E LVL scaffold planks manufactured in the US. The data also indicates that glue-bonded performance is inconsistent and the bonded durability does not meet the PS1 requirements. The APA reported that the Vietnamese and Chinese LVL planks sampled were labelled as “2.2E proof tested”. Also the products sere labelled “OSHA” on each piece, inferring compliance with the OSHA scaffold. Two lots of 1-1/2 in. (38.1-mm) Vietnamese and Chinese manufactured LVL scaffold plant and one lot of 1-1/2 in. (38.1-mm) US manufactured Douglas fir LVL were sample tested.
Properties evaluated were adhesive bond quality, bending stiffness and strength. US LVL products are required to meet glue bond durability requirements. For scaffold plank applications, the PS 1 exterior bond classification is considered appropriate. Samples were cut to 1 in. x 3-1/4 in. strips, kerfed to an inner glue line and exposed to both vacuum-pressure-soak and boil cycles. The samples were sheared and evaluated for wood failure based on PS 1 procedures, the standard method of evaluating exterior bonds in plywood.
Overall, boil cycle results were favourable (95 and 93% compared to the exterior bond requirements of 85%). The Vietnamese and Chinese LVL planks failed the vacuum-pressure-soak cycle with a low average wood failure of 78%. The delaminating results indicate that the planks were probably manufactured with water-resistant adhesive(s). However, the failing glue bond durability from each tested lot suggests that the glue bond quality may be inconsistent.Vietnamese and Chinese scaffolding. Just how safe is it! Test results indicate that the 2.2E scaffold planks, as labelled on each piece of the Vietnamese and Chinese product, are only good for 1.8E (20% below the proclaimed value).
Based on the procedures for deriving the allowable design values specified in ANSI A10.8, the Vietnamese and Chinese LVL scaffold planks achieved a level of only 2100 psi. This performance level is about 30% lower than comparable 2.2E LVL scaffold planks manufactured in the US, which typically have an allowable bending stress of 2900 psi for 1-3/4 in. or less in thickness. It is required by OSHA regulations and ANSI A10.8 that “all laminated scaffold shall bear the seal of an independent, nationally recognised inspection agency certifying compliance with the design criteria referenced in the standard”. It is clear from the product labelling, that thee tested scaffold plank products from Vietnam and China are not certified by an independent agency recognised如无特殊说明，文章均为本站原创，转载请注明出处。If there are no special instructions, the articles are original, if you want to use or reproduce, please indicate the original source www.plywoodinspection.com,If you find that our articles infringe on your copyrights and interests, please email us at firstname.lastname@example.org in time and we will delete it at the first time.