1、 Reference number ISO 18776:2008(E) ISO 2008INTERNATIONAL STANDARD ISO 18776 First edition 2008-02-01 Laminated veneer lumber (LVL) Specifications Lamibois (LVL) Spcifications ISO 18776:2008(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, t
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6、 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2008 All rights reservedISO 18776:2008(E) ISO 2008 All rights reserved iii Contents Page Foreword iv 1 Scope . 1 2 Conformance. 1 2.1 Quality system requirements 1 2.2 Manufacturing
7、specifications 1 3 Normative references . 2 4 Terms and definitions. 2 5 Materials 3 5.1 Veneer 3 5.1.1 General. 3 5.1.2 Species 3 5.1.3 Thickness 3 5.1.4 Quality 3 5.1.5 Jointing 4 5.2 Adhesives 4 6 Bonding quality. 4 7 Lay-up (arrangement of veneers) 4 8 Dimensions, shape and tolerances. 4 8.1 Dim
8、ensions 4 8.2 Shape . 5 8.3 Tolerances . 5 8.3.1 Dimensions 5 8.3.2 Shape . 6 9 Determination of properties. 6 9.1 Physical properties. 6 9.2 Mechanical properties 6 9.2.1 General. 6 9.2.2 Structural applications. 6 9.3 Supplementary properties . 6 10 Preservative and chemical treatments . 7 10.1 Na
9、tural or confered biological durability 7 10.2 Effect of chemical treatments 7 11 Formaldehyde release 7 12 Marking (identification) 7 Annex A (normative) Veneer quality 9 Annex B (normative) Panel construction (Veneer arangement) . 10 Annex C (informative) Properties to be determined depending on e
10、nd use 11 Annex D (informative) Supplementary properties 12 Bibliography . 13 ISO 18776:2008(E) iv ISO 2008 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing Internati
11、onal Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with IS
12、O, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical co
13、mmittees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the
14、 possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 18776 was prepared by Technical Committee ISO/TC 89, Wood-based panels, Subcommittee SC 3, Plywood. INTERNATIONAL STANDARD
15、 ISO 18776:2008(E) ISO 2008 All rights reserved 1 Laminated veneer lumber (LVL) Specifications 1 Scope This International Standard specifies the requirements for Laminated Veneer Lumber (LVL) for general purposes and structural applications, in dry, tropical-dry/humid or high humidity/exterior condi
16、tions. Laminated Veneer Lumber (LVL) is a general description for an assembly of veneers laminated with an adhesive in which the grain direction of the outer veneers and most other veneers is in the longitudinal direction. This International Standard specifies requirements for the quality of veneers
17、, bond durability, tolerances on dimensions, and structural characterization. Characteristic values, to be used for design purposes, are based on testing and evaluation of laminated veneer lumber. 2 Conformance 2.1 Quality system requirements Products conforming to this International Standard shall
18、be manufactured to a formalised manufacturing specification covering all relevant process variables under a quality system which includes in-plant process quality control and internal auditing procedures, and external auditing of plant process control and end-product quality. The system shall be con
19、sistent with the requirements of ISO/IEC Guide 65. 2.2 Manufacturing specifications The manufacturing specifications shall set the limits on all variables that affect or correlate with final product properties, including a) materials (see Clause 5), b) bonding quality (see Clause 6), c) lay-up (cons
20、truction) (see Clause 7), d) manufacturing process, and e) secondary processes and treatment (see, for example, Clause 10). NOTE The above list is not necessarily exhaustive. ISO 18776:2008(E) 2 ISO 2008 All rights reserved3 Normative references The following referenced documents are indispensable f
21、or the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO/IEC Guide 65, General requirements for bodies operating product certification systems ISO 2074, Ply
22、wood Vocabulary ISO 9427, Wood-based panels Determination of density ISO 12460-1, Wood-based panels Determination of formaldehyde release Part 1: Formaldehyde emission by the 1-cubic-metre chamber method ISO 12460-2, Wood-based panels Determination of formaldehyde release Part 2: Small-scale chamber
23、 method ISO 12460-3, Wood-based panels Determination of formaldehyde release Part 3: Gas analysis method ISO 12460-4, Wood-based panels Determination of formaldehyde release Part 4: Dessicator method ISO 12466-1, Plywood Bonding quality Part 1: Test methods ISO 12466-2, Plywood Bonding quality Part
24、2: Requirements ISO 16978, Wood-based panels Determination of modulus of elasticity in bending and of bending strength ISO 16979, Wood-based panels Determination of moisture content ISO 21887, Durability of wood and wood-based products Use classes ISO 27567, Laminated veneer lumber Measurement of di
25、mensions and shape Method of test 4 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 2074 and the following apply. 4.1 laminated veneer lumber LVL product made of an assembly of veneers, laminated with an adhesive, in which the grain direction of the ou
26、ter veneers and most other veneers are parallel and run in the longitudinal direction 4.2 dry conditions conditions in which the LVL attains an equilibrium moisture content not exceeding 12 % except for only a few weeks per year (e.g. ambient temperature of 20 C and relative humidity of 65 %) NOTE 1
27、 LVL, suitable for use in these conditions, is considered as suitable for use in biological-use class 1 of ISO 21887. NOTE 2 LVL, under these conditions, is appropriate for dry internal applications, excluding any extended direct exposure to water. ISO 18776:2008(E) ISO 2008 All rights reserved 3 4.
28、3 tropical-dry/humid conditions conditions in which the LVL attains an equilibrium moisture content not exceeding 18 %, except for only a few weeks per year (e.g. ambient temperature of 30 C and relative humidity of 85 %) NOTE 1 LVL, suitable for use in these conditions, is considered as suitable fo
29、r use in biological-use class 1 and class 2 of ISO 21887. NOTE 2 LVL, under these conditions, is appropriate for protected external applications (e.g. behind cladding or under roof coverings), but is also capable of resisting weather exposure for short periods (e.g. when exposed during the construct
30、ion). It is also suitable for interior situations where the service moisture condition is raised above the humidity of dry conditions. 4.4 high humidity/exterior conditions conditions leading to higher equilibrium moisture content than in tropical-dry/humid conditions or prolonged exposure to weathe
31、r NOTE LVL, suitable for use in these conditions, is considered as suitable for use in biological-use class 1, 2 and 3 of ISO 21887. 4.5 structural use load-bearing application for which predictable and reliable material structural-design properties are required 5 Materials The following characteris
32、tics shall form part of the manufacturing specifications: 5.1 Veneer 5.1.1 General The following requirements apply at the time of pressing: The species, species group, mechanical property group or predictor shall be identified. NOTE The notional veneer stiffnesses obtained via calibrated electronic
33、 or other techniques, such as sound waves, are considered as acceptable predictors. In LVL for structural use, the position of veneers in the assembly/construction shall be identified (see Annex B). 5.1.2 Species Any wood species is permitted. 5.1.3 Thickness Unless otherwise stated, veneer thicknes
34、s shall be a maximum of 6,0 mm. Other thicknesses are permitted, provided they meet the structural and serviceability requirements for the intended application. 5.1.4 Quality The minimum quality (grade) of each face, back and inner ply shall be specified in accordance with Annex A. ISO 18776:2008(E)
35、 4 ISO 2008 All rights reserved5.1.5 Jointing Edge joints parallel to the grain are permitted, either glued or unglued. End joints shall be defined in the manufacturing specification in regard to the type of joint (i.e. scarfed, crushed, butt or other) and the geometrical distribution and frequency
36、of joints. 5.2 Adhesives The adhesive, in combination with the veneers used, shall provide a bond of the strength, durability and integrity necessary to meet the requirements for the bond type as specified in Clause 6. 6 Bonding quality The bonding quality shall be established in accordance with ISO
37、 12466-1 (Chisel test) and ISO 12466-2. NOTE Awaiting a new document, specifically for LVL (ISO/AWI 10033). 7 Lay-up (arrangement of veneers) The lay-up (arrangement) of veneers within the LVL construction, including the type and frequency of end joints, shall be specified in accordance with Annex B
38、. 8 Dimensions, shape and tolerances Unless stated otherwise by the contract, dimensions and tolerances apply at a moisture content of (10 4) %. The moisture content shall be measured in accordance with ISO 16979. 8.1 Dimensions Length, width and thickness, measured in accordance with ISO 27567, sha
39、ll be specified, where: length is defined as the dimension in the direction along the grain of the majority of veneers in the LVL; width is defined as the dimension in the plane of the LVL normal to the length; thickness is defined as the dimension, through the LVL, normal to the length and width. I
40、SO 18776:2008(E) ISO 2008 All rights reserved 5Key 1 length 2 width 3 thickness 4 major grain direction Figure 1 Dimensions of LVL 8.2 Shape Requirements for twist, spring, bow, squareness of section and cupping shall be specified. Twist, spring, bow, squareness of section and cupping are defined in
41、 ISO 27567. 8.3 Tolerances Unless otherwise stated by the contract, the dimensions of LVL measured in accordance with ISO 27567 shall not differ from specified/declared dimensions, by more than the tolerances given in 8.3.1 and 8.3.2. 8.3.1 Dimensions Tolerances on dimensions are given in Table 1: T
42、able 1 Tolerances on dimensions Dimension Tolerances Thickness (t) 5 % Width (b) 1 % Length (L) 2 % 0 +ISO 18776:2008(E) 6 ISO 2008 All rights reserved8.3.2 Shape Tolerances on shape are given in Table 2: Table 2 Tolerances on shape Shape Tolerances Spring It shall not exceed 1 mm in 1 000 mm Bow It
43、 shall not exceed 1 mm in 1 000 mm Twist (F) It shall not exceed the value calculated by the following equation: twist= 3500 L b F t where L, b and t are the length, width and thickness, expressed in millimetres. Squareness of section The sides of a nominally rectangular cross-section of LVL shall n
44、ot deviate from a square by more than 1 mm in 50 mm Cupping It shall not exceed 1 mm in 100 mm 9 Determination of properties 9.1 Physical properties 9.1.1 if required, moisture content shall be determined in accordance with ISO 16979. 9.1.2 if required, density shall be determined in accordance with
45、 ISO 9427. 9.2 Mechanical properties 9.2.1 General For general purposes, if required, bending strength and modulus of elasticity (MOE) shall be determined in accordance with ISO 16978. 9.2.2 Structural applications Structural properties and capacities appropriate for the intended application shall b
46、e determined by structural testing and evaluation methods for laminated veneer lumber. For each structural LVL product, the structural properties on the edge and/or flat shall be determined as appropriate for the intended application. Table C.1 of Annex C defines properties to be determined for some
47、 specific applications. 9.3 Supplementary properties For certain applications, information on some supplementary properties shall be required. A number of these supplementary properties are listed in Annex D. On request, information on these required supplementary properties shall be produced by the
48、 supplier. Where available, the properties shall be determined in accordance with the relevant International Standards. If there is no International Standard available, the method used shall be described fully in the test report. ISO 18776:2008(E) ISO 2008 All rights reserved 7 10 Preservative and c
49、hemical treatments 10.1 Natural or confered biological durability Where LVL is foreseen to be exposed to wood-destroying biological agents, as defined in ISO 21887:2007, Table 3.1, it shall be protected naturally or by a conferred treatment for the service conditions considered. Regional or national standards may provide a list of natural durability characteristics of species. NOTE Treatment processes, involving harsh wetting and drying regimes, can cause internal
