ASTM D6570-18a(2023)e1

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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Designation: D6570 − 18a (Reapproved 2023)
Standard Practice for
Assigning Allowable Properties for Mechanically Graded
Lumber
This standard is issued under the fixed designation D6570; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Editorial changes were made throughout in August 2023.
1. Scope D1165 Nomenclature of Commercial Hardwoods and Soft-
woods
1.1 This practice covers the methodology of grade
D1990 Practice for Establishing Allowable Properties for
qualification, assignment of design properties, and require-
Visually-Graded Dimension Lumber from In-Grade Tests
ments for the quality control of mechanically graded solid
of Full-Size Specimens
sawn lumber.
D2395 Test Methods for Density and Specific Gravity (Rela-
1.2 This practice acknowledges alternative methods for the
tive Density) of Wood and Wood-Based Materials
assignment of specific properties. These methods are assign-
D2555 Practice for Establishing Clear Wood Strength Values
ment by test, relationship to other properties, and by proce-
D2915 Practice for Sampling and Data-Analysis for Struc-
dures in other appropriate standards.
tural Wood and Wood-Based Products
D3737 Practice for Establishing Allowable Properties for
1.3 The values stated in inch-pound units are to be regarded
Structural Glued Laminated Timber (Glulam)
as standard. When there are values given in parentheses, these
D4442 Test Methods for Direct Moisture Content Measure-
are mathematical conversions to SI units that are provided for
ment of Wood and Wood-Based Materials
information only and are not considered standard.
D4761 Test Methods for Mechanical Properties of Lumber
1.4 This international standard was developed in accor-
and Wood-Based Structural Materials
dance with internationally recognized principles on standard-
D7438 Practice for Field Calibration and Application of
ization established in the Decision on Principles for the
Hand-Held Moisture Meters
Development of International Standards, Guides and Recom-
2.2 ANSI Standards:
mendations issued by the World Trade Organization Technical
ANSI A190.1 American National Standard for Wood
Barriers to Trade (TBT) Committee.
Products—Structural Glued Laminated Timber
ANSI/AWC NDS National Design Specification for Wood
2. Referenced Documents
Construction
2.1 ASTM Standards: 4
2.3 Canadian Standards Association Standard:
D9 Terminology Relating to Wood and Wood-Based Prod-
CSA O141 Canadian Standard Lumber
ucts
2.4 National Institute of Standards and Technology Stan-
D143 Test Methods for Small Clear Specimens of Timber 5
dard:
D198 Test Methods of Static Tests of Lumber in Structural
PS 20 Voluntary Product Standard, American Softwood
Sizes
Lumber Standard
D245 Practice for Establishing Structural Grades and Re-
lated Allowable Properties for Visually Graded Lumber
3. Terminology
3.1 Definitions—For definitions of terms related to wood,
refer to Terminology D9.
This practice is under the jurisdiction of ASTM Committee D07 on Wood and
is the direct responsibility of Subcommittee D07.02 on Lumber and Engineered
Wood Products. Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
Current edition approved Oct. 1, 2018. Published August 2023. Originally 4th Floor, New York, NY 10036, http://www.ansi.org.
approved in 2000. Last previous edition approved in 2018 as D6570 – 18a. DOI: Available from Canadian Standards Association (CSA), 5060 Spectrum Way,
10.1520/D6570-18AR23E01. Mississauga, ON L4W 5N6, Canada, http://www.csa.ca.
2 5
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available from National Institute of Standards and Technology (NIST), 100
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070 (http://www.nist.gov); and
Standards volume information, refer to the standard’s Document Summary page on American Lumber Standard Committee, Inc., 7470 New Technology Way, Suite F,
the ASTM website. Frederick, MD 21703 (https://alsc.org/).
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D6570 − 18a (2023)
3.2 Definitions of Terms Specific to This Standard: property is tested, that property shall be either the modulus of
3.2.1 mechanical evaluation, n—identification and appraisal rupture (MOR) or ultimate tensile stress (UTS).
of one or more physical or mechanical lumber characteristics 6.1.2 Each grade shall be qualified at each size and for each
as part of the lumber segregation process. species/species group.
6.1.3 Sampling, evaluation, and presentation of data shall be
3.2.2 mechanically graded lumber, n—solid sawn lumber
in accordance with Practice D2915.
graded by mechanical evaluation. Visual evaluation also may
be required. The material has assigned design properties and is 6.2 Qualification Samples:
manufactured for use as structural members.
6.2.1 The criteria for selecting qualification samples shall be
documented and shall be in accordance with 6.1.3.
3.2.3 qualified agency, n—an organization, hereafter re-
6.2.2 All qualification samples shall meet the visual require-
ferred to as the agency, that has trained personnel and proce-
ments established for the grade.
dures to ensure the system evaluations and grades comply with
6.2.3 The minimum sample size for estimation of strength
all applicable requirements of this practice.
properties and MOE shall be 53 specimens.
3.2.3.1 Discussion—The agency shall have no financial
6.2.4 The minimum sample size for estimation of mean or
interest in, nor shall be financially dependent upon, any single
median property values, other than MOE, shall be 30 speci-
company manufacturing the product being inspected or tested;
mens.
and shall not be owned, operated, or controlled by any such
6.2.5 When the allowable shear stress parallel to grain (F )
v
company.
or the allowable compressive stress perpendicular to grain
3.2.3.2 Discussion—The agency shall conform with the
(F ) are determined in accordance with 7.3.4 and 7.3.5,
c'
provisions for agency accreditation under the appropriate
respectively, the specific gravity of a minimum of 30 qualifi-
consensus standard.
cation test specimens shall be measured and recorded.
3.2.4 visual evaluation, n—identification and appraisal of
6.3 Qualification Test Methods:
lumber growth and manufacturing characteristics by visual
6.3.1 When mechanical and physical properties in Section 7
means as part of the lumber segregation process.
are determined by tests, the appropriate ASTM standards shall
NOTE 1—In the United States and Canada, criteria for agency accredi-
be used:
tation are contained in PS 20, ANSI A190.1, and CSA O141.
6.3.1.1 The determination of the MOE by edgewise bending
shall be in accordance with Test Methods D4761 or D198.
4. Significance and Use
6.3.1.2 The determination of the MOR by edgewise bending
4.1 The procedures described in this practice are intended to
shall be in accordance with Test Methods D4761 or D198.
be used to establish appropriate allowable unit stresses, moduli
6.3.1.3 The determination of the MOE by flat-wise bending
of elasticity, and specific gravity for mechanically graded solid
shall employ center-point loading in accordance with Test
sawn lumber. An on-going quality control program to monitor
Methods D4761 or D198.
compliance with the assigned grade properties is required.
6.3.1.4 The UTS of a sample shall be determined according
to Test Methods D4761 or D198. Whenever possible, a
5. System Requirements
minimum gage length of not less than 96 in. (2.44 m) shall be
used. When determination of the tension parallel to the grain
5.1 Mechanical Device Requirements—A mechanical de-
MOE is desired, testing shall be conducted according to the
vice used as part of the grading process shall demonstrate the
provisions of Test Methods D198.
ability to measure the mechanical or physical wood property
6.3.1.5 The determination of the ultimate shear strength
used to segregate the lumber.
parallel to grain values shall be in accordance with Test
5.2 Visual Requirements:
Methods D143.
5.2.1 Characteristics to be limited by visual evaluation shall
6.3.1.6 The determination of the compression perpendicular
be documented as part of the qualification and quality control
to grain values shall be in accordance with Test Methods D143.
procedures. Such limitations shall be part of the grade require-
6.3.1.7 Determination of the moisture content of the lumber
ments.
sample shall be in accordance with Test Methods D4442 or
5.2.2 Personnel conducting visual evaluations shall be
D7438.
qualified by the agency.
6.3.1.8 Specific gravity shall be based on weight and dimen-
sions when oven dry as specified in Test Methods D2395.
6. Criteria for Grade Qualification
Measurements shall either be taken on oven-dried specimens,
6.1 General Requirements: or at some other moisture content and the values adjusted to the
oven-dry condition.
6.1.1 A minimum of one assigned property of a grade shall
be qualified by test. The grade assignment for properties
7. Procedures for Assignment of Allowable Mechanical
qualified by test is given in 7.2.
Properties and Specific Gravity
6.1.1.1 If the modulus of elasticity (MOE) is the only
property assigned to a grade, it shall be evaluated by test.
7.1 Allowable mechanical properties and specific gravity
6.1.1.2 If both strength and MOE properties are assigned to shall be assigned using the qualification test procedures of 7.2,
a grade, a minimum of one strength property and one MOE the property correlation procedures of 7.3, or the procedures of
property shall be evaluated by test. If only one strength 7.4. These alternative procedures of 7.2 – 7.4 define the
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D6570 − 18a (2023)
maximum property values, which are permitted to be assigned 7.3.1 The methods of 7.3 permit assignment of certain
to a grade of mechanically graded lumber. allowable properties based on recognized relationships be-
tween the assigned properties. This assignment shall be in
7.1.1 Selection of the procedures specified in 7.1 to estab-
lish a value for any particular property assigned to a grade is accordance with the following procedures.
the prerogative of the grade specification author. 7.3.2 Fiber Stress in Tension Parallel to Grain:
7.1.2 The factors used in 7.2 and 7.3 apply to softwood
7.3.2.1 The maximum allowable F shall be assigned in
t
lumber. accordance with an established grade assignment model based
7.1.3 If the F is to be an assigned property, it shall be on the assigned F , which has been published by the agency.
b b
determined by the test procedures of 7.2.
7.3.2.2 In the absence of corroborative data, a maximum
7.1.4 Hardwood lumber species shall be reduced by the
F ⁄ F ratio of 0.45 shall be used.
t b
applicable factors in Practice D245, Table 8.
7.3.3 Fiber Stress in Compression Parallel to Grain:
7.1.4.1 Species containing interlocked grain shall have F ,
b 7.3.3.1 The maximum allowable F (in psi) shall be calcu-
c
F , and F evaluated by test procedures of 7.2. Sample size
lated from the following equation:
t c
selection shall consider the evidence of interlocked grain and
F 5 0.7098 F 1 2060.7 /1.9 (1)
~ !
c b
its representation in the sample.
where:
7.2 Assignment of Allowable Properties by Qualification
F = the assigned F for the grade.
b b
Tests:
7.2.1 Assignment of allowable properties by test shall
7.3.4 Shear Parallel to Grain—The F determined by a
v
follow the procedures of this section. Test results shall be
specific gravity-based model (see Appendix X1) is permitted
evaluated according to Practice D2915.
when the specific gravity is assigned in accordance with 7.2.7
7.2.1.1 Qualification tests are used to either establish allow-
or 7.3.6.
able mechanical property values for new grades or to qualify
7.3.5 Fiber Stress in Compression Perpendicular to Grain
for published grade categories.
(F )—The F determined by a specific gravity-based model
c' c'
7.2.2 Extreme Fiber Stress in Bending (F )—The fifth per-
(see Appendix X1) is permitted when specific gravity is
b
centile tolerance limit (75 % confidence) for the MOR of the
assigned in accordance with 7.2.7 or 7.3.6.
qualification sample shall equal or exceed 2.1 times the
7.3.6 Specific Gravity—It is permitted to assign specific
assigned F value.
b gravity in accordance with a model that relates grading
7.2.3 Fiber Stress in Tension Parallel to Grain (F )—The
machine measurement to specific gravity. When such a model
t
fifth percentile tolerance limit (75 % confidence) for the UTS
is used, the agency shall develop corroborative data to support
of the qualification sample shall equal or exceed 2.1 times the
the appropriateness of the assigned specific gravity.
assigned F value.
t
7.4 Assignment of Allowable Properties by Other Stan-
7.2.4 Fiber Stress in Compression Parallel to Grain (F )—
c
dards:
The fifth percentile tolerance limit (75 % confidence) for
7.4.1 The methods of 7.4 permit assignment of certain
ultimate compressive strength parallel to grain (UCS) of the
allowable properties based on procedures in the appropriate
qualification sample shall equal or exceed 1.9 times the
ASTM and ANSI standards.
assigned F value.
c
7.4.2 Shear Parallel to Grain Stress—The F shall be
v
7.2.5 Shear Stress Parallel to Grain (F )—The fifth percen-
v
assigned in accordance with the procedures of Practice D245
tile tolerance limit (75 % confidence) F for the qualification
v
for visually graded solid sawn lumber of the same species or
sample shall equal or exceed 2.1 times the assigned F value.
v
species group.
7.2.6 Modulus of Elasticity:
7.4.3 Fiber Stress in Compression Perpendicular to Grain—
7.2.6.1 The upper bound of the 95 % confidence interval of
The F shall be assigned in accordance with the procedures of
c'
the qualification sample mean MOE shall meet or exceed the
Practice D245 for visually graded solid sawn lumber of the
assigned grade MOE.
same species or species group.
7.2.6.2 For grades that include a near-minimum MOE
7.4.4 Specific Gravity—The specific gravity shall be as-
specification, the sample parametric or non-parametric point
signed as reported in ANSI/AWC NDS for visually graded
estimate as determined in accordance with Practice D2915
solid sawn lumber of the same species or species group.
shall equal or exceed the near-minimum MOE for the grade.
7.2.7 Specific Gravity (SG)—The upper bound of the 95 %
8. Minimum Allowable Property Increment
confidence interval of the qualification sample mean specific
gravity shall meet or exceed the assigned specific gravity 8.1 Allowable properties shall be rounded in accordance
value. with Table 1.
7.2.8 Fiber Stress in Compression Perpendicular to Grain
(F )—The F shall be determined by test in accordance with 9. Quality Control
c' c'
Test Methods D143, and adjusted by the procedures of Practice
9.1 A quality control program shall be developed for each
D245.
mechanical grading system. The quality control program shall
7.3 Assignment of Allowable Properties Based on Relation- delineate the respective responsibilities of the producer and the
ships: agency.
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D6570 − 18a (2023)
TABLE 1 Rounding Rules for Allowable Property Values
9.4 A quality manual shall be prepared for each production
MOE 100 000 psi facility.
F 50 psi at 1000 psi
b
9.4.1 The quality manual shall address precision and bias of
and above
25 psi below 1000 psi
calibration and measurement.
F 25 psi
t
9.4.2 The manual shall describe the inspection, sampling,
F 25 psi
c
F 5 psi
testing, and analysis to be conducted in accordance with this
c'
F 5 psi
v
practice and other applicable requirements.
SG 0.01
9.4.3 The manual shall describe corrective action to be
taken with nonconforming material.
9.2 The quality control program shall include monitoring
9.4.4 Documentation requirements of the quality control
and control of both the mechanical and visual portions of the
program shall be described in the manual, including retention
system.
and other applicable requirements.
9.2.1 The visual evaluation of the grade shall be conducted
9.4.5 The manual shall describe the individual and joint
in accordance with the applicable agency requirements.
responsibilities of the production facility and the agency.
9.2.2 The quality control program shall address the proce-
dures for quality control of the mechanical system.
10. Keywords
9.3 The quality control program shall require periodic
10.1 lumber; mechanically graded lumber; solid sawn lum-
evaluation of at least one of the assigned properties qualified in
ber; wood
6.1.1.
APPENDIXES
(Nonmandatory Information)
X1. FORMULAS FOR DETERMINING THE SHEAR STRESS PARALLEL TO GRAIN AND FIBER STRESS IN COMPRES-
SION PERPENDICULAR TO GRAIN
X1.1 Shear Stress Parallel to Grain X1.2.1.1 For Douglas Fir, Douglas Fir-Larch, Douglas Fir-
South, Hem-Fir, Southern Pine, Spruce-Pine-Fir (South), West-
X1.1.1 When qualified by measurement of the specific
ern Woods, and Western Cedars (in psi):
gravity (SG), the allowable stress in shear stress parallel to the
grain (F ) shall be calculated by a relationship between SG
F 5 2252.4 × SG 2 480 (X1.3)
v ~ !
c'
(based on oven dry weight/oven dry volume basis) and F :
v
X1.2.1.2 For Douglas Fir-Larch (N), Hem-Fir (N), and
X1.1.2 For Douglas Fir, Douglas Fir-Larch, Douglas Fir-
Spruce-Pine-Fir (in psi):
South, Hem-Fir, Southern Pine, Spruce-Pine-Fir (South), West-
F 5 2243.8 × SG 2 473.8 (X1.4)
~ !
ern Woods, and Western Cedars (in psi): c'
F 5 266 × SG 140 (X1.1)
~ !
v
X1.3 Compression Perpendicular to the Grain (F )
c'
X1.1.3 For Douglas Fir-Larch (N), Hem-Fir (N), and
(0.02-in. deformation limit)
Spruce-Pine-Fir (in psi):
X1.3.1 Refer to the appropriate agency grading rules for
F 5 ~284.8 × SG!126.6 (X1.2)
v
equations to adjust the F from a 0.04-in. deformation limit to
c'
where:
a 0.02-in. deformation limit.
SG = specific gravity (oven-dry weight/oven-dry volume
basis).
X1.2 Compression Perpendicular to the Grain (F )
c'
(0.04-in. deformation limit)
X1.2.1 When qualified by measurement of the SG, the
allowable stress shall be calculated by a relationship between
SG (based on oven dry weight/oven dry volume) and F :
c'
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D6570 − 18a (2023)
X2. EXPLANATION OF SOLID SAWN LUMBER PRODUCTS CURRENTLY PRODUCED IN THE UNITED STATES AND
CANADA BY NONDESTRUCTIVE EVALUATION
X2.1 Mechanically Graded Lumber X2.3 Machine Evaluated Lumber
X2.3.1 Machine evaluated lumber is sorted by machine and
X2.1.1 General—The process where each piece of lumber is
graded based on the following criteria, established under the
nondestructively evaluated by a machine to determine the
ALSC PS 20:
value of the sorting parameter or grading algorithm. Mechani-
X2.3.1.1 Average edge MOE equal to or greater than the
cally graded lumber also is required to meet certain visual
assigned average edge MOE.
requirements. The process assigns strength and MOE values
X2.3.1.2 At least 95 % of pieces have an edge MOE greater
based on a model that combines information from the nonde-
than 75 % of the assigned edge MOE.
structive parameter and visual characteristics. One exception is
X2.3.1.3 At least 95 % of the pieces have a MOR greater
E-rated lumber; strength values are not assigned to E-rated
than 2.1 times the assigned F .
lumber. b
X2.3.1.4 At least 95 % of the pieces have a UTS greater
than 2.1 times the assigned F .
X2.2 Machine Stress-Rated Lumber t
X2.4 E-Rated Lumber
X2.2.1 Lumber sorted by machine and graded based on the
following criteria, established under the ALSC PS 20:
X2.4.1 E-rated lumber is graded by mechanical grading into
X2.2.1.1 Average edge MOE equal to or greater than the specific MOE categories. The process assigns a long-span
assigned average edge MOE.
flat-wise MOE value and requires adherence to a fifth percen-
tile MOE value. Practice D3737, Annex A2, specifies the
X2.2.1.2 At least 95 % of pieces have an edge MOE greater
relationship between the mean and fifth percentile MOE values
than 82 % of the assigned edge MOE.
(in psi):
X2.2.1.3 At least 95 % of the pieces have a MOR greater
than 2.1 times the assigned F . MOE 5 0.955 MOE 2 0.233 (X2.1)
b 5th mean
X3. TRADITIONAL VISUAL GRADING REQUIREMENTS FOR MECHANICALLY GRADED LUMBER PRODUCED IN THE
UNITED STATES AND CANADA
X3.1 Introduction MOE level, more than one edge characteristic value is
permitted, each one forming a separate grade. For example, at
X3.1.1 Mechanically graded lumber has traditionally been,
an MOE level of 2.3, one grade may be 2.3- ⁄6 (an edge
and is currently, a performance-based product. Prior to 1990, a
characteristic ⁄6 th of the cross section is permitted) while a
common set of visual limitations was widely utilized in the
1 1
second grade may be 2.3- ⁄2 (a ⁄2 cross section characteristic is
United States and Canada. These limitations had been devel-
permitted).
oped to enhance sorting efficiency. Since 1990, some of the
regional grading agencies have developed alternate visual
X3.4 Some grade rules for MSR and E-rated lumber have
limitations keyed more closely to the performance and growth
traditionally limited edge characteristics and slope of grain in
characteristics of the species or species grouping involved.
areas of the piece not mechanically graded as follows:
This portion of the appendix is presented to document the
historical baseline requi
...