ASTM B762-21

Standard Guide of Variables Sampling of Metallic and Inorganic Coatings

SIGNIFICANCE AND USE
5.1 Sampling inspection permits the estimation of the overall quality of a group of product articles through the inspection of a relatively small number of product articles drawn from the group.  
5.2 The specification of a sampling plan provides purchasers and sellers a means of identifying the minimum quality level that is considered to be satisfactory.  
5.3 Because sampling plans yield estimates of the quality of a product, the results of the inspection are subject to error. Through the selection of a sampling plan, the potential error is known and controlled.  
5.4 Sampling inspection is used when a decision must be made about what to do with a quantity of articles. This quantity may be a shipment from a supplier, articles that are ready for a subsequent manufacturing operation, or articles ready for shipment to a customer.  
5.5 In sampling inspection, a relatively small number of articles (the sample) is selected randomly from a larger number of articles (the inspection lot); the sample is inspected for conformance to the requirements placed on the articles. Based on the results, a decision is made whether or not the lot conforms to the requirements.  
5.6 Since only a portion of a production lot is inspected, the quality of the uninspected articles is not known. The possibility exists that some of the uninspected articles are nonconforming. Therefore, basic to any sampling inspection plan is the willingness of the buyer to accept lots that contain some nonconforming articles. The number of nonconforming articles in accepted lots is controlled by the size of the sample and the criteria of acceptance that are placed on the sample.  
5.7 Acceptance sampling plans are used for the following reasons:  
5.7.1 When the cost of inspection is high and the consequences of accepting a nonconforming article are not serious.  
5.7.2 When 100 % inspection is fatiguing and boring and, therefore, likely to result in errors.  
5.7.3 When inspection requires a destru...
SCOPE
1.1 This guide provides sampling plans that are intended for use in the inspection of metallic and inorganic coatings on products for the purpose of deciding whether submitted lots of coated products comply with the specifications applicable to the coating.  
1.2 The sampling plans are variables plans. In plans of this type, several articles of product are drawn from a production lot. A characteristic of the coating on the drawn articles is measured. The values obtained are used to estimate the number of articles in the lot that do not conform to a numerical limit, for example a minimum thickness. The number is compared to a maximum allowable.  
1.3 Variables plans can only be used when the characteristic of interest is measurable, the test method gives a numerical measure of the characteristic, and the specification places a numerical limit on the measured value. It is also necessary that the variation of the characteristic from article to article in a production lot be normally distributed (see Appendix X2). Each article must be tested in the same way (for example, coating thickness must be measured at the same location, see X2.7) so that the values from article to article are comparable. If one or more of these conditions are not met, a variables plan cannot be used. Instead, an attributes plan must be used. These are given in Guide B602 and Guide B697.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 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 ...

General Information

• Status: Published
• Publication Date: 30-Sep-2021
• ICS: 25.220.40 - Metallic coatings
• ICS: 25.220.99 - Other treatments and coatings
• Technical Committee: B08 - Metallic and Inorganic Coatings
• Drafting Committee: B08.10 - Test Methods

Relations

• Refers: ASTM B697-88(2010) - Standard Guide for Selection of Sampling Plans for Inspection of Electrodeposited Metallic and Inorganic Coatings
• Effective Date: 01-Apr-2010
• Refers: ASTM B602-88(2010) - Standard Test Method for Attribute Sampling of Metallic and Inorganic Coatings
• Effective Date: 01-Apr-2010
• Refers: ASTM B602-88(2005) - Standard Test Method for Attribute Sampling of Metallic and Inorganic Coatings
• Effective Date: 15-May-2005
• Refers: ASTM B697-88(2005) - Standard Guide for Selection of Sampling Plans for Inspection of Electrodeposited Metallic and Inorganic Coatings
• Effective Date: 15-May-2005
• Refers: ASTM B697-88(1999) - Standard Guide for Selection of Sampling Plans for Inspection of Electrodeposited Metallic and Inorganic Coatings
• Effective Date: 10-Nov-1999
• Refers: ASTM B602-88(1999) - Standard Test Method for Attribute Sampling of Metallic and Inorganic Coatings
• Effective Date: 10-Nov-1999

Overview

ASTM B762-21: Standard Guide of Variables Sampling of Metallic and Inorganic Coatings provides guidance for establishing sampling plans used to inspect metallic and inorganic coatings on products. The primary intent is to assess the quality and compliance of product lots by evaluating a comparatively small and randomly selected sample, rather than performing 100% inspection. This standard supports manufacturers, suppliers, and purchasers by offering controlled and statistically sound procedures to ensure that the coatings meet specified requirements, most commonly for characteristics such as coating thickness.

Key Topics

• Variables Sampling Plans: Unlike attribute plans that classify items as either conforming or nonconforming, variables plans use actual measurement data (e.g., thickness) to estimate the proportion of nonconforming items in a lot.
• Statistical Reliability: Utilizes standard deviation, mean, and factors from pre-defined tables to make statistically justified decisions about batch acceptance.
• Applicability: Variables sampling can only be used when:
  • The coating characteristic is quantifiable,
  • Inspection provides a numerical result,
  • The specification defines a numerical limit (minimum or maximum), and
  • Variation among articles follows a normal distribution.
• Nondestructive vs Destructive Testing: The standard differentiates between sample plans for nondestructive (preferred where possible) and destructive tests.
• Quality Levels: Incorporates Acceptable Quality Level (AQL), Limiting Quality Level (LQL), and Average Outgoing Quality Limit (AOQL) into sampling decisions.
• Random Sampling: Emphasizes correct randomization methods to ensure unbiased inspection and quality assessment.
• Purchaser/Supplier Agreements: Details built-in flexibility for specifying specific sampling levels and test methods as required by the contract.

Applications

ASTM B762-21 is broadly applicable across industries that require metallic or inorganic coatings, such as automotive, aerospace, electronics, and manufacturing of consumer and industrial goods. Common practical applications include:

• Incoming and Final Inspection: Assessing compliance of large production lots before shipment to customers or before next manufacturing steps.
• Cost Reduction: Enables significant cost and time savings by inspecting a statistical sample rather than every item, especially when full inspection is costly, time-consuming, or destructive.
• Quality Control: Supports ongoing process control and supplier audits by estimating process capability and overall product quality.
• Purchasing Agreements: Promotes objective, agreed-upon criteria for lot acceptance or rejection, reducing disputes and ambiguity.

This standard is essential when destructive testing is involved, or when the cost or logistics make 100% inspection impractical. It also provides methods for both known and estimated process variation, ensuring flexibility regardless of current process knowledge.

Related Standards

ASTM B762-21 references several related standards and guides, including:

• ASTM B602: Test Method for Attribute Sampling of Metallic and Inorganic Coatings (used when variables sampling is not appropriate).
• ASTM B697: Guide for Selection of Sampling Plans for Inspection of Electrodeposited Metallic and Inorganic Coatings.
• ANSI/ASQC Z1.9: Sampling Procedures and Tables for Inspection by Variables.
• ANSI/ASQC Z1.4: Sampling Procedures and Tables for Inspection by Attributes.
• MIL-STD-105 & MIL-STD-414: Military standards for attribute and variable sampling, respectively.

These related standards provide additional sampling methodologies, selection guides, or requirements for cases that fall outside the scope or conditions specified in ASTM B762-21.

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Keywords: ASTM B762-21, variables sampling, metallic coatings, inorganic coatings, sampling inspection, quality control, nondestructive testing, destructive testing, AQL, LQL, AOQL, random sampling, manufacturing standards, coating thickness, quality assurance.

Standards Content (Sample)

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.
Designation: B762 − 21
Standard Guide of
Variables Sampling of Metallic and Inorganic Coatings
This standard is issued under the fixed designation B762; 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.
1. Scope 2. Referenced Documents
1.1 This guide provides sampling plans that are intended for 2.1 ASTM Standards:
use in the inspection of metallic and inorganic coatings on B602 Test Method for Attribute Sampling of Metallic and
products for the purpose of deciding whether submitted lots of Inorganic Coatings
coated products comply with the specifications applicable to B697 Guide for Selection of Sampling Plans for Inspection
the coating. of Electrodeposited Metallic and Inorganic Coatings
2.2 ANSI Standards:
1.2 The sampling plans are variables plans. In plans of this
ANSI/ASQC Z1.9-1979 Sampling Procedures and Tables
type, several articles of product are drawn from a production
for Inspection by Variables for Percent Non-Conformance
lot. A characteristic of the coating on the drawn articles is
ANSI/ASQC Z1.4-1981 Sampling Procedures and Tables
measured.Thevaluesobtainedareusedtoestimatethenumber
for Inspection by Attributes
of articles in the lot that do not conform to a numerical limit,
2.3 Military Standards:
for example a minimum thickness. The number is compared to
MIL-STD-105 Sampling Procedures and Tables for Inspec-
a maximum allowable.
tion by Attributes
1.3 Variables plans can only be used when the characteristic
MIL-STD-414 Sampling Procedures and Tables for Inspec-
of interest is measurable, the test method gives a numerical
tion by Variables for Percent Defective
measure of the characteristic, and the specification places a
3. Terminology
numerical limit on the measured value. It is also necessary that
the variation of the characteristic from article to article in a
3.1 destructive test, n—test that destroys the tested article or
production lot be normally distributed (see Appendix X2).
makes it nonconforming to a requirement.
Each article must be tested in the same way (for example,
3.2 inspection lot, n—collection of articles of the same kind
coating thickness must be measured at the same location, see
that is submitted to inspection for acceptance or rejection as a
X2.7) so that the values from article to article are comparable.
group.
If one or more of these conditions are not met, a variables plan
cannot be used. Instead, an attributes plan must be used. These 3.3 nondestructive test, n—test that neither destroys the
are given in Guide B602 and Guide B697. tested article nor makes it nonconforming to a requirement.
1.4 This standard does not purport to address all of the 3.4 sample, n—articles randomly selected from an inspec-
safety concerns, if any, associated with its use. It is the
tion lot whose quality is used to decide whether or not the
responsibility of the user of this standard to establish appro- inspection lot is of acceptable quality.
priate safety, health, and environmental practices and deter-
3.5 standard deviation, n—measure of dispersion equal to
mine the applicability of regulatory limitations prior to use.
the square root of the mean of the squares of the deviations
1.5 This international standard was developed in accor-
from the arithmetic mean of the distribution (see 9.2.6).
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the 4. Summary of Guide
Development of International Standards, Guides and Recom-
4.1 The plans in this guide provide the same protection as
mendations issued by the World Trade Organization Technical
the attributes plans inTables 1, 2, and 3 of Guide B602 and are
Barriers to Trade (TBT) Committee.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
This guide is under the jurisdiction ofASTM Committee B08 on Metallic and Standards volume information, refer to the standard’s Document Summary page on
Inorganic Coatings and is the direct responsibility of Subcommittee B08.10 on Test the ASTM website.
Methods. Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
Current edition approved Oct. 1, 2021. Published November 2021. Originally 4th Floor, New York, NY 10036, http://www.ansi.org.
approvedin1986.Lastpreviouseditionapprovedin2016asB762 – 90(2016).DOI: Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,
10.1520/B0762-21. Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B762 − 21
TABLE 2 Level II—Sampling Plans for Nondestructive Tests,
interchangeable with them when the conditions necessary for
A
Standard Deviation Unknown
variables sampling exist. This method has no plan comparable
Inspection 50/50
to Table 4 of Guide B602, because variables plans are subject
nk AQL LQL AOQL
Lot Size Point
to an excessive probability of error when the number of
91 through 16 1.663 1.0 12 4.8 2.4
nonconformingarticlesinalotisexpectedtobeapproximately
281 through 29 1.649 1.7 10 5.0 2.6
1 % or less as it is for the Table 4 plan. Also for this reason,
comparable variables plans are not given for the smallest lot
501 through 40 1.713 1.7 8.2 4.3 2.2
sizes of Tables 1 and 2 of Guide B602. The plans of Table 4,
1 200
1 201 through 61 1.704 2.1 7.4 4.4 2.5
and Tables 1 and 2 in Guide B602 are described as Level I,
3 200
Level II, and Level III, respectively. For consistency, Table 1
3 201 through 92 1.778 2.0 5.9 3.8 2.2
and Table 2 of this guide are described as Level II since they 10 000
10 001 through 137 1.825 2.0 4.9 3.4 2.0
are comparable to Table 1 of Guide B602, and Table 3 and
35 000
Table 4 are described as Level III.
Over 35 000 223 1.893 1.9 4.0 3.0 1.9
A
The AQL, LQL, 50/50 Point, and AOQL are in percent.
4.2 The main advantage of a variables sampling plan over
an attributes plan is that fewer articles need to be inspected to
obtain the same protection. For example, a sample of 12 using
TABLE 3 Level III—Sampling Plans for Nondestructive Tests,
variables can give the same protection as a sample of 50 using
A
Standard Deviation Known
attributes.Ontheotherhand,moreexpensivetestmethodsmay
Inspection 50/50
nk AQL LQL AOQL
be required to yield the measurements required by variables
Lot Size Point
sampling.
51 through 6 1.432 1.8 18 7.6 3.8
4.3 Generally, thickness is the only characteristic of a
151 through 10 1.411 2.7 16 7.9 4.1
coating that meets the conditions of a variables plan given in
281 through 14 1.470 2.8 13 7.1 3.5
1.3.Forthatreason,theplansinthismethodaredesignedtobe
used when the specification for the characteristic in question is
501 through 23 1.492 3.3 11 6.8 3.8
1 200
aminimumvalue,whichistheusualcaseforcoatingthickness.
1 201 through 30 1.551 3.2 9.4 6.0 3.5
Variables plans can be used when the limit is a maximum and
3 200
when there are both a minimum and a maximum. Plans for 3 201 through 44 1.618 3.1 7.7 5.3 3.2
16 000
these cases are given in the references.
16 001 through 66 1.680 3.0 6.4 4.6 3.0
35 000
4.4 The sampling plans in Tables 1 and 2 of this guide are
Over 35 000 103 1.719 3.0 5.6 4.4 2.9
consideredtobestandardfornondestructivetestingandwillbe
A
The AQL, LQL, 50/50 Point, and AOQL are in percent.
used unless the buyer specifies otherwise. Tables 5 and 6 will
be used for destructive testing; these plans use smaller samples
toreducethecostofinspectionwitharesultantreductionofthe
TABLE 4 Level III—Sampling Plans for Nondestructive Tests,
A
ability to distinguish between conforming and nonconforming
Standard Deviation Unknown
lots. Inspection 50/50
nk AQL LQL AOQL
Lot Size Point
4.5 Additional variables plans are given in Appendix X3.
51 through 12 1.433 1.7 19 7.6 3.8
Alsofoundthereareinstructionsforthecalculationofplansfor 150
151 through 19 1.410 2.6 16 7.9 3.7
needs that are not covered.
281 through 29 1.470 2.8 13 7.1 3.8
501 through 48 1.494 3.3 11 6.7 3.8
1 200
TABLE 1 Level II—Sampling Plans for Nondestructive Tests, 1 201 through 66 1.551 3.2 9.4 6.0 3.5
A
Standard Deviation Known 3 200
3 201 through 102 1.618 3.1 7.7 5.3 3.2
Inspection 50/50
nk AQL LQL AOQL
16 000
Lot Size Point
16 001 through 159 1.680 3.0 6.4 4.6 3.0
91 through 7 1.664 1.1 12 4.8 2.4
35 000
Over 35 000 248 1.717 3.0 5.6 4.3 2.9
281 through 12 1.649 1.7 10 5.0 2.6
A
The AQL, LQL, 50/50 Point, and AOQL are in percent.
501 through 16 1.712 1.7 8.2 4.4 2.3
1 200
1 201 through 25 1.704 2.1 7.4 4.4 2.5
3 200
3 201 through 36 1.778 2.0 5.9 3.8 2.2
5. Significance and Use
10 000
10 001 through 52 1.829 2.0 4.9 3.4 2.1
5.1 Sampling inspection permits the estimation of the over-
35 000
all quality of a group of product articles through the inspection
Over 35 000 82 1.893 1.9 4.0 2.9 1.9
A of a relatively small number of product articles drawn from the
The AQL, LQL, 50/50 Point, and AOQL are in percent.
group.
B762 − 21
TABLE 5 Sampling Plans for Destructive Tests, Standard
is calculated (see 9.3). If this number equals or exceeds the
A
Deviation Known
specified minimum, the inspection lot conforms to the require-
50/50
ments. If it is less, the lot does not conform. If the standard
Inspection Lot Size nk AQL LQL
Point
deviationoftheprocessisnotknown,thestandarddeviationof
26 through 1 200 5 1.262 2.3 25 10
the sample is calculated and used.
1 201 through 35 000 10 1.411 2.7 16 7.9
Over 35 000 14 1.519 2.5 12 6.5
5.9 Theuseofasamplingplaninvolvesthebalancingofthe
A
The AQL, LQL, and 50/50 Point are in percent.
costs of inspection against the consequences of accepting an
undesirablenumberofnonconformingarticles.Thereisalways
a risk that a random sample will not describe correctly the
TABLE 6 Sampling Plans for Destructive Tests, Standard
A
characteristics of the lot from which it is drawn, and that an
Deviation Unknown
unacceptable lot will be accepted or an acceptable lot will be
50/50
Inspection Lot Size nk AQL LQL
Point
rejected. The larger the sample, the smaller this risk but the
26 through 1 200 9 1.181 2.8 27 12
larger the cost of inspection.
1 201 through 35 000 19 1.412 2.5 16 7.9
Over 35 000 34 1.497 2.8 12 6.7
5.10 To understand the risks, consider that if every article in
A
The AQL, LQL, and 50/50 Point are in percent.
an inspection lot conforms to its requirements, every article in
the sample will conform also. Such lots will be accepted (Note
1). If only a few articles in an inspection lot are
nonconforming,thesampleprobablywillindicatethatthelotis
5.2 The specification of a sampling plan provides purchas-
acceptable; but there is a small probability that the sample will
ers and sellers a means of identifying the minimum quality
indicate that the lot is unacceptable. The larger the proportion
level that is considered to be satisfactory.
of nonconforming articles in an inspection lot, the more likely
it will be that the sample will indicate that the lot is unaccept-
5.3 Because sampling plans yield estimates of the quality of
able. If every article in an inspection lot is nonconforming, a
a product, the results of the inspection are subject to error.
sample will always indicate that the lot is unacceptable.
Through the selection of a sampling plan, the potential error is
known and controlled.
NOTE 1—Throughout this method, it is assumed that no mistakes are
5.4 Sampling inspection is used when a decision must be made in sampling, measurement, and calculation.
madeaboutwhattodowithaquantityofarticles.Thisquantity
5.11 The probability of accepting an inspection lot that
may be a shipment from a supplier, articles that are ready for
contains nonconforming items is often described in terms of
a subsequent manufacturing operation, or articles ready for
theAcceptable Quality Level (AQL) and the Limiting Quality
shipment to a customer.
Level (LQL).TheAQLis the quality level that is considered to
5.5 In sampling inspection, a relatively small number of
be acceptable. The LQL is a quality level that is considered to
articles(thesample)isselectedrandomlyfromalargernumber be barely tolerable.Asampling plan is selected that has a high
of articles (the inspection lot); the sample is inspected for
probability of accepting lots of AQL quality and of rejecting
conformance to the requirements placed on the articles. Based lots of LQL quality. In this method, the AQL given for a
on the results, a decision is made whether or not the lot
sampling plan is the quality level of lots (expressed as the
conforms to the requirements. percentage of nonconforming articles) that have a 95 % prob-
ability of being accepted. The LQL is the quality level of lots
5.6 Since only a portion of a production lot is inspected, the
that have a 10 % probability of being accepted or, in other
qualityoftheuninspectedarticlesisnotknown.Thepossibility
words, a 90 % probability of being rejected. The tables in this
exists that some of the uninspected articles are nonconforming.
methodgivetheAQLandLQLofeachplan.Theyalsogivethe
Therefore, basic to any sampling inspection plan is the will-
50/50 point, the quality level of a lot that is just as likely to be
ingness of the buyer to accept lots that contain some noncon-
accepted as rejected.
forming articles. The number of nonconforming articles in
accepted lots is controlled by the size of the sample and the
5.12 The disposition of nonconforming inspection lots is
criteria of acceptance that are placed on the sample.
beyond the scope of this method because, depending on the
circumstances, lots may be returned to the supplier, kept and
5.7 Acceptance sampling plans are used for the following
used, put to a different use, scrapped, reworked, or dealt with
reasons:
in some other way. An alternative is rectifying inspection in
5.7.1 When the cost of inspection is high and the conse-
which rejected lots are screened and used.
quences of accepting a nonconforming article are not serious.
5.7.2 When 100 % inspection is fatiguing and boring and,
5.13 In rectifying inspection, when an inspection lot is
therefore, likely to result in errors.
rejected, all of the articles in the lot are inspected and
5.7.3 When inspection requires a destructive test, sampling
nonconforming ones are removed. They may be replaced with
inspection must be used.
conforming articles. The now 100 % conforming lot is ac-
5.8 In acceptance sampling by variables, the coating char- cepted.With this practice, the average quality level for a series
acteristic of each article in the sample is measured. Using the of lots taken as a whole will be better because of the addition
arithmetic mean of these values, the standard deviation of the of the 100 % conforming lots. When the incoming lots are of a
process, and the factor k that is found in the Tables, a number good quality level, the average quality level of a series of lots
B762 − 21
will be even better when the rejected lots are screened and 8. Sampling
resubmitted. When incoming lots are of a poor quality level,
8.1 General—Asample shall be selected randomly from the
the average quality of a series of accepted lots will again be
inspection lot. If the test method to be used is nondestructive,
good because many of the incoming lots will be rejected and
the sample size shall be that directed in 8.2. If the test method
upgraded. At intermediate quality levels of incoming lots, the
is destructive, the sample size shall be that directed in 8.3.
average quality level of a series of accepted lots will again be
8.2 Nondestructive Tests—For nondestructive testing, the
improved, but it will not be improved as much as in either of
size of the sample shall be that specified for the sampling plan
the above cases; and there will be an intermediate quality level
level that is required by the purchaser. The sampling plans are
where the degree of improvement is the least. This improved
given for Level II in Tables 1 and 2 and for Level III in Tables
quality level is called the Average Outgoing Quality Limit
3 and 4. If the purchaser does not specify the level, Level II
(AOQL). It is the worst condition that can occur under
shall be used. The plans in Table 1 and Table 3 shall be used
rectifying inspection. The tables give theAOQLfor each plan.
when the standard deviation of the coating process is known.
There is no AOQL for the plans used with destructive tests
Tables 1 and 2 plans shall be used when the standard deviation
because destructive tests cannot be used to screen rejected lots.
is not known and must be estimated from the sample values.
NOTE 2—TheAOQLs given in the tables are strictly correct only when
8.3 Destructive Tests—For destructive testing, the size of
thesampleissmallwithrespecttothelot.Ifthisisnotthecase,thecorrect
the sample shall be that specified in Table 5 when the standard
AOQL will be smaller than the tabulated value. The correct values are
obtained by multiplying the tabulated values by the following equation:
deviation of the process is known and Table 6 when it is not
known.
1 2 sample size/lot size (1)
8.4 The sample shall be drawn randomly from the inspec-
5.14 Rectifying inspection will substantially increase the
tion lot, that is, in a manner that ensures each article an equal
cost of inspection if the incoming lots are much worse than
chance of being selected regardless of other considerations
AQL quality.
such as location in the inspection lot, appearance, quality,
5.15 Rectifying inspection is used only when required by
location on a fixture during coating, and chronological rela-
the purchaser.
tionship to the other articles. Random sampling procedures are
given in the Appendixes.
6. Ordering Information
9. Calculations
6.1 Unless otherwise specified by the purchaser, the sam-
pling plans given in Tables 1 and 2 will be used for nonde-
9.1 Calculate the arithmetic mean of the measured charac-
structive testing, and the plans given in Tables 5 and 6 for
teristic by adding the values obtained for the articles and
destructive testing.
dividing the number of articles that were tested using the
following equation:
6.2 Wheneitheranondestructiveoradestructivetestcanbe
n
used to inspect an article for conformance to a particular
X
requirement, the purchaser should specify which test is to be ( i
i51
¯
X 5 (2)
used. When a test is neither clearly nondestructive nor
n
destructive,thepurchasershouldspecifywhichitisconsidered
where:
to be.
¯
X = arithmetic mean of the measured values,
NOTE 3—The nature of a destructive test can be such that the tested
X = measured value,
i
article can be reclaimed, for example by stripping and reapplying the
n
= sum of the measured values, and
coating. Other tests can destroy the coating in nonessential locations, in
X
(
i
i51
which case the article can still be functional. In these instances, the
purchaser needs to decide and state whether the tests are to be considered n = number of articles tested.
destructive or nondestructive.
9.2 If the standard deviation of the coating process is
6.3 Rectifying inspection will be used only when specified
known, continue the calculations as directed in 9.3. The
by the purchaser. When rectifying inspection is used, noncon-
symbol for the standard deviation for the process is σ.Ifthe
forming articles will be replaced with conforming ones only
standard deviation for the process is not known, calculate an
when specified by the purchaser.
estimated value from the measurements obtained from the
sample as directed in 9.2.1 through 9.2.6. The symbol for this
7. Formation of Inspection Lot
estimated standard deviation is s.
9.2.1 Subtract the arithmetic mean from the first measured
7.1 An inspection lot shall be formed from articles that are
value using the following equation:
of the same kind, that have been produced to the same
specification, and that have been coated by a single supplier at
¯
X 2 X (3)
one time or at approximately the same time under essentially
9.2.2 Calculatethesquareofthedifferenceobtainedin9.2.1
identical conditions.
using the following equation:
NOTE 4—These requirements are intended to ensure that the lot is
¯
homogeneous and that variations between articles in the lot are the result
~X 2 X! (4)
only of the inherent variation of the production process (see Appendix
X1). 9.2.3 Repeat 9.2.1 and 9.2.2 for each measured value.
B762 − 21
9.2.4 Add all of the squares obtained in 9.2.2 and 9.2.3 ¯
X 2 kσ (9)
using the following equation:
or,calculatethefollowingwhenthestandarddeviationisnot
n
2 2 2 2
¯ ¯ ¯ ¯
~X 2 X! 1~X 2 X! 1…1 X 2 X 5 ~X 2 X! (5) known:
~ !
1 2 n 1
(
i51
¯
X 2 ks (10)
9.2.5 Divide the sum obtained in 9.2.4 by one less than the
number of articles that were tested using the following equa-
10. Inspection and Lot Classification
tion:
n
10.1 Inspection—Each article in the sample shall be in-
¯
~X 2 X!
( i
spected as directed in the applicable coating standard.
i51
(6)
n 2 1
10.2 Lot Classification:
9.2.6 Calculate the square root of the value obtained in
10.2.1 The number calculated in 9.3 shall be compared to
9.2.5 using Eq 6. This is standard deviation, s.
the minimum number stated in the coating specification. If the
n
numberin9.3equalsorexceedsthespecifiedminimum,thelot
¯
~X 2 X!
( i
conforms to the requirements. If it is less than the specified
i51
s 5 (7)
!
minimum, the lot does not conform.
n 2 1
NOTE 5—The following equation can also be used:
10.2.2 Whenspecifiedbythepurchaser,nonconforminglots
shall be 100 % inspected, and nonconforming articles shall be
~ X !
( i
removed. When required by the purchaser, the nonconforming
X 2
( i
n
s 5 (8) articles shall be replaced with conforming articles.
!
n 2 1
9.3 Usingthe kthatisinthetableandthestandarddeviation
11. Keywords
from 9.2, calculate the following number when the standard
11.1 inspection; inspection sampling; sampling procedures
deviation is known:
APPENDIXES
(Nonmandatory Information)
X1. DRAWING OF SAMPLES
X1.1 The success of acceptance sampling is totally depen- up; tails, down. If the pencil falls on column 10, line 11, and
dent on the sample being drawn from the lot at random. the coin is tails; the decision is to read down the column until
Random sampling means that the selection of an article for the 12 numbers are chosen. Take the first two digits in each group
sample is totally by chance and that every article in the lot is of five digits. The selection of random numbers is made as
equally likely to be selected. If the articles in th
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: B762 − 90 (Reapproved 2016) B762 − 21
Standard Test Method Guide of
Variables Sampling of Metallic and Inorganic Coatings
This standard is issued under the fixed designation B762; 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.
1. Scope
1.1 This test method guide provides sampling plans that are intended for use in the inspection of metallic and inorganic coatings
on products for the purpose of deciding whether submitted lots of coated products comply with the specifications applicable to the
coating.
1.2 The sampling plans are variables plans. In plans of this type, several articles of product are drawn from a production lot. A
characteristic of the coating on the drawn articles is measured. The values obtained are used to estimate the number of articles in
the lot that do not conform to a numerical limit, for example a minimum thickness. The number is compared to a maximum
allowable.
1.3 Variables plans can only be used when the characteristic of interest is measurable, the test method gives a numerical measure
of the characteristic, and the specification places a numerical limit on the measured value. It is also necessary that the variation
of the characteristic from article to article in a production lot be normally distributed (see Appendix X2). Each article must be
tested in the same way (for example, coating thickness must be measured at the same location, see X2.7) so that the values from
article to article are comparable. If one or more of these conditions are not met, a variables plan cannot be used. Instead, an
attributes plan must be used. These are given in Test Method Guide B602 and Guide B697.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.5 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.
2. Referenced Documents
2.1 ASTM Standards:
B602 Test Method for Attribute Sampling of Metallic and Inorganic Coatings
B697 Guide for Selection of Sampling Plans for Inspection of Electrodeposited Metallic and Inorganic Coatings
2.2 ANSI Standards:
ANSI/ASQC Z1.9-1979 Sampling Procedures and Tables for Inspection by Variables for Percent Non-Conformance
ANSI/ASQC Z1.4-1981 Sampling Procedures and Tables for Inspection by Attributes
This test method guide is under the jurisdiction of ASTM Committee B08 on Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee B08.10
on Test Methods.
Current edition approved Nov. 1, 2016Oct. 1, 2021. Published November 2016November 2021. Originally approved in 1986. Last previous edition approved in 20102016
as B762 – 90 (2010).(2016). DOI: 10.1520/B0762-90R16.10.1520/B0762-21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B762 − 21
2.3 Military Standards:
MIL-STD-105 Sampling Procedures and Tables for Inspection by Attributes
MIL-STD-414 Sampling Procedures and Tables for Inspection by Variables for Percent Defective
3. Definitions Terminology
3.1 destructive test—test, n—test that destroys the tested article or makes it nonconforming to a requirement.
3.2 nondestructive test—test that neither destroys the tested article nor makes it nonconforming to a requirement.
3.2 inspection lot—lot, n—collection of articles of the same kind that is submitted to inspection for acceptance or rejection as a
group.
3.3 nondestructive test, n—test that neither destroys the tested article nor makes it nonconforming to a requirement.
3.4 sample—sample, n—articles randomly selected from an inspection lot whose quality is used to decide whether or not the
inspection lot is of acceptable quality.
3.5 standard deviation—deviation, n—measure of dispersion equal to the square root of the mean of the squares of the deviations
from the arithmetic mean of the distribution (see 9.2.6).
4. Summary of Test MethodGuide
4.1 The plans in this test method guide provide the same protection as the attributes plans in Tables 1, 2, and 3 of Test Method
Guide B602 and are interchangeable with them when the conditions necessary for variables sampling exist. This method has no
plan comparable to Table 4 of Test Method Guide B602, because variables plans are subject to an excessive probability of error
when the number of nonconforming articles in a lot is expected to be approximately 1 % or less as it is for the Table 4 plan. Also
for this reason, comparable variables plans are not given for the smallest lot sizes of Tables 1 and 2 of Test Method Guide B602.
The plans of Table 4, and Tables 1 and 2 in Test Method Guide B602 are described as Level I, Level II, and Level III, respectively.
For consistency, Table 1 and Table 2 of this methodguide are described as Level II since they are comparable to Table 1 of Test
Method Guide B602, and Table 3 and Table 4 are described as Level III.
4.2 The main advantage of a variables sampling plan over an attributes plan is that fewer articles need to be inspected to obtain
the same protection. For example, a sample of 12 using variables can give the same protection as a sample of 50 using attributes.
On the other hand, more expensive test methods may be required to yield the measurements required by variables sampling.
TABLE 1 Level II—Sampling Plans for Nondestructive Tests,
A
Standard Deviation Known
Inspection 50/50
n k AQL LQL AOQL
Lot Size Point
91 through 7 1.664 1.1 12 4.8 2.4
281 through 12 1.649 1.7 10 5.0 2.6
501 through 16 1.712 1.7 8.2 4.4 2.3
1 200
1 201 through 25 1.704 2.1 7.4 4.4 2.5
3 200
3 201 through 36 1.778 2.0 5.9 3.8 2.2
10 000
10 001 through 52 1.829 2.0 4.9 3.4 2.1
35 000
Over 35 000 82 1.893 1.9 4.0 2.9 1.9
A
The AQL, LQL, 50/50 Point, and AOQL are in percent.
Available from Standardization Documents Order Desk, DODSSP, Bldg. 4, Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098.
B762 − 21
TABLE 2 Level II—Sampling Plans for Nondestructive Tests,
A
Standard Deviation Unknown
Inspection 50/50
n k AQL LQL AOQL
Lot Size Point
91 through 16 1.663 1.0 12 4.8 2.4
281 through 29 1.649 1.7 10 5.0 2.6
501 through 40 1.713 1.7 8.2 4.3 2.2
1 200
1 201 through 61 1.704 2.1 7.4 4.4 2.5
3 200
3 201 through 92 1.778 2.0 5.9 3.8 2.2
10 000
10 001 through 137 1.825 2.0 4.9 3.4 2.0
35 000
Over 35 000 223 1.893 1.9 4.0 3.0 1.9
A
The AQL, LQL, 50/50 Point, and AOQL are in percent.
TABLE 3 Level III—Sampling Plans for Nondestructive Tests,
A
Standard Deviation Known
Inspection 50/50
n k AQL LQL AOQL
Lot Size Point
51 through 6 1.432 1.8 18 7.6 3.8
151 through 10 1.411 2.7 16 7.9 4.1
281 through 14 1.470 2.8 13 7.1 3.5
501 through 23 1.492 3.3 11 6.8 3.8
1 200
1 201 through 30 1.551 3.2 9.4 6.0 3.5
3 200
3 201 through 44 1.618 3.1 7.7 5.3 3.2
16 000
16 001 through 66 1.680 3.0 6.4 4.6 3.0
35 000
Over 35 000 103 1.719 3.0 5.6 4.4 2.9
A
The AQL, LQL, 50/50 Point, and AOQL are in percent.
TABLE 4 Level III—Sampling Plans for Nondestructive Tests,
A
Standard Deviation Unknown
Inspection 50/50
n k AQL LQL AOQL
Lot Size Point
51 through 12 1.433 1.7 19 7.6 3.8
151 through 19 1.410 2.6 16 7.9 3.7
281 through 29 1.470 2.8 13 7.1 3.8
501 through 48 1.494 3.3 11 6.7 3.8
1 200
1 201 through 66 1.551 3.2 9.4 6.0 3.5
3 200
3 201 through 102 1.618 3.1 7.7 5.3 3.2
16 000
16 001 through 159 1.680 3.0 6.4 4.6 3.0
35 000
Over 35 000 248 1.717 3.0 5.6 4.3 2.9
A
The AQL, LQL, 50/50 Point, and AOQL are in percent.
4.3 Generally, thickness is the only characteristic of a coating that meets the conditions of a variables plan given in 1.3. For that
reason, the plans in this method are designed to be used when the specification for the characteristic in question is a minimum
value, which is the usual case for coating thickness. Variables plans can be used when the limit is a maximum and when there are
both a minimum and a maximum. Plans for these cases are given in the references.
B762 − 21
4.4 The sampling plans in Tables 1 and 2 of this test method guide are considered to be standard for nondestructive testing and
will be used unless the buyer specifies otherwise. Tables 5 and 6 will be used for destructive testing; these plans use smaller
samples to reduce the cost of inspection with a resultant reduction of the ability to distinguish between conforming and
nonconforming lots.
4.5 Additional variables plans are given in Appendix X3. Also found there are instructions for the calculation of plans for needs
that are not covered.
5. Significance and Use
5.1 Sampling inspection permits the estimation of the overall quality of a group of product articles through the inspection of a
relatively small number of product articles drawn from the group.
5.2 The specification of a sampling plan provides purchasers and sellers a means of identifying the minimum quality level that
is considered to be satisfactory.
5.3 Because sampling plans yield estimates of the quality of a product, the results of the inspection are subject to error. Through
the selection of a sampling plan, the potential error is known and controlled.
5.4 Sampling inspection is used when a decision must be made about what to do with a quantity of articles. This quantity may
be a shipment from a supplier, articles that are ready for a subsequent manufacturing operation, or articles ready for shipment to
a customer.
5.5 In sampling inspection, a relatively small number of articles (the sample) is selected randomly from a larger number of articles
(the inspection lot); the sample is inspected for conformance to the requirements placed on the articles. Based on the results, a
decision is made whether or not the lot conforms to the requirements.
5.6 Since only a portion of a production lot is inspected, the quality of the uninspected articles is not known. The possibility exists
that some of the uninspected articles are nonconforming. Therefore, basic to any sampling inspection plan is the willingness of the
buyer to accept lots that contain some nonconforming articles. The number of nonconforming articles in accepted lots is controlled
by the size of the sample and the criteria of acceptance that are placed on the sample.
5.7 Acceptance sampling plans are used for the following reasons:
5.7.1 When the cost of inspection is high and the consequences of accepting a nonconforming article are not serious.
5.7.2 When 100 % inspection is fatiguing and boring and, therefore, likely to result in errors.
5.7.3 When inspection requires a destructive test, sampling inspection must be used.
5.8 In acceptance sampling by variables, the coating characteristic of each article in the sample is measured. Using the arithmetic
mean of these values, the standard deviation of the process, and the factor k that is found in the Tables, a number is calculated (see
9.3). If this number equals or exceeds the specified minimum, the inspection lot conforms to the requirements. If it is less, the lot
does not conform. If the standard deviation of the process is not known, the standard deviation of the sample is calculated and used.
TABLE 5 Sampling Plans for Destructive Tests, Standard
A
Deviation Known
50/50
Inspection Lot Size n k AQL LQL
Point
26 through 1 200 5 1.262 2.3 25 10
1 201 through 35 000 10 1.411 2.7 16 7.9
Over 35 000 14 1.519 2.5 12 6.5
A
The AQL, LQL, and 50/50 Point are in percent.
B762 − 21
TABLE 6 Sampling Plans for Destructive Tests, Standard
A
Deviation Unknown
50/50
Inspection Lot Size n k AQL LQL
Point
26 through 1 200 9 1.181 2.8 27 12
1 201 through 35 000 19 1.412 2.5 16 7.9
Over 35 000 34 1.497 2.8 12 6.7
A
The AQL, LQL, and 50/50 Point are in percent.
5.9 The use of a sampling plan involves the balancing of the costs of inspection against the consequences of accepting an
undesirable number of nonconforming articles. There is always a risk that a random sample will not describe correctly the
characteristics of the lot from which it is drawn, and that an unacceptable lot will be accepted or an acceptable lot will be rejected.
The larger the sample, the smaller this risk but the larger the cost of inspection.
5.10 To understand the risks, consider that if every article in an inspection lot conforms to its requirements, every article in the
sample will conform also. Such lots will be accepted (Note 1). If only a few articles in an inspection lot are nonconforming, the
sample probably will indicate that the lot is acceptable; but there is a small probability that the sample will indicate that the lot
is unacceptable. The larger the proportion of nonconforming articles in an inspection lot, the more likely it will be that the sample
will indicate that the lot is unacceptable. If every article in an inspection lot is nonconforming, a sample will always indicate that
the lot is unacceptable.
NOTE 1—Throughout this method, it is assumed that no mistakes are made in sampling, measurement, and calculation.
5.11 The probability of accepting an inspection lot that contains nonconforming items is often described in terms of the Acceptable
Quality Level (AQL) and the Limiting Quality Level (LQL). The AQL is the quality level that is considered to be acceptable. The
LQL is a quality level that is considered to be barely tolerable. A sampling plan is selected that has a high probability of accepting
lots of AQL quality and of rejecting lots of LQL quality. In this method, the AQL given for a sampling plan is the quality level
of lots (expressed as the percentage of nonconforming articles) that have a 95 % probability of being accepted. The LQL is the
quality level of lots that have a 10 % probability of being accepted or, in other words, a 90 % probability of being rejected. The
tables in this method give the AQL and LQL of each plan. They also give the 50/50 point, the quality level of a lot that is just as
likely to be accepted as rejected.
5.12 The disposition of nonconforming inspection lots is beyond the scope of this method because, depending on the
circumstances, lots may be returned to the supplier, kept and used, put to a different use, scrapped, reworked, or dealt with in some
other way. An alternative is rectifying inspection in which rejected lots are screened and used.
5.13 In rectifying inspection, when an inspection lot is rejected, all of the articles in the lot are inspected and nonconforming ones
are removed. They may be replaced with conforming articles. The now 100 % conforming lot is accepted. With this practice, the
average quality level for a series of lots taken as a whole will be better because of the addition of the 100 % conforming lots. When
the incoming lots are of a good quality level, the average quality level of a series of lots will be even better when the rejected lots
are screened and resubmitted. When incoming lots are of a poor quality level, the average quality of a series of accepted lots will
again be good because many of the incoming lots will be rejected and upgraded. At intermediate quality levels of incoming lots,
the average quality level of a series of accepted lots will again be improved, but it will not be improved as much as in either of
the above cases; and there will be an intermediate quality level where the degree of improvement is the least. This improved quality
level is called the Average Outgoing Quality Limit (AOQL). It is the worst condition that can occur under rectifying inspection.
The tables give the AOQL for each plan. There is no AOQL for the plans used with destructive tests because destructive tests
cannot be used to screen rejected lots.
NOTE 2—The AOQLs given in the tables are strictly correct only when the sample is small with respect to the lot. If this is not the case, the correct AOQL
will be smaller than the tabulated value. The correct values are obtained by multiplying the tabulated values by the following equation:
12 sample size/lot size (1)
5.14 Rectifying inspection will substantially increase the cost of inspection if the incoming lots are much worse than AQL quality.
5.15 Rectifying inspection is used only when required by the purchaser.
B762 − 21
6. Ordering Information
6.1 Unless otherwise specified by the purchaser, the sampling plans given in Tables 1 and 2 will be used for nondestructive testing,
and the plans given in Tables 5 and 6 for destructive testing.
6.2 When either a nondestructive or a destructive test can be used to inspect an article for conformance to a particular requirement,
the purchaser should specify which test is to be used. When a test is neither clearly nondestructive nor destructive, the purchaser
should specify which it is considered to be.
NOTE 3—The nature of a destructive test can be such that the tested article can be reclaimed, for example by stripping and reapplying the coating. Other
tests can destroy the coating in nonessential locations, in which case the article can still be functional. In these instances, the purchaser needs to decide
and state whether the tests are to be considered destructive or nondestructive.
6.3 Rectifying inspection will be used only when specified by the purchaser. When rectifying inspection is used, nonconforming
articles will be replaced with conforming ones only when specified by the purchaser.
7. Formation of Inspection Lot
7.1 An inspection lot shall be formed from articles that are of the same kind, that have been produced to the same specification,
and that have been coated by a single supplier at one time or at approximately the same time under essentially identical conditions.
NOTE 4—These requirements are intended to ensure that the lot is homogeneous and that variations between articles in the lot are the result only of the
inherent variation of the production process (see Appendix X1).
8. Sampling
8.1 General—A sample shall be selected randomly from the inspection lot. If the test method to be used is nondestructive, the
sample size shall be that directed in 8.2. If the test method is destructive, the sample size shall be that directed in 8.3.
8.2 Nondestructive Tests—For nondestructive testing, the size of the sample shall be that specified for the sampling plan level that
is required by the purchaser. The sampling plans are given for Level II in Tables 1 and 2 and for Level III in Tables 3 and 4. If
the purchaser does not specify the level, Level II shall be used. The plans in Table 1 and Table 3 shall be used when the standard
deviation of the coating process is known. Tables 1 and 2 plans shall be used when the standard deviation is not known and must
be estimated from the sample values.
8.3 Destructive Tests—For destructive testing, the size of the sample shall be that specified in Table 5 when the standard deviation
of the process is known and Table 6 when it is not known.
8.4 The sample shall be drawn randomly from the inspection lot, that is, in a manner that ensures each article an equal chance
of being selected regardless of other considerations such as location in the inspection lot, appearance, quality, location on a fixture
during coating, and chronological relationship to the other articles. Random sampling procedures are given in the Appendixes.
9. Calculations
9.1 Calculate the arithmetic mean of the measured characteristic by adding the values obtained for the articles and dividing the
number of articles that were tested using the following equation:
n
X
( i
i51
¯
X 5 (2)
n
where:
X¯ = arithmetic mean of the measured values,
X = measured value,
i
n
= sum of the measured values, and
X
(
i
i51
B762 − 21
n = number of articles tested.
9.2 If the standard deviation of the coating process is known, continue the calculations as directed in 9.3. The symbol for the
standard deviation for the process is σ. If the standard deviation for the process is not known, calculate an estimated value from
the measurements obtained from the sample as directed in 9.2.1 through 9.2.6. The symbol for this estimated standard deviation
is s.
9.2.1 Subtract the arithmetic mean from the first measured value using the following equation:
¯
X 2 X (3)
9.2.2 Calculate the square of the difference obtained in 9.2.1 using the following equation:
¯
~X 2 X! (4)
9.2.3 Repeat 9.2.1 and 9.2.2 for each measured value.
9.2.4 Add all of the squares obtained in 9.2.2 and 9.2.3 using the following equation:
n
2 2 2 2
¯ ¯ ¯ ¯
~X 2 X! 1~X 2 X! 1…1 X 2 X 5 ~X 2 X! (5)
~ !
1 2 n ( 1
i51
9.2.5 Divide the sum obtained in 9.2.4 by one less than the number of articles that were tested using the following equation:
n
¯
~X 2 X!
i
(
i51
(6)
n 2 1
9.2.6 Calculate the square root of the value obtained in 9.2.5 using Eq 6. This is standard deviation, s.
n
¯
~ !
X 2 X
( i
i51
s 5 (7)
!
n 2 1
NOTE 5—The following equation can also be used:
~ X !
( i
X 2
( i
n
s 5 (8)
!
n 2 1
9.3 Using the k that is in the table and the standard deviation from 9.2, calculate the following number when the standard deviation
is known:
¯
X 2 kσ (9)
or, calculate the following when the standard deviation is not known:
¯
X 2ks (10)
10. Inspection and Lot Classification
10.1 Inspection—Each article in the sample shall be inspected as directed in the applicable coating standard.
10.2 Lot Classification:
10.2.1 The number calculated in 9.3 shall be compared to the minimum number stated in the coating specification. If the number
in 9.3 equals or exceeds the specified minimum, the lot conforms to the requirements. If it is less than the specified minimum, the
lot does not conform.
B762 − 21
10.2.2 When specified by the purchaser, nonconforming lots shall be 100 % inspected, and nonconforming articles shall be
removed. When required by the purchaser, the nonconforming articles shall be replaced with conforming articles.
11. Keywords
11.1 inspection; inspection sampling; sampling procedures
APPENDIXES
(Nonmandatory Information)
X1. DRAWING OF SAMPLES
X1.1 The success of acceptance sampling is totally dependent on the sample being drawn from the lot at random. Random
sampling means that the selection of an article for the sample is totally by chance and that every article in the lot is equally likely
...