ASTM B602-21

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: B602 − 88 (Reapproved 2016) B602 − 21
Standard Test Method Guide for
Attribute Sampling of Metallic and Inorganic Coatings
This standard is issued under the fixed designation B602; 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 gives sampling plans that are intended for use in the inspection of metallic and inorganic coatings for
conformance to ASTM standard specifications.
1.2 The plans in this test method, guide, except as noted, have been selected from some of the single sampling plans of
MIL-STD-105D. The specific plans selected are identified in Tables 1-3 of this test method. guide. The plan of Table 4, which is
used for destructive testing, is not from the Military Standard. This standard does not contain the Military Standard’s requirement
for tightened inspection when the quality history of a supplier is unsatisfactory.
1.3 The plans are based on inspection by attributes, that is, an article of product is inspected and is classified as either conforming
to a requirement placed on it, or as nonconforming. Sampling plans based on inspection by variables are given in Test Method
Guide B762. Variables plans are applicable when a test yields a numerical value for a characteristic, when the specification imposes
a numerical limit on the characteristic, and when certain statistical criteria are met. These are explained in Test Method Guide
B762.
1.4 The plans in this test method guide are intended to be generally suitable. There may be instances in which tighter or looser
plans or ones that are more discriminating are desired. Additional plans that may serve these needs are given in Guide B697. Also,
Guide B697 describes the nature of attribute sampling plans and the several factors that must be considered in the selection of a
sampling plan. More information and an even greater selection of plans are given in MIL-STD-105D, MIL-STD-414, ANSI/ASQC
Z1.9-1979, Refs (1-7) , and in Guide B697.
1.5 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.
1.6 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:
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 1975. Last previous edition approved in 20102016
as B602 – 88 (2010).(2016). DOI: 10.1520/B0602-88R16. 10.1520/B0602-21.
The boldface numbers in parentheses refer to the list of references at the end of this standard.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B602 − 21
A
TABLE 1 Level I—Sampling Plan for Nondestructive Tests
Acceptance
Inspection Lot Size Sample Size AQL, % 50/50 Point, % LQL, % AOQL,%
Number
B
1 to 20 all 0 . . . .
21 to 280 20 0 0.26 3.4 11.0 1.8
281 to 1 200 80 1 0.44 2.1 4.8 1.1
1 201 to 3 200 125 2 0.65 2.1 4.3 1.1
3 201 to 10 000 200 3 0.68 1.8 3.3 0.97
10 001 to 35 000 315 5 0.83 1.8 2.9 1.0
Over 35 000 500 7 0.80 1.5 2.4 0.90
A
Taken from MIL-STD-105D, Single Sampling Plan, Level II, AQL = 0.65, Normal Inspection.
B
The smallest lots are 100 % inspected, and so there is no sampling risk. For this reason, there are no AQL, etc.
A
TABLE 2 Level II—Sampling Plan for Nondestructive Tests
Acceptance
Inspection Lot Size Sample Size AQL, % 50/50 Point, % LQL, % AOQL,%
Number
B
1 to 8 all 0 . . . .
9 to 90 8 0 0.64 8.3 25 4.6
91 to 280 32 1 1.1 5.2 12 2.6
281 to 500 50 2 1.7 5.3 10 2.7
501 to 1 200 80 3 1.7 4.6 8.2 2.4
1 201 to 3 200 125 5 2.1 4.5 7.4 2.5
3 201 to 10 000 200 7 2.0 3.9 5.9 2.2
10 001 to 35 000 315 10 2.0 3.4 4.9 2.1
Over 35 000 500 14 1.9 2.9 4.0 1.9
A
Taken from MIL-STD-105D, Single Sampling Plan, Level II, AQL = 1.5, Normal Inspection.
B
The smallest lots are 100 % inspected, and so there is no sampling risk. For this reason, there are no AQL, etc.
A
TABLE 3 Level III— Sampling Plan for Nondestructive Tests
Acceptance
Inspection Lot Size Sample Size AQL, % 50/50 Point, % LQL, % AOQL,%
Number
B
1 to 5 all 0 . . . .
6 to 50 5 0 1.0 12.9 37 7.4
51 to 150 20 1 1.8 8.2 18 4.2
151 to 280 32 2 2.6 8.2 16 4.3
281 to 500 50 3 2.8 7.3 13 3.9
501 to 1 200 80 5 3.3 7.1 11 4.0
1 201 to 3 200 125 7 3.2 6.1 9.4 3.6
3 201 to 16 000 200 10 3.1 7.3 7.7 3.3
16 001 to 35 000 315 14 2.9 4.7 6.4 3.0
Over 35 000 500 21 3.0 4.3 5.6 2.9
A
Taken from MIL-STD-105D, Single Sampling Plan, Level II, AQL = 2.5, Normal Inspection.
B
The smallest lots are 100 % inspected, and so there is no sampling risk. For this reason, there are no AQL, etc.
A
TABLE 4 Sampling Plan for Destructive Test
Accept-
Sample 50/50
Inspection Lot Size ance AQL,% LQL,%
Size Point, %
Number
1 to 25 2 0 2.5 29 68
26 to 1 200 13 1 2.8 13 27
1201 to 35 000 32 2 2.6 8.3 16
Over 35 000 55 3 2.5 6.6 12
A
AOQLs are not given because destructive tests cannot be used to screen
rejected lots. This plan is not found in MIL-STD-105D.
B697 Guide for Selection of Sampling Plans for Inspection of Electrodeposited Metallic and Inorganic Coatings
B762 Guide of Variables Sampling of Metallic and Inorganic Coatings
2.2 ANSI Standard:
ANSI/ASQC Z1.9-1979 Sampling Procedures and Tables for Inspection by Variables for Percent Non-Conformance
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
B602 − 21
2.3 Military Standards:
MIL-STD-105D Sampling Procedures and Tables for Inspection by Attributes
MIL-STD-414 Sampling Procedures and Tables for Inspection by Variables for Percent Defective
3. Terminology
3.1 Definitions:
3.1.1 destructive test—test, n—test that destroys the tested article or makes it nonconforming to a requirement.
3.1.2 inspection lot—lot, n—collection of articles of the same kind that is submitted to inspection for acceptance or rejection as
a group.
3.1.3 nondestructive test—test, n—test that neither destroys the tested article nor makes it nonconforming to a requirement.
3.1.4 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.
4. Significance and Use
4.1 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 items drawn from the group.
4.2 The selection of a sampling plan provides purchasers and sellers a means of identifying the minimum quality levels that are
considered to be satisfactory.
4.3 Because sampling plans will only yield estimates of the quality of a product, the results of the inspection are subject to error.
Through the use of sampling plans, the risk of error is known and controlled.
5. General
5.1 In sampling inspection, a relatively small number of articles (the sample) is selected randomly from a larger number of articles
(the inspection lot) and is inspected for conformance to the requirements placed on the articles. Based on the results, a decision
is made either to accept or reject the inspection lot. Sampling is used, rather than inspection of every article in a lot, to reduce cost.
Also, some test methods are destructive, in which cases sampling inspection must be used to avoid destroying the lot.
5.2 There is always a risk that a sample will not be representative of the lot from which it is drawn. The larger the sample, the
smaller this risk, but, the larger the cost of inspection. So the selection of a sampling plan involves the balancing of the costs of
inspection against the consequences of accepting an undesirable number of nonconforming articles. If every article in an inspection
lot conforms to its requirements, every article in the sample will conform also. Such lots will always be accepted. If only a few
articles in an inspection lot are nonconforming, the chances are that the sample will indicate that the lot is acceptable; but there
is a small chance 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. In the extreme case of every
article in an inspection lot being nonconforming, a sample will always indicate that the lot is unacceptable.
5.3 For a given sampling plan, the chance of accepting an inspection lot that contains nonconforming items is often described in
terms of the Acceptance Quality Level (AQL) and the Limiting Quality Level (LQL). The AQL is the quality level that is
considered to be acceptable. The LQL is the quality level that is considered to be barely tolerable. A sampling plan is selected that
will accept most submitted inspection lots of AQL quality and reject most lots of LQL quality. In this test 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 % chance
of being accepted. The LQL is the quality level of lots that have a 10 % chance of being accepted or, in other words, a 90 % chance
of being rejected. Also given with each sampling plan in this test method, guide, is the quality level of an inspection lot that has
a 50 % chance of being accepted. This is called the 50/50 point.
5.4 If all of the articles in a rejected inspection lot are inspected, and if nonconforming articles are removed and replaced with
Available from Standardization Documents Order Desk, DODSSP, Bldg. 4, Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098.
B602 − 21
conforming articles, and then if the now 100 % conforming lot is resubmitted, the average quality level for a series of lots taken
as a whole will be better because of the addition of the 100 % conforming lot. 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 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 lots will not be
as good as in either of the above cases. The poorest average quality level that can result from the use of a given sampling plan
when screening of rejected lots is done is called the Average Outgoing Quality Limit (AOQL). If corrective action is taken by the
supplier so that there is a low rejection rate of initially supplied lots, the average quality level will be better than the AOQL (Note
1). This 100 % inspection of rejected lots cannot, of course, be used if the inspection test method is destructive. Screening of
rejected lots will substantially increase the cost of inspection if the incoming lots are much worse than AQL quality. Screening is
to be used only when required by the purchaser.
NOTE 1—The AOQLs given for Tables 1-3 are strictly correct only when the sample is small with respect to the lot. If the sample is consistently a
significant part of the lot, the correct AOQL will be smaller than the tabulated value. The correct values are obtained by multiplying the tabulated values
by:
1 − sample size/lot size
5.5 This test method guide contains four sampling plans. Three are intended to be used when the inspection methods are
nondestructive. One of these (Table 2) is considered to be standard and is the one that is followed unless the user of this method
specifies either a higher quality level (Table 1) or a lower one (Table 3). The fourth plan is intended to be used when the inspection
methods are destructive. This last plan utilizes smaller samples and so reduces the cost of inspection but with a sacrifice in the
ability to distinguish between acceptable and unacceptable lots.
6. Ordering Information
6.1 Unless otherwise specified by the purchaser, the sampling plan given in Table 2 will be used for nondestructive testing, and
the plan given in Table 4 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 (see Note 2,
8.3), the purchaser should specify which it is considered to be.
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.
8. Sampling
8.1 General—A sample shall be selected 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 I in Table 1, for Level II in Table 2, and for Level III in Table
3. If the purchaser does not specify the level, Level II shall be used.
8.3 Destructive Tests—For destructive testing, the size of the sample shall be that specified in Table 4.
NOTE 2—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 item can still be functional. In these instances the purchaser needs to decide and
state whether the tests are to be considered destructive or nondestructive.
NOTE 3—The plan given for destructive tests uses smaller samples than the plans given for nondestructive tests. There may be cases in which destruction
of even these smaller quantities is undesirable. For example, the articles may be expensive or the inspection lot may be small. Often in such cases test
specimens are coated along with the articles and are used to represent them in the destructive tests. The permission to use test specimens and the
requirements covering them and their use should be set forth in the applicable coating specification, purchase order, or other governing document.
8.4 The sample shall be drawn from the inspection lot randomly, that is, in a manner that assures each article an equal chance of
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being selected regardless of other considerations such as its location in the inspection lot, its appearance, its quality, its location
on a fixture during coating, and its chronological relationship to the other a
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