ASTM B602-88(2016)

Standard Test Method for Attribute Sampling of Metallic and Inorganic Coatings

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.
SCOPE
1.1 This test method 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, 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. 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. (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) 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) 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) AOQLs are not given because destructive tests cannot be used to screen rejected lots. This plan is not found in MIL-STD-105D.  
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 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 B762.  
1.4 The plans in this test method 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)2, 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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 31-Oct-2016
• 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

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: B602 − 88 (Reapproved 2016)
Standard Test Method 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.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
1.1 This test method gives sampling plans that are intended
for use in the inspection of metallic and inorganic coatings for
2. Referenced Documents
conformance to ASTM standard specifications.
2.1 ASTM Standards:
1.2 Theplansinthistestmethod,exceptasnoted,havebeen
B697Guide for Selection of Sampling Plans for Inspection
selected from some of the single sampling plans of MIL-STD-
of Electrodeposited Metallic and Inorganic Coatings
105D.ThespecificplansselectedareidentifiedinTables1-3of
B762Test Method of Variables Sampling of Metallic and
this test method. The plan of Table 4, which is used for
Inorganic Coatings
destructive testing, is not from the Military Standard. This
2.2 ANSI Standard:
standard does not contain the Military Standard’s requirement
ANSI/ASQC Z1.9-1979Sampling Procedures and Tables
for tightened inspection when the quality history of a supplier
for Inspection byVariables for Percent Non-Conformance
is unsatisfactory.
2.3 Military Standards:
MIL-STD-105DSampling Procedures and Tables for In-
1.3 The plans are based on inspection by attributes, that is,
spection by Attributes
an article of product is inspected and is classified as either
MIL-STD-414 Sampling Procedures and Tables for Inspec-
conformingtoarequirementplacedonit,orasnonconforming.
tion by Variables for Percent Defective
Sampling plans based on inspection by variables are given in
Test Method B762. Variables plans are applicable when a test
3. Terminology
yields a numerical value for a characteristic, when the speci-
3.1 Definitions:
fication imposes a numerical limit on the characteristic, and
3.1.1 destructive test—test that destroys the tested article or
when certain statistical criteria are met.These are explained in
makes it nonconforming to a requirement.
Test Method B762.
3.1.2 inspection lot—collection of articles of the same kind
1.4 The plans in this test method are intended to be
that is submitted to inspection for acceptance or rejection as a
generally suitable. There may be instances in which tighter or
group.
looser plans or ones that are more discriminating are desired.
AdditionalplansthatmayservetheseneedsaregiveninGuide
3.1.3 nondestructive test—test that neither destroys the
B697. Also, Guide B697 describes the nature of attribute
tested article nor makes it nonconforming to a requirement.
sampling plans and the several factors that must be considered
3.1.4 sample—articles randomly selected from an inspec-
in the selection of a sampling plan. More information and an
tion lot whose quality is used to decide whether or not the
even greater selection of plans are given in MIL-STD-105D,
inspection lot is of acceptable quality.
MIL-STD-414, ANSI/ASQC Z1.9-1979, Refs (1-7) , and in
Guide B697. 4. Significance and Use
1.5 This standard does not purport to address all of the 4.1 Sampling inspection permits the estimation of the over-
safety concerns, if any, associated with its use. It is the
allqualityofagroupofproductarticlesthroughtheinspection
responsibility of the user of this standard to establish appro- of a relatively small number of product items drawn from the
group.
1 3
ThistestmethodisunderthejurisdictionofASTMCommitteeB08onMetallic For referenced ASTM standards, visit the ASTM website, www.astm.org, or
and Inorganic Coatingsand is the direct responsibility of Subcommittee B08.10 on contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Test Methods. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Nov. 1, 2016. Published November 2016. Originally the ASTM website.
approved in 1975. Last previous edition approved in 2010 as B602–88(2010). Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
DOI: 10.1520/B0602-88R16. 4th Floor, New York, NY 10036, http://www.ansi.org.
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,
this standard. 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
B602 − 88 (2016)
A
TABLE 1 Level I—Sampling Plan for Nondestructive Tests
Acceptance
Inspection Lot Size Sample Size AQL, % 50/50 Point, % LQL, % AOQL,%
Number
B
1to 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
1to 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
1to 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
5. General
Accept-
Sample 50/50 5.1 In sampling inspection, a relatively small number of
Inspection Lot Size ance AQL,% LQL,%
Size Point, %
Number articles(thesample)isselectedrandomlyfromalargernumber
ofarticles(theinspectionlot)andisinspectedforconformance
1 to 25 2 0 2.5 29 68
26 to 1 200 13 1 2.8 13 27
totherequirementsplacedonthearticles.Basedontheresults,
1201 to 35 000 32 2 2.6 8.3 16
a decision is made either to accept or reject the inspection lot.
Over 35 000 55 3 2.5 6.6 12
Sampling is used, rather than inspection of every article in a
A
AOQLs are not given because destructive tests cannot be used to screen
lot, to reduce cost.Also, some test methods are destructive, in
rejected lots. This plan is not found in MIL-STD-105D.
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
4.2 The selection of a sampling plan provides purchasers
sample, the smaller this risk, but, the larger the cost of
and sellers a means of identifying the minimum quality levels
inspection. So the selection of a sampling plan involves the
that are considered to be satisfactory.
balancing of the costs of inspection against the consequences
4.3 Because sampling plans will only yield estimates of the ofacceptinganundesirablenumberofnonconformingarticles.
quality of a product, the results of the inspection are subject to If every article in an inspection lot conforms to its
error. Through the use of sampling plans, the risk of error is requirements, every article in the sample will conform also.
known and controlled. Such lots will always be accepted. If only a few articles in an
B602 − 88 (2016)
inspection lot are nonconforming, the chances are that the and is the one that is followed unless the user of this method
sample will indicate that the lot is acceptable; but there is a specifies either a higher quality level (Table 1) or a lower one
small chance that the sample will indicate that the lot is (Table 3). The fourth plan is intended to be used when the
unacceptable. The larger the proportion of nonconforming inspection methods are destructive. This last plan utilizes
articles in an inspection lot, the more likely it will be that the smaller samples and so reduces the cost of inspection but with
samplewillindicatethatthelotisunacceptable.Intheextreme a sacrifice in the ability to distinguish between acceptable and
case of every article in an inspection lot being nonconforming, unacceptable lots.
a sample will always indicate that the lot is unacceptable.
6. Ordering Information
5.3 For a given sampling plan, the chance of accepting an
6.1 Unless otherwise specified by the purchaser, the sam-
inspection lot that contains nonconforming items is often
pling plan given in Table 2 will be used for nondestructive
describedintermsoftheAcceptanceQualityLevel(AQL)and
testing, and the plan given in Table 4 for destructive testing.
theLimitingQualityLevel(LQL).TheAQListhequalitylevel
thatisconsideredtobeacceptable.TheLQListhequalitylevel
6.2 Wheneitheranondestructiveoradestructivetestcanbe
that is considered to be barely tolerable. A sampling plan is
used to inspect an article for conformance to a particular
selectedthatwillacceptmostsubmittedinspectionlotsofAQL
requirement, the purchaser should specify which test is to be
quality and reject most lots of LQLquality. In this test method
used.Whenatestisneitherclearlynondestructivenordestruc-
the AQL given for a sampling plan is the quality level of lots
tive (see Note 2, 8.3), the purchaser should specify which it is
(expressed as the percentage of nonconforming articles) that
considered to be.
have a 95% chance of being accepted.The LQLis the quality
7. Formation of Inspection Lot
level of lots that have a 10% chance of being accepted or, in
other words, a 90% chance of being rejected.Also given with
7.1 An inspection lot shall be formed from articles that are
eachsamplingplaninthistestmethod,isthequalitylevelofan
of the same kind, that have been produced to the same
inspectionlotthathasa50%chanceofbeingaccepted.Thisis
specification, and that have been coated by a single supplier at
called the 50/50 point.
one time or at approximately the same time under essentially
identical conditions.
5.4 If all of the articles in a rejected inspection lot are
inspected, and if nonconforming articles are removed and
8. Sampling
replaced with conforming articles, and then if the now 100%
conforming lot is resubmitted, the average quality level for a 8.1 General—A sample shall be selected from the inspec-
series of lots taken as a whole will be better because of the
tion lot. If the test method to be used is nondestructive, the
addition of the 100% conforming lot.When the incoming lots sample size shall be that directed in 8.2. If the test method is
areofagoodqualitylevel,theaveragequalitylevelofaseries
destructive, the sample size shall be that directed in 8.3.
of lots will be even better when the rejected lots are screened
8.2 Nondestructive Tests—For nondestructive testing, the
and resubmitted. When incoming lots are of a poor quality
size of the sample shall be that specified for the sampling plan
level, the average quality of a series of lots will again be good
level that is required by the purchaser. The sampling plans are
because many of the incoming lots will be rejected and
given for Level I in Table 1, for Level II in Table 2, and for
upgraded. At intermediate quality levels of incoming lots, the
LevelIIIinTable3.Ifthepurchaserdoesnotspecifythelevel,
average quality level of a series of lots will not be as good as
Level II shall be used.
in either of the above cases. The poorest average quality level
8.3 Destructive Tests—For destructive testing, the size of
that can result from the use of a given sampling plan when
the sample shall be that specified in Table 4.
screening of rejected lots is done is called the Average
Outgoing Quality Limit (AOQL). If corrective action is taken
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
by the supplier so that there is a low rejection rate of initially
coating. Other tests can destroy the coating in nonessential locations, in
supplied lots, the average quality level will be better than the
whichcasetheitemcanstillbefunctional.Intheseinstancesthepurchaser
AOQL(Note1).This100%inspectionofrejectedlotscannot,
needstodecideandstatewhetherthetestsaretobeconsidereddestructive
of course, be used if the inspection test method is destructive.
or nondestructive.
Screeningofrejectedlotswillsubstantiallyincreasethecostof
NOTE3—Theplangivenfordestructivetestsusessmallersamplesthan
the plans given for nondestructive tests. There may be cases in which
inspection if the incoming lots are much worse than AQL
destruction of even these smaller quantities is undesirable. For example,
quality. Screening is to be used only when required by the
the articles may be expensive or the inspection lot may be small. Often in
purchaser.
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
NOTE 1—The AOQLs given for Tables 1-3 are strictly correct only
specimensandtherequirementscoveringthemandtheiruseshouldbeset
when the sample is small with respect to the lot. If the sample is
forth in the applicable coating specification, purchase order, or other
consistently a significant part of the lot, the correctAOQLwill be smaller
governing document.
than the tabulated value. The correct values are obtained by multiplying
the tabulated values by:
8.4 The sample shall be drawn from the inspection lot
1−sample size/lot size
randomly,thatis,inamannerthatassureseacharticleanequal
5.5 Thistestmethodcontainsfoursamplingplans.Threeare chance of being selected regardless of other considera
...

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 2010) B602 − 88 (Reapproved 2016)
Standard Test Method 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 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, 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. 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 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
B762.
1.4 The plans in this test method 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 and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
B697 Guide for Selection of Sampling Plans for Inspection of Electrodeposited Metallic and Inorganic Coatings
B762 Test Method 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
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 that destroys the tested article or makes it nonconforming to a requirement.
This test method is under the jurisdiction of ASTM Committee B08 on Metallic and Inorganic Coatingsand is the direct responsibility of Subcommittee B08.10 on Test
Methods.
Current edition approved April 1, 2010Nov. 1, 2016. Published June 2010November 2016. Originally approved in 1975. Last previous edition approved in 20052010 as
B602 – 88 (2005).(2010). DOI: 10.1520/B0602-88R10.10.1520/B0602-88R16.
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 [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.
Available from Standardization Documents Order Desk, DODSSP, Bldg. 4, 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
B602 − 88 (2016)
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.
3.1.2 inspection lot—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 that neither destroys the tested article nor makes it nonconforming to a requirement.
3.1.4 sample—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.
B602 − 88 (2016)
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, 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
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 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.
B602 − 88 (2016)
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 pu
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