ASTM B602-88(1999)

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Designation:B602 – 88(Reapproved 1999)
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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This test method gives sampling plans that are intended 2.1 ASTM Standards:
for use in the inspection of metallic and inorganic coatings for B697 GuideforSelectionofSamplingPlansforInspection
conformance to ASTM standard specifications. of Electrodeposited Metallic and Inorganic Coatings
1.2 Theplansinthistestmethod,exceptasnoted,havebeen B762 Method of Variables Sampling of Metallic and Inor-
selected from some of the single sampling plans of MIL-STD- ganic Coatings
105D.ThespecificplansselectedareidentifiedinTables1-3of 2.2 Military Standards:
this test method. The plan of Table 4, which is used for MIL–STD–105D Sampling Procedures and Tables for In-
destructive testing, is not from the Military Standard. This spection by Attributes
standard does not contain the Military Standard’s requirement MIL-STD-414 Sampling Procedures and Tables for Inspec-
for tightened inspection when the quality history of a supplier tion by Variables for Percent Defective
is unsatisfactory. 2.3 ANSI Standard:
1.3 The plans are based on inspection by attributes, that is, ANSI/ASQC Z1.9-1979 Sampling Procedures and Tables
an article of product is inspected and is classified as either for Inspection by Variables for Percent Non-
conformingtoarequirementplacedonit,orasnonconforming. Conformance
Sampling plans based on inspection by variables are given in
3. Terminology
Method B762. Variables plans are applicable when a test
yields a numerical value for a characteristic, when the speci- 3.1 Definitions:
3.1.1 destructive test—a test that destroys the tested article
fication imposes a numerical limit on the characteristic, and
when certain statistical criteria are met.These are explained in or makes it nonconforming to a requirement.
3.1.2 inspection lot—a collection of articles of the same
Method B762.
kind that is submitted to inspection for acceptance or rejection
1.4 The plans in this test method are intended to be
generally suitable. There may be instances in which tighter or as a group.
3.1.3 nondestructive test—a test that neither destroys the
looser plans or onesthat are more discriminating are desired.
AdditionalplansthatmayservetheseneedsaregiveninGuide tested article nor makes it nonconforming to a requirement.
3.1.4 sample—articles randomly selected from an inspec-
B697. Also, Guide B697 describes the nature of attribute
sampling plans and the several factors that must be considered tion lot whose quality is used to decide whether or not the
inspection lot is of acceptable quality.
in the selection of a sampling plan. More information and an
even greater selection of plans are given in MIL-STD-105D,
2 4. Significance and Use
MIL-STD-414, ANSI/ASQC Z1.9, Refs (1-7) , and in Guide
4.1 Sampling inspection permits the estimation of the over-
B697.
allqualityofagroupofproductarticlesthroughtheinspection
1.5 This standard does not purport to address all of the
of a relatively small number of product items drawn from the
safety concerns, if any, associated with its use. It is the
group.
responsibility of the user of this standard to establish appro-
4.2 The selection of a sampling plan provides purchasers
priate safety and health practices and determine the applica-
and sellers a means of identifying the minimum quality levels
bility of regulatory limitations prior to use.
that are considered to be satisfactory.
ThistestmethodisunderthejurisdictionofASTMCommitteeB-8onMetallic
and Inorganic Coatingsand is the direct responsibility of Subcommittee B08.10 on
General Test Methods. Annual Book of ASTM Standards, Vol 02.05.
Current edition approved Feb. 26, 1988. Published April 1988. Originally AvailablefromStandardizationDocumentsOrderDesk,Bldg.4SectionD,700
published as B602 – 75. Last previous edition B602–84. Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
2 5
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof Available from American National Standards Institute, 11 W. 42nd St., 13th
this Standard. Floor, New York, NY 10036.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
B602
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 5 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 5 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 5 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
Sampling is used, rather than inspection of every article in a
Accept- lot, to reduce cost.Also, some test methods are destructive, in
Sample 50/50
Inspection Lot Size ance AQL,% LQL,%
which cases sampling inspection must be used to avoid
Size Point, %
Number
destroying the lot.
1 to 25 2 0 2.5 29 68
5.2 There is always a risk that a sample will not be
26 to 1 200 13 1 2.8 13 27
representative of the lot from which it is drawn.The larger the
1201 to 35 000 32 2 2.6 8.3 16
Over 35 000 55 3 2.5 6.6 12
sample, the smaller this risk, but, the larger the cost of
A
AOQLs are not given because destructive tests cannot be used to screen
inspection. So the selection of a sampling plan involves the
rejected lots. This plan is not found in MIL-STD-105D.
balancing of the costs of inspection against the consequences
ofacceptinganundesirablenumberofnonconformingarticles.
4.3 Because sampling plans will only yield estimates of the If every article in an inspection lot conforms to its require-
quality of a product, the results of the inspection are subject to ments, every article in the sample will conform also. Such lots
error. Through the use of sampling plans, the risk of error is will always be accepted. If only a few articles in an inspection
known and controlled. lot are nonconforming, the chances are that the sample will
indicate that the lot is acceptable; but there is a small chance
5. General
that the sample will indicate that the lot is unacceptable. The
5.1 In sampling inspection, a relatively small number of larger the proportion of nonconforming articles in an inspec-
articles(thesample)isselectedrandomlyfromalargernumber tion lot, the more likely it will be that the sample will indicate
ofarticles(theinspectionlot)andisinspectedforconformance thatthelotisunacceptable.Intheextremecaseofeveryarticle
totherequirementsplacedonthearticles.Basedontheresults, inaninspectionlotbeingnonconforming,asamplewillalways
a decision is made either to accept or reject the inspection lot. indicate that the lot is unacceptable.
B602
5.3 For a given sampling plan, the chance of accepting an 6. Ordering Information
inspection lot that contains nonconforming items is often
6.1 Unless otherwise specified by the purchaser, the sam-
describedintermsoftheAcceptanceQualityLevel(AQL)and
pling plan given in Table 2 will be used for nondestructive
theLimitingQualityLevel(LQL).TheAQListhequalitylevel
testing, and the plan given in Table 4 for destructive testing.
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
level of lots that have a 10% chance of being accepted or, in
7. Formation of Inspection Lot
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
5.4 If all of the articles in a rejected inspection lot are
identical conditions.
inspected, and if nonconforming articles are removed and
replaced with conforming articles, and then if the now 100%
8. Sampling
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
NOTE 2—The nature of a destructive test can be such that the tested
Outgoing Quality Limit (AOQL). If corrective action is taken
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
or nondestructive.
of course, be used if the inspection test method is destructive.
Screeningofrejectedlotswillsubstantiallyincreasethecostof NOTE 3—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
chance of being selected regardless of other considerations
5.5 Thistestmethodcontainsfoursamplingplans.Threeare
such as its location in the inspection lot, its appearance, its
intended to be used when the inspection methods are nonde-
quality, its location on a fixture during coating, and its
structive. One of these (Table 2) is considered to be standard
chronological relationship to the other articles. Random sam-
and is the one that is followed unless the user of this method
pling procedures are given in the Annex of this test 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
9. Inspection and Lot Disposition
inspection methods are destructive. This last plan utilizes
smaller samples and so reduces the cost of inspectio
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