8/10/2019 TQI-25

1/7

DOCUMENT No. : T Q I 25

REV. No. 0 DATE: 15.09.1995INSPECTION INSTRUCTIONS

PAGE 1 OF 7

GUIDELINES FOR USE OF PUBLISHED ACCEPTANCE SAMPLINGPLANS FOR INSPECTION BY ATTRIBUTES

0 15.09.1995 First Issue

REV. NO. DATE BRIEF RECORD OF REVISIONS

PREPARED BY : HEAD - QA

SIGNATURE :

NAME :

APPROVED BY : CHIEF - QUALITY SERVICES

SIGNATURE :

NAME : G. SREENIVASA RAO

U N C O

N T R O

L L E D

C O P Y

8/10/2019 TQI-25

2/7

DOCUMENT No. : T Q I 25

REV. No. 0 DATE: 15.09.1995GUIDELINES FOR USE OF PUBLSHIED ACCEPTANCE SAMPLING PLANS FOR

INSPECTION BY ATTRIBUTES PAGE 2 OF 7

1.0 OBJECTIVE :

To provide guidance for selection and use of Acceptance SamplingPlans as per IS 2500 part I / 1992.

2.0 SCOPE

This covers single sampling plans for inspection by attributes of discreteitems.

3.0 DEFINITIONS

3.1 Acceptanc e Qual it y Level (AQL) :

The maximum percentage of non-conforming units that can be toleratedconsidering the customers routine use.

3.2 Sample Size (n) :

Number of units in the sample drawn at random from the lot forinspection.

3.3 Lot size (N) :

Total number of units in the lot considered for inspection.3.4 Acceptanc e Num ber (Ac ) :

Maximum number of non conforming units permitted in the sample foracceptance of the lot.

3.5 Inspection Level :

It indicates relative amount of inspection that will be performed in the lot,higher inspection level provides greater discrimination of the lot and moreprotection to the customer.

3.6 Inspection by Attributes :

Inspection whereby each unit is classified simply as conforming or non-conforming with respect to specified requirements. The inspected itemsmay be classified as O.K. or not O.K under this type of inspection.

3.7 Sampling Plan :

The specific plan which indicates the number of units in each lot which areto be inspected (sample size) and the associated criteria for determiningthe acceptability of the lot (acceptance and rejection number).

U N C O

N T R O

L L E D

C O P Y

8/10/2019 TQI-25

3/7

DOCUMENT No. : T Q I 25

REV. No. 0 DATE: 15.09.1995GUIDELINES FOR USE OF PUBLSHIED ACCEPTANCE SAMPLING PLANS FOR

INSPECTION BY ATTRIBUTES PAGE 3 OF 7

4.0 PROCEDURE

4.1 Wherever the sampling plan is specified in the contract / purchase order,the same shall be followed by the Inspection Engineer.

4.2 In case, it is not specified, the same shall be specified in the InspectionQuality Plan or by separate instructions issued by I.C to the InspectionEngineer.

4.3 The following guidelines shall be used for selecting and implementingthe sampling plans as per IS-2500-part-I / 1992.

4.3.1 Specifying AQL Level

Selection of AQL level depends on seriousness of non-conformities. Mostserious non-conformities require very small AQI, value to be assigned.Example : - 0.010, 0.015 etc.,

4.3.2 Specifying Inspection Level :

This shall be specified based on the degree of protection required, whereno level is specified, Level II may be used.

4.3.3 Determine lot size (N)4.3.4 Find the sample size code letter for the particular lot size from Table-I.

4.3.5 Selected the sampling plan from Table II A for te respective samplesize code letter and AQI specified (i.e,) read the values of sample size(n), Acceptance number (Ac) and Rejection number (Re).

4.3.6 Draw the sample from the lot, the units of sample being selected atrandom.

4.3.7 Inspect all the units in the sample and ascertain the number of non-

forming units.4.3.8 Determination of Acceptability :

If the number of non-conforming units found in the sample is equal to orless than Acceptance number (Ac), the lot shall be consideredacceptable. If the number of non-conforming units is equal to or greaterthan the rejection number, the lot shall be considered as unacceptable.

U N C O

N T R O

L L E D

C O P Y

8/10/2019 TQI-25

4/7

DOCUMENT No. : T Q I 25

REV. No. 0 DATE: 15.09.1995GUIDELINES FOR USE OF PUBLSHIED ACCEPTANCE SAMPLING PLANS FOR

INSPECTION BY ATTRIBUTES PAGE 4 OF 7

5.0 REFERENCES :

1) IS 2500 Part I 19922) ISO 2859 1 1989.

6.0 EXHIBITS :

1) Table I : Sample size code letters.

2) Table II : A single sampling plan for normal inspection.

3) Record of sampling inspection format (Typical).

U N C O

N T R O

L L E D

C O P Y

8/10/2019 TQI-25

5/7

DOCUMENT No. : T Q I 25

REV. No. 0 DATE: 15.09.1995GUIDELINES FOR USE OF PUBLSHIED ACCEPTANCE SAMPLING PLANS FOR

INSPECTION BY ATTRIBUTES PAGE 5 OF 7

SAMPLING INSPECTION RECORD

CLIENT : VENDOR :

PROJECT : P.O.No. :

CONTRACT : ITEM No. :

CODE No :

ITEM DESCRIPTION :

SPECIFICATION / DRAWING NO: REV.NO :

-----------------------------------------------------------------------------------------------------------------------LOT SIZE INSPECTION LEVEL SAMPLE SIZE

-----------------------------------------------------------------------------------------------------------------------

Sl. CHARACTERISTIC AQL ACCEPTANCE NUMBER OF ACCEPTED/ REMARKS SIGNATURENo. NUMBER (Ac) NON- REJECTED OF

CONFORMING INSPECTORUNITS

-------------------------------------------------------------------------------------------------------------------------------------

-------------------------------------------------------------------------------------------------

U N C O

N T R O

L L E D

C O P Y

8/10/2019 TQI-25

6/7

DOCUMENT No. : T Q I 25

REV. No. 0 DATE: 15.09.1995GUIDELINES FOR USE OF PUBLSHIED ACCEPTANCE SAMPLING PLANS FOR

INSPECTION BY ATTRIBUTES PAGE 6 OF 7

U N C O

N T R O

L L E D

C O P Y

8/10/2019 TQI-25

7/7

DOCUMENT No. : T Q I 25

REV. No. 0 DATE: 15.09.1995GUIDELINES FOR USE OF PUBLSHIED ACCEPTANCE SAMPLING PLANS FOR

INSPECTION BY ATTRIBUTES PAGE 7 OF 7

U N C O

N T R O

L L E D

C O P Y