ISO 8007-2:1999

INTERNATIONAL ISO
STANDARD 8007-2
First edition
1999-08-01
Carbonaceous materials used in the
production of aluminium — Sampling plans
and sampling from individual units —
Part 2:
Prebaked anodes
Produits carbonés utilisés pour la production de l'aluminium — Plans
d'échantillonnage et échantillonnage pour unités individuelles —
Partie 2: Anodes précuites
A
Reference number
Contents
1 Scope .1
2 Normative references .1
3 Definitions .1
4 Sampling plans for large consignments or for batches .1
4.1 General.1
4.2 Single unit of product.2
4.3 Drawing up a sampling plan based on acceptable quality level (AQL).2
4.4 Operating the sampling plan based on acceptable quality level (AQL).2
4.5 Drawing up a sampling plan based on average test values.6
5 Taking test samples from individual anodes.6
5.1 Procedure .6
5.2 Dimensions of test samples .6
5.3 Sampling points.6
6 Sampling report .9
Annex A (informative) Examples.11
©  ISO 1999
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
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Printed in Switzerland
ii
© ISO
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO technical
committees. Each member body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, governmental and non-governmental, in
liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
International Standard ISO 8007-2 was prepared by Technical Committee, ISO/TC 47, Chemistry, Subcommittee
SC 7, Aluminium oxide, cryolite, aluminium fluoride, sodium fluoride, carbonaceous products for the aluminium
industry.
ISO 8007 consists of the following parts, under the general title, Carbonaceous materials used in the production of
aluminium — Sampling plans and sampling from individual units:
 Part 1: Cathode blocks
 Part 2: Prebaked anodes
Part 3, which is in preparation, will give procedures for sampling sidewall blocks.
Annex A of this part of ISO 8007 is for information only.
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INTERNATIONAL STANDARD © ISO ISO 8007-2:1999(E)
Carbonaceous materials used in the production of aluminium —
Sampling plans and sampling from individual units —
Part 2:
Prebaked anodes
1 Scope
This part of ISO 8007 specifies procedures for the creation and execution of a sampling plan for prebaked anodes
from a large consignment or from a batch.
NOTE The term "batch" can be substituted by the term "lot" if desired.
This part of ISO 8007 also specifies the preferred locations for taking test samples from individual anodes.
Cathode blocks and prebaked anodes are considered separately. Procedures for sampling cathode blocks are
given in ISO 8007-1.
For advice on safety, the reader is referred to ISO 3165:1976, Sampling of chemical products for industrial use —
Safety in sampling.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this
part of ISO 8007. For dated references, subsequent amendments to, or revisions of, any of these publications do not
apply. However, parties to agreements based on this part of ISO 8007 are encouraged to investigate the possibility of
applying the most recent editions of the normative documents indicated below. For undated references, the latest
edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid
International Standards.
ISO 3534 (all parts), Statistics — Vocabulary and symbols.
ISO 5022:1979, Shaped refractory products — Sampling and acceptance testing.
3 Definitions
For the purposes of this part of ISO 8007, the definitions given in ISO 3534 (all parts) and ISO 5022 apply.
4 Sampling plans for large consignments or for batches
4.1 General
The sampling plan may be defined in terms of an acceptable quality level (AQL). It may be applied when the parties
concerned have agreed to do so and have therefore, by common consent, made a choice between the various
options described in this part of ISO 8007. The parties shall also agree on the various properties to be measured
(for example, density and electrical resistivity) so that the sampling plan is suitable for its ultimate purpose of
providing representative samples for subsequent testing.
© ISO
It is also possible to apply the procedures given in this part of ISO 8007 while modifying, by prior agreement
between the parties concerned, the recommended values given in the sampling plans (see Tables 1, 2, 3 and 4).
The efficiency of a sampling plan depends solely on the number of sampled units, n, whatever the size of the batch,
N, provided that n/N is less than 10 %. Tables 1, 2, 3 and 4 shall be used to determine, on the basis of the required
efficiency, what the sample size, n, shall be.
If experience shows that the quality of the manufacturer's production corresponds to the agreements, it is possible,
when batches of the same quality are frequently subjected to acceptance procedures, that a plan with lower
efficiency be chosen. This would imply the use of a smaller sample size, n.
If later experience shows that the quality of production fails to correspond to the agreements when judged against
pre-set criteria, then it is necessary to return to the original, higher efficiency, sampling plan.
Alternatively, a sampling plan may be defined in terms of average test values together with a limitation on the range
of test values instead of, or in addition to, acceptable quality levels (AQLs).
Statistical process control (SPC) or statistical quality control (SQC) charts are recommended tools when operating
the sampling plan.
4.2 Single unit of product
The single unit of product shall be agreed between seller and buyer. It may be a single prebaked anode or it may be
1 t of anodes.
4.3 Drawing up a sampling plan based on acceptable quality level (AQL)
Before the sampling plan can be drawn up from the tables, it is necessary to agree on the parameters given below:
a) The acceptable quality level, i.e. the the poorest quality that can be considered acceptable as the process
average.
b) Whether normal or tightened inspection is to be used. This is decided by studying the sampling results for the
last few batches. The rules for switching from one kind of inspection to another are given in 4.5.2.
c) The batch size, which may be the amount produced in a production batch (or lot) or, preferably, the amount
produced or received in a one-month time period.
4.4 Operating the sampling plan based on acceptable quality level (AQL)
4.4.1  Table 1 gives suitable values for the three parameters described in 4.3. Buyer and seller may replace the
recommended values with their own values if required. This shall be included in the sampling report [see 6 c)].
Table 1 — Recommended values for operating the sampling plan
Acceptable quality level (AQL) 2,5
Normal or tightened inspection Normal
Tonnes per month of production
Batch size
or
number of units of product in batch or lot
4.4.2  Refer to Table 2 and, using the agreed values from Ta
...