-50% discount* If you buy the same UNE standard in different languages. * Discount on the lower pvp.

ISO 3951-2:2013

Sampling procedures for inspection by variables — Part 2: General specification for single sampling plans indexed by acceptance quality limit (AQL) for lot-by-lot inspection of independent quality characteristics

Edition date: 2013-08-27
In Force
Available languages: French, English
Summary:

ISO 3951-2:2013 specifies an acceptance sampling system of single sampling plans for inspection by variables. It is indexed in terms of the acceptance quality limit (AQL) and is of a technical nature, aimed at users who are already familiar with sampling by variables or who have complicated requirements. (A more introductory treatment is given in ISO 3951-1.)

The objectives of the methods laid down in ISO 3951-2:2013 are to ensure that lots of an acceptable quality have a high probability of acceptance and that the probability of not accepting inferior lots is as high as practicable. This is achieved by means of the switching rules, which provide the following:

  • automatic protection to the consumer (by means of a switch to tightened inspection or discontinuation of sampling inspection) should a deterioration in quality be detected;
  • an incentive (at the discretion of the responsible authority) to reduce inspection costs (by means of a switch to a smaller sample size) should consistently good quality be achieved.

In ISO 3951-2:2013, the acceptability of a lot is either implicitly or explicitly determined from an estimate of the percentage of nonconforming items in the process, based on a random sample of items from the lot.

ISO 3951-2:2013 is intended for application to a continuing series of lots of discrete products all supplied by one producer using one production process. If there are different producers or production processes, ISO 3951-2:2013 is applied to each one separately.



ISO 3951-2: 2013 est principalement destinée aux situations suivantes:

a) lorsque la procédure de contrôle doit être appliquée à une série continue de lots de produits distincts, tous fournis par un même producteur utilisant un procédé de production unique. S'il y a plusieurs producteurs ou processus de production, cette partie de l'ISO 3951 doit s'appliquer séparément à chacun d'eux;

b) lorsque les caractéristiques-qualité des éléments du produit sont mesurables sur une échelle continue;

c) lorsque l'erreur de mesure est négligeable (c'est-à-dire que l'écart-type ne dépasse pas 10 % de l'écart-type correspondant du processus). Toutefois, des procédures sont indiquées dans l'Article 9 et l'Annexe P et permettent de tenir compte de l'erreur de mesurage quand son écart-type n'est pas négligeable;

d) lorsque la production est stable (statistiquement maîtrisée) et que les caractéristiques-qualité sont distribuées selon une loi normale ou une approximation proche d'une répartition normale;

e) En présence de plusieurs caractéristiques-qualité, elles sont indépendantes ou presque indépendantes les unes des autres;

f) lorsqu'un contrat ou une norme définit une limite de spécification inférieure L, une limite de spécification supérieure U ou les deux sur chacune des caractéristiques-qualité. S'il n'y a qu'une seule caractéristique-qualité, un individu est qualifié de conforme si sa caractéristique-qualité mesurée x satisfait à la condition appropriée parmi les suivantes:

  1. x ≥ L (c'est-à-dire que la limite de spécification inférieure n'est pas violée);
  2. x ≥ U (c'est-à-dire que la limite de spécification supérieure n'est pas violée);
  3. x ≥ L et x ≥ U (c'est-à-dire qu'aucune des limites de spécification inférieure et supérieure n'est violée).

S'il y a m caractéristiques-qualité (au moins deux) et qu'on désigne par Li et Ui respectivement les limites inférieure et supérieure de la ième caractéristique-qualité, un individu est déclaré non-conforme si une ou plusieurs de ses m caractéristiques-qualité mesurées xi ne satisfait pas à la condition appropriée parmi les suivantes:

  1. xi ≥ Li;
  2. xi ≤ Ui;
  3. xi ≥ Li et xi ≤ Ui.

Les conditions 1), 2), 4) et 5) sont des cas dits avec une limite de spécification simple et 3) et 6) sont des cas dits à limite de spécification double. Pour les limites de spécification doubles, il est fait une distinction de plus entre les contrôles combiné, séparé et complexe. S'il n'y a qu'une caractéristique-qualité, alors:

— un contrôle est dit combiné lorsqu'une même LQA s'applique à la non-conformité au-delà des deux limites,

— un contrôle est dit séparé lorsque des LQA séparées s'appliquent aux non-conformités au-delà de chacune des limites, et

— un contrôle est dit complexe lorsqu'une LQA s'applique aux non-conformités au-delà d'une limite d'importance critique et qu'une LQA moins exigeante s'applique au total des non-conformités au-delà des deux limites.

S'il y a plusieurs caractéristiques-qualité, la présente règle se généralise comme suit:

— un contrôle est dit combiné lorsque les non-conformités au-delà des deux limites d'une variable sont considérées comme étant associées à une même classe, à laquelle s'applique une LQA unique;

— un contrôle est dit séparé lorsque les non-conformités au-delà des deux limites d'une variable sont considérées comme étant associées à deux classes distinctes, à chacune desquelles s'appliquant une LQA unique;

— un contrôle est dit complexe lorsque les non-conformités au-delà de la limite la plus critique sont associées à une classe à laquelle s'applique une LQA unique, et que le total des non-conformités au-delà des deux limites est associé à une autre classe à laquelle s'applique une LQA moins exigeante.

Il est à noter que, dans le cas où il y a plusieurs caractéristiques-qualité, une non-conformité relative à plusieurs caractéristiques peut appartenir à la même classe.
ICS: 03.120.30-Application of statistical methods
CTN: ISO/TC 69/SC 5 - 49796

Standards Cancellations

Anula a ISO 3951-2:2006

Anula a ISO 3951-2:2006/Amd 1:2009

International Equivalence

Identic UNE-ISO 3951-2:2026

Identic PNE-ISO 3951-2

The book in the author's words

Ultricies magna feugiat malesuada sociosqu varius vivamus cubilia parturient, himenaeos vitae vehicula nam placerat netus urna platea, nostra rutrum felis mattis penatibus velit quisque.

Button
Frequently Asked Questions Do you have any questions about our products?
  • Standards UNE, EN, ISO, IEC, BSI, DIN, ASTM, AFNOR, IEEE, SAE
  • In addition, you can request the rules of the rest of the organizations through the e-mail normas@aenor.com
  • Technical books on paper and in electronic format (PDF, epub).

The standards can be purchased in PDF, reading or paper. The reading standards are not download files, they can only be viewed in the client area. The standards ordered on paper and some of the books in the catalogue are printed on demand. 

Check deadlines in normas@aenor.com.

The license of use is for one user and one device, if you want to reproduce the content of the standard, you must request a license that will have an additional cost. Send us your inquiry here 

The AENOR standards and books that appear in the online store can only be purchased exclusively through the website. AENOR does not have a physical store.

Purchase procedure: by clicking on "Buy" the desired products will go to the shopping cart. If there are display problems, the recommended browser is Chrome.

To formalize the purchase you must access the customer area. If you are not registered as a customer, you must fill in a form with the data along with a password and username. This will create the account.

Once the "Customer data" form has been completed, "Order in progress" will be displayed with all the items loaded in the shopping cart, their prices, taxes established in current legislation and shipping costs if applicable.

The prices of the standards and books that appear in the various sections do not include taxes or shipping costs.

AENOR promotional codes consist of alphanumeric characters and can only be applied to online purchases, received through a specific offer and for a limited time. To apply your promotional code, you just have to enter it in step 2 of 4 of the purchase process on the website and click on "apply", after you have identified yourself and chosen the payment methods. Promo codes are not cumulative.

 

  • Credit or debit card (Visa, Mastercard) and PayPal.
  • Bank transfer. If you opt for this form of payment, you must first send AENOR a copy of the transfer by email to normas@aenor.com
  • The purchase invoice can be downloaded from the customer area, in my previous orders

In the case of clients of companies based abroad, the taxpayer identification number of the corresponding country (for example, in Argentina the CUIT), must be filled in the CIF/NIF - VAT field .

  • Direct download via the website in the Customer Area. In the customer area, which can only be accessed with a password and username, the products purchased will be available for a period of fifteen days from the date of purchase, as long as the payment has been accepted. Files in digital format are protected and in no case editable. Before purchasing them, it is important that the license of use is read and accepted as a prior step to purchase.
  • Shipping by courier. Products purchased on physical media are shipped by courier. The maximum delivery time in Spanish territory, from the acceptance of the order by AENOR, is:
  •  Approximately seven working days for all standards purchased through the store in paper format.
  • Approximately three days for books purchased through the store. Stocks of paper books are limited and their offer on the website does not imply availability within the indicated period. In the event that the requested book is not available, the customer is notified of the delay in receiving the order, which will be approximately seven working days. 

For the rest of the products that are not on the website, check availability and delivery time at normas@aenor.com.

1. For digital products (PDF, Epub), once delivery has been made by direct download via the website in the Customer Area, you will not have the right to exercise your right of withdrawal.

2. For personalised products on paper, once the purchase has been made, you will not have the right to exercise your right of withdrawal.

3.  For all other paper products, you have the right to withdraw from the sale within 14 calendar days from the date of purchase. Remember that for the return it is essential that the product is in perfect condition, sealed by the packaging and preserving its original packaging. The customer will be responsible for pickup and shipping costs.

The order invoice includes shipping costs, so there is no amount to pay to the courier. Shipping costs are calculated based on both the final destination of the order and the number of products ordered. They include transport and packaging costs. Shipping costs are subject to periodic revisions. Outlet books will have free shipping costs only if the shipment is made in the Peninsula.

Destination Up to three standards and/or publications From three standards and/or publications
Peninsula 7,31€ 8,60€
Balearic Islands 18,04€ 23,34€
Canary Islands, Ceuta and Melilla  18,04€ 23,34€
Europe 59,17€ 80,07€
United States and Canada 70,07€ 96,94€
Rest of the world 91,94€ 115,91€
  • Purchases made by residents of the Member States of the European Union will be subject to the payment of VAT (value added tax).
  • ​​
  • In the case of legal persons and natural persons who, acting as entrepreneurs, are domiciled in a Member State of the European Union (except residents in Spain) and have an intra-community NIF/VAT registered in the VIES census, they will be exempt from paying VAT, being an essential condition the sending of this document by email to normas@aenor.com.
  • Purchases made in a private capacity (natural person), regardless of where they have their residence, will be subject to the payment of VAT.
  • Purchases made by entities in non-EU countries will be exempt from paying VAT, as long as they send the corresponding tax residence document by email to normas@aenor.com.
  • The sale operations will be understood to have been carried out at AENOR's registered office: Génova 6, 28004, Madrid – Spain. 

The contract for the purchase of products through this Website shall be governed by Spanish law. Any dispute arising out of or in connection with the use of the Website or such contract shall be subject to the exclusive jurisdiction of the Courts and Tribunals of Madrid.

Notwithstanding the foregoing, if you are entering into this contract as a consumer under the terms of Royal Decree 1/2007, nothing in this clause shall affect the rights that may be granted to you as such under applicable law.