Quality Assurance and Control

Applicable Standards

AS/NZS ISO 9001:2008 Quality Management Systems provides the basis for steel industry QA systems. Explanations of the application of these standards is beyond the scope of this handbook.

Quality Assurance for Steel and Wire

In supplying reinforcement, there are two separate levels of quality assurance.

Firstly, the quality of the raw material (steel bar and wire) is controlled during steel making and wire drawing. These materials are covered by test certificates or certificates of compliance with the appropriate standards. Each bundle or coil is tagged and identified by a serial number, from which the heat number, date of production and other details can be obtained. Delivery dockets show that the material is ‘deemed to comply’ with the relevant standard, indicating that the steel maker has a certified Quality Assurance programme in place.

On arrival at the reinforcing steel supplier’s works the material is placed in racks from which it is withdrawn as needed.

Quench and self tempered bars and micro alloy bars are not segregated because they are both Grade D500N to AS/NZS 4671.

Secondly, accuracy of fabrication must be assured by the reinforcement supplier to comply with AS3600 as well as any relevant parts of AS/NZS 4671.

Methods of Demonstrating Compliance

AS/NZS 4671 has an Appendix A which sets out the various methods by which a manufacturer can show compliance with the Standard.

These methods are described in the Standard as:

(a) Assessment by means of statistical sampling

(b) The use of a product certification scheme

(c) Assurance using the acceptability of the supplier’s quality system

(d) Other such means proposed by the manufacturer or supplier and
      acceptable to the customer

Traceability of Heat Numbers for Bars

Quality assurance procedures have removed the need for traceability to heat numbers.

Whilst large structural steel sections and plate can be readily identified back to their heat, bar and wire cannot. The latter have one big advantage - if there is any doubt about quality, a sample length can be taken and tested very easily.

Each heat of steel produces about 80 to 100 tonnes of steel, which is cast into billets of approximately 1.5 tonnes. The chemical composition of the heat is obtained by spectroscopic methods and is documented as a whole.

Each billet is rolled to one size producing 1.5 tonnes so that if 4 tonne bundles are ordered, more than one billet is required. More than one heat may be involved, but this is unusual. After rolling, the finished bar is tensile and bend tested, and the results documented.

Certificates of compliance with AS/NZS 4671 are received from the steel maker close to the time when each bundle of steel is delivered. These are cross-checked with the tag on the bundle which remains there until the bundle is opened and steel removed to the cutting bench.

After cutting, an individual bar is no longer traceable back to its originating heat or bundle. Nevertheless, a bar on site can be related back to a group of bundles of stock material released to production on a specified date, but a direct link to a specific bundle is not available.

Traceability of Wire and Mesh

In each step of the manufacturing process there are several test procedures which must be followed and each one applies to the product manufactured by that operation.

Wire is drawn from coiled rod which in turn has been rolled from the original billet. Rather than attempt full traceability for wire production, the wire making process is covered by a certificate stating that the converted material complies with AS/NZS 4671. This certificate is issued by the wire maker.

After welding the wire to make fabric, an additional assurance is given by the fabric manufacturer that the fabric complies with AS/NZS 4671.

It can be seen that traceability of wires in a sheet of fabric is not practical. A standard 2.4 metre wide sheet contains up to 25 individual longitudinal wires and 30 transverse wires, each coming from a separate coil weighing a tonne or more.

Traceability of Material

On-site traceability is the responsibility of the contractor. When performance assurance is given for the material, on-site traceability should not be required.

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