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Review and improvement of testing Standards for Refractory products

Review and improvement of testing Standards for Refractory products

Periodic Report Summary 2 - RESTAR (Review and improvement of testing Standards for Refractory products)

Project Context and Objectives:
Refractories are materials essential for all highly industrialised processes which are performed at elevated temperatures e. g. iron- and steelmaking, cement production, glass, ceramics, nonferrous metals, power production and waste incineration. Refractories have high economic importance and serve a key function for the industry in Europe. In Europe, most of refractory manufacturer are SMEs.
The technical suitability of refractory products is warranted through physical, chemical and technological materials properties, laid down in data sheets. For the purpose of obtaining those technical specifications, testing methods are described in national and international standardisation systems, like DIN, CEN or ISO. Most testing methods used for the determination of critical mechanical and physical properties of refractory products have not been thoroughly reassessed whereas in the meantime, refractory products have evolved drastically. The adequacy of current testing standards to fulfil today's requirements of the market has become highly questionable as for instance, current documents lack any statement regarding the accuracy and precision that can be expected from the test methods described.

The ReStaR project is a response to the need for a systematic investigation of the accuracy, precision, reproducibility and weaknesses of the current EN testing standards for refractories and to enhance their relevance, especially to the specific needs of the SMEs. The central objective of this project is to improve, promote and ensure the reliability, precision and efficiency of the current European testing standards which form the base of the technical data sheets for refractory products. Keeping in mind that more than 60 % of the European refractory manufacturers are SMEs and many of them operate worldwide, the economic impact of reliable and widely recognised EN testing standards should not be underestimated.

An extensive investigation of the current EN testing methods, designs of experiments and interlaboratory tests, more specifically collaborative tests, involving the major European refractory testing laboratories was the key approach. The purpose of the interlaboratory collaborative tests is to test the performance of the testing methods in the hands of the typical users. Thanks to designs of experiments and collaborative tests the reliability of the actual European standards was assessed and their shortcomings identified and subsequently improved. The expertise gained throughout the whole project not only help to strengthen the quality of the current EN testing standards but also to promote a sound base and methodology for the development of future standards for the refractory products.

To ensure a successful review of the EN testing standards and an effective dissemination of the project results a strong and broad-based cooperation between transnational partners is crucial. For this purpose, the PRE (only European SME-AG for the refractory industry) brought together the most active European testing laboratories and SMEs to conduct a large scale and in-depth study of EN testing standards. Under the umbrella of the PRE, the national SME-AG were involved in the project and actively participated in the dissemination of the results. Special attention was paid to address the interests of SMEs as potential users of standards. SMEs-associations are the natural organization to defend the interest of the SMEs.

In a nutshell:
The prime scientific objectives are to:
- figure out and improve the repeatability and reproducibility of the EN testing standards for refractory products;
- point out and optimize the practice relevant Influencing factors for the different testing methods;
- get reliable precision data for EN testing standards (reference sheets);
- bring the EN testing standards in line with the state-of-the-art;
- develop a robust investigation method for the systematic review of testing standards (guidelines and methodology).

The economic objectives for refractory producers/retailers are to:
- increase the competitiveness of the European SME refractory producers;
- improve the reliability of the EN testing standards;
- prevent the occurrence of off-specification batches and complaints from refractory (end-)users;
- demonstrate the quality of reviewed EN testing standards with the perspective to adopt European Standards in the ISO system;

The societal objectives are to:
- increase the involvement of SMEs in the standardization work;
- increase the international recognition of EN testing standards;
- promote European collaboration for the standardization work.

The European refractory industry is aware of around 65 standards to ensure the classification and characterisation of refractory products. This project focuses on the testing standards. To avoid a far too time-consuming study and dispersion of the effort into too many directions, the scope of the project is limited - in a first step - to the five most commonly used testing methods. These five testing methods are typically used to measure the six widely used critical mechanical and physical properties of refractories: Bulk Density, open Porosity, Cold Crushing Strength, Modulus of Rupture, Permanent Linear Change, Refractoriness Under Load.

Project Results:
The project ReStaR started on October 1, 2013 and is characterize by an intense experimental activity. During the second (and last) reporting period, the investigations further expand and even more statistically reliable results are achieved. Starting from screening experiments to identify relevant parameters for the investigated testing methods, being lead and involving only one institution (WP3 – first reporting period), the investigations became a cross over between the different institutions with the implementation of specifically designed study (Factorial experiments) involving at least four different RTD performers (WP4 – end of the first reporting period and beginning of the second reporting period). Then, collaborative tests (round robin test) involving eight RTD performers and two SMEs refractory producers were carried out (WP5 – second reporting period). For each testing method under investigation, samples from five kind of refractory products (dense shaped, dense unshaped, carbon bonded shaped, heat-isolating shaped and heat-isolating unshaped) were distributed within the project partners and tested according to the better defined investigated testing standards. Based on the results of these collaborative tests, precision data have be gained and support a revision process for the testing standards under examination. Of course the leadership for the investigation for one specific EN testing standard still remains on the hand of the institution starting the investigation on the EN testing standard to maintain continuity and a sound monitoring of the outcomes. In addition to allow the realisation of the scientific objectives through effective fulfilment of the technical investigation according to the work plan, the cross over investigations and collaborative tests strongly contribute to the implementation of the societal objectives: European collaboration, involvement of SMEs and an increasing international recognition of the project outcomes, and even more so, of the EN testing standards. Finally, on the basis of the expertise and results gained during the technical investigations, drafts for revised testing standards and recommendations for the investigated EN testing standards were worked out (WP6 – second reporting period).

Parallel to the experimental investigation during the first months of the project, one decisive challenge was to develop or acquire specific and proper tools for management and the exploitation of the experimental results (WP2). On one hand, a software packet was acquired by the partner FGF for the development of the project website (www.restar.eu) use to centralize project documentations and monitor the results of the investigations. On the other hand, three software packets (GUMsim, OptiVAL and PROLab) for the experimental data processing were bought from Quodata, a German SME, which operates within the scope of statistics and analytical quality assurance. A big part of the results from the investigations carried out within the WP3 and especially the experimental results from the WP4 and WP5 were analyse using these software packages.

Besides at the early stage of the project, the management procedures and governance structure were set up. Together with the European SME-AG (Cerame-Unie / PRE), the coordinator (ECREF) organised the Kick off meeting, the three project status meeting and the project final meeting. Mainly during the second reporting period, the European SME-AG and the coordinator also managed and triggered diverse dissemination actions, such as the publication of a bundle of article in the technical journal Refractories Worldforum and the organisation of a ReStaR session during the Unified International Technical Conference on Refractories (UNITECR 2015 - Fig. 1).

Potential Impact:
First of all, the management structure of the project was consolidated by selecting members of the Steering Committee, naming the works package and tasks leaders as well as confirming the coordinator and financial supervisors. The Steering Committee has held two face-to-face meeting in connection with the Kick-Off Meeting, the project status meetings and final meeting.
The Consortium agreement was signed by all the partners and submitted to the European Commission in December 2013.

During the screening experiment carried out on the five testing methods (WP3) more than 45 parameters were investigated on four different kind of refractory products (high alumina brick, carbon bonded magnesia brick, insulating brick, and alumina-silica product Medium cement castable). Each of these parameters are potential lever to improve the EN testing standards for refractory products. Part of these parameters were found to have an appraisal impact, which has been quantified at the scale of one laboratory. Other parameters proved to have a limited impact and can therefore be set as it is more suitable for the practice, especially as regards to SME capabilities.
The parameters to be deeper investigated, and especially at a much larch scale, were included into design of experiences. A total of 15 designs of experience were set up, each one specific to one testing method and one type of refractory products and base for the investigation of the WP4. A better understanding of the impact of the investigated factors was achieved and first precisions data (reproducibility and repeatability) obtained.
Out of the technical investigations from WP3 & 4, an refined testing procedure was implemented to carried out collaborative tests (round robin test) involving the eight RTD performers and the two SMEs refractory producers (WP5). For each testing method under investigation, samples from five kind of refractory products (dense shaped, dense unshaped, carbon bonded shaped, heat-isolating shaped and heat-isolating unshaped) were distributed within the project partners and tested according to the better defined investigated testing standards. Based on the results of these collaborative tests, precision data were gained (Fig. 2) and support the revision process for the testing standards under examination.

Fig. 2: Graphical representation of the round robin test results for the measurement of the Bulk Density (BD) on dense shaped refractory product and the corresponding precision data

On the basis of the expertise and results gained during the experimental investigations of the ReStaR project, drafts for revised testing standards and recommendations for the investigated EN testing standards were worked out
In the scope of the development and acquisition of specific and proper tools for management and the exploitation of the experimental results, a Website to gather datasets and easily check the project progress was set up (www.restar.eu). The project website also presents a public part for the interested public and dissemination action. In addition, meeting documents, reports, templates for recording experimental results, and submitted deliverables are available on the private part of the website.

List of Websites:
www.restar.eu

Project information

Grant agreement ID: 314884

Status

Closed project

  • Start date

    1 October 2013

  • End date

    30 September 2015

Funded under:

FP7-SME

  • Overall budget:

    € 1 615 446,20

  • EU contribution

    € 1 275 995,20

Coordinated by:

EUROPEAN CENTRE FOR REFRACTORIES gGMBH - ECREF