Testing Standards for refractories

The technical suitability of the refractory products is warranted through the acquisition and interpretation of physical, chemical and technological specific properties. For this purpose, testing specifications are set down in national and international standardisation system, like BSI, AFNOR, DIN, CEN or ISO.

The derived standards-compliant results from the basis for the compilation of technical data sheet, which are then used by sales experts and customers as a sound basis for negotiation. European standards (EN) have helped with the harmonization of trade within Europe and globally.

Testing standards are of vital importance for producers, installers and end-users of the refractory products. Producers need approved and recognized standards for the evaluation of their own production and the establishment of the technical data sheets, basis of their commercial argumentation. Installers rely on the standards-compliant test results to guarantee their service to end-users. End-users with testing facilities may compare their own measurement results or the performance of the products to the technical data sheets.

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 following physical properties of refractories:

Testing method	Abb.	Definition according to EN Standards	Relevant EN Standards
Bulk Density *	BD	The ratio of the mass of the dry material of a porous body to its bulk volume, expressed in grams per cubic centimeter or in kilograms per cubic metre	EN 993-1 (dense shaped refractory), EN 1094-4 (Heat-insulating shaped refractory) EN ISO 1927-6 (unshaped refractory)
Open Porosity *	oPo	The ratio of the total volume of the open pores in a porous body to its bulk volume, expressed as a percentage of the bulk volume
Cold Crushing Strength	CCS	The maximum load per unit area, applied under specified conditions at room temperature, that a refractory product will withstand before failure occurs	EN 993-5 (dense shaped refractory), EN ISO 8895 (Heat-insulating shaped refractory), EN ISO 1927-6 (unshaped refractory)
Modulus of Rupture	MOR	The maximum stress that a prismatic test piece of specified dimensions can withstand when it is bent in three-point bending device	EN 993-10 (Dense shaped refractory) EN ISO 1927-6 (unshaped refractory)
Permanent Linear Change	PLC	The expension or contraction that remains in a refractory product that is heated to a specified temperature for a specified time and then cooled at ambient temperature	EN 993-10 (Dense shaped refractory), EN ISO 1927-6 (unshaped refractory)
Refractoriness Under Load	RUL	Measure of the behaviour of a refractory material subjected to the combined effect of load, rising temperature and time	EN ISO 1893 (Dense and insulating shaped refractory), EN ISO 1927-6 (unshaped refractory)

* both characteristics are obtained from the same testing method

The derived standards-compliant results from these five testing methods form the systematic basis for the compilation of technical data sheets (see annexes). In addition these five testing standards are essential to measure the basic intrinsic and material specific properties of refractory products as regards to their operational demands in the industry. They are basically systematically used to compare and choose a refractory product quality for a specific application. In addition, especially for unshaped products, these testing standards are applied for the assessment of a good installation procedure.