GB/T 7321-2017Sample preparation for testing of shaped refractory products (English PDF)

3.1 sample preparation

the process of preparing test sample from the samples

3.2 test sample

the specimen taken from samples for testing

4.1

Test sample shall be prepared from the weak position in sample quality or adopted critical position.

4.2

The position where test sample is prepared shall reflect the performance of the tested sample and be of better representative.

4.3

For large sample with complex shape or special sample difficult to be made into the test sample of the dimension required in test method standard, test sample shall be prepared through negotiation by parties concerned or according to relevant provisions.

4.4

The position where test sample is prepared shall be kept away from the parts with such defects as crack and crater on appearance.

5.1 Standard and ordinary refractory products

5.1.1 Test samples for testing of apparent porosity, volume density, compressive strength, permanent change in dimension on heating, refractoriness under load and creep in compression of dense shaped refractory products are generally taken from the corner of sample (by cutting or drilling). If the sample is small and one sample cannot meet the requirements of all preparation items, test sample can be prepared from different samples but the following conditions shall be met:

a) Test samples for testing of ambient temperature items such as apparent porosity and cold compressive strength shall be prepared from the same sample;

b) Test samples for testing of high temperature items such as refractoriness under load, creep in compression and permanent change in dimension on heating shall be prepared from the same sample.

See Figure 1 for examples for the preparation positions of test sample for apparent porosity and the like of dense shaped refractory products.

5.1.2 Test samples for testing of volume density, compressive strength and permanent change in dimension on heating of shaped thermal-insulated refractory products shall be cut from the end of sample; for standard and ordinary sample, a whole brick may be adopted as the sample for testing of volume density and thermal shock resistance. Test sample for heat conductivity coefficient is prepared according to the requirements of test method standard.

5.1.3

Test samples for testing of modulus of rupture at ambient temperature and at elevated temperature are generally cut from the pressurized surface during sample formation and the original brick face at the pressing direction during sample formation shall be reserved as the face bearing pressure during testing.

5.1.4

Test sample for abrasion resistance is generally cut from the working end of brick and the original brick face shall be reserved as the test face.

5.1.5

Test samples for testing of thermal conductivity coefficient (laser method) and thermal expansion, etc. shall be prepared at proper position of more than 15mm from the sample edge according to Chapter 4.

5.1.6

Test samples for testing of slag resistance and anti-iron corrosion resistance: drill at the working end; test sample for revolving slag resistance is prepared according to the standard requirements of test method.

5.1.7

Sample preparation principle for alkali resistance sample:

a) Alkali vapor method and alkali fusion crucible process: sample is prepared at the position required by test method and the original brick face shall be reserved as much as possible;

b) Alkali fusion buried method: three strips on the surface and at the core respectively.

5.1.8 Test sample for carbon monoxide destruction resistance

test sample is prepared at proper position and at least three original brick faces shall be reserved.

5.1.9

Sample preparation principle for thermal shock resistance sample:

a) Water quenching - rectangular brick sample: standard brick for direct test; where the sample is large, it is cut from the end and the test sample heating face shall be the original brick face;

b) Water quenching - small test sample: drill from proper position;

c) Air quenching method: prepare test sample from working end and keep the length along the working face of sample; if the length of working face is less than 114mm, it is allowed to keep along the length direction of sample; the working face of sample is the jetting face and tension face of test sample; mark well.

5.1.10

Test sample for Young’s modulus is prepared at proper position on sample.

5.1.11

For powdery or particle test samples for making chemical analysis and testing of fire resistance, true density and sulfuric acid resistance, etc., representative sample shall be prepared on each sample to crush, divide and grind it to designated size. Test sample after compressive strength testing may be adopted. If the sample surface is contaminated, it shall be treated. For the sample with obvious inconsistence at outer skin and inner layer, the representativeness of test sample shall be taken into full consideration when test sample for making chemical analysis is prepared.

5.1.12

For composite materials composed of two or more materials, test sample may be prepared at proper position according to technical standard requirements, relevant contract document, drawing requirements or through the negotiation of parties concerned.

5.1.13

If any special requirements, the sample preparation position may be determined by parties concerned through negotiation under the condition of complying with the principle of Chapter 4 and shall be noted in test report.

5.1.14

If the sample shall be reserved, except for the sample that shall be tested as a whole, each sample is generally cut into two parts, of which one for sample preparation and one as reserved sample.

5.2 Irregular and special refractory products

5.2.1

For irregular and special refractory products of which test samples can be prepared according to standard and ordinary refractory products, test sample shall be prepared according to Chapter 4 and 5.1 as much as possible.

5.2.2

For irregular and special refractory products of which test samples cannot be prepared according to the requirements, preparation of sample for testing of apparent porosity, volume density and permanent change in dimension on heating shall meet the following requirements:

a) The sample prepared from dense shaped refractory product shall have outer skin as possible at the volume of 50cm3~200cm3; the ratio of the maximum dimension of test sample to the minimum dimension shall not exceed 2:1;

b) Shaped thermal insulating refractory product is cut from the end;

c) For the product with different or asymmetrical upper and lower ends, test sample shall be prepared from working end or small end; for long product, test sample shall be prepared from the middle point.

5.2.3

Sample preparation principle for refractory products such as brick for cast steel, brick for continuous casting and air brick:

a) Refractory product for continuous casting: test samples for testing of chemical composition, volume density, apparent porosity, cold compressive strength, modulus of rupture at ambient temperature are prepared from corresponding parts according to drawing; stopper is prepared from the stopper head. Test sample for thermal shock resistance may be a whole product or cut from the product: extended nozzle is prepared from the big-opening end and submerged nozzle is prepared from the outflow end of molten steel; the integral stopper is prepared from the end of stopper head;

b) Air brick: drill at the center part after 20mm~30mm thick is cut off from the big head, or the test sample prepared by the same process may also be adopted;

c) Slide gate brick: test samples for testing of apparent porosity and volume density are prepared from casting nozzle in the width direction of brick; test sample for compressive strength is prepared from the area contacting molten steel in the length direction of brick;

d) For composite materials, test sample may be prepared at proper position according to technical standard requirements, relevant contract document, drawing requirements or through the negotiation of parties concerned.

See Figure 2 to Figure 9 for examples for the preparation positions of test sample for apparent porosity and the like of irregular and special refractory products.

5.2.4

For the sample difficult to be prepared according to the above-mentioned rules, it may be prepared through negotiation by both parties.