100 questions about refractories for electric furnace steelmaking (3)

Section 3 Inspection, acceptance and storage of refractory materials

21. What are the commonly used technical conditions for refractory products?

(1) Chemical composition analysis (%): MgO, Al2O3, SiO2, Cr2O3, CaO, ZrO2, C, SiC, Fe2O3. (2) Analysis of physical properties: % porosity, bulk density g/cm3, compressive strength Mpa, refractoriness °C, high temperature bending resistance Mpa. (3) Shape requirements: dimensional tolerances, missing corners and edges, cracks, distortions, melting holes, etc. (4) Packaging requirements: box-type packaging, bag-type moisture-proof packaging, and clear labels.

22. How many forms are there in technical standards for refractory products?

(1) National standard - formulated by the State Bureau of Technical Supervision, code-named "GB". (2) Industry standard - formulated by the former Ministry of Metallurgy, with the first code "YB". (3) Enterprise standards - formulated by the enterprise itself, and the first code is set by itself. (4) Agreement standard - receiving and supplying, negotiated and formulated by both parties.

23. What is the first step in the quality inspection of refractory products?

The first pass is to check the internal quality of refractory products, check the quality assurance certificate, and it should meet the requirements of the technical conditions in the supply contract, including:

(1) Chemical composition (inspection date, personnel, official seal of the inspection unit)

(2) Physical properties (inspection date, personnel, official seal of the inspection unit)

If there is any quality objection, samples can be sent to the Steel Research Institute and Refractory Company for re-examination.

24. What is the second level of quality inspection of refractory products?

The second pass is to check the appearance quality of refractory materials, which needs to be unpacked and unpacked for inspection, including: (1) dimensional tolerance; (2) missing edges and corners; (3) cracks; (4) distortion; (5) appearance color ; (6) melting hole; (7) particle size composition; (8) bonding performance.

Refractory products with substandard appearance should also be rejected, returned or replaced.

25. What is the third level of quality inspection of refractory products?

The third level is to check the packaging and quantity of refractory products, including:

(1) Packing box, packaging bag material quality, packaging quality; (2) Total weight (t) - car weight list, train weight list; (3) Quantity (block) - stack count; (package) - stack Inventory; (4) unit weight (kg) - over-weighing review;

Quantity, weight, and unit weight should be filled in according to the actual check, pay attention to deduct the weight of the packing box and bag, and avoid the economic loss of paying both the packing fee and the weight fee.

26. How to measure the dimensional tolerance of refractory products?

(1) According to the drawings and technical standards, align the zero point of the tape measure or steel ruler with the edge of the product. Read out the value at the end, and round off one digit after the decimal point.

(2) When measuring the inner and outer diameters of the products, use tool calipers to measure them.

27. What are the requirements for crack inspection?

(1) Use standard steel wires (0.1, 0.15, 0.25, 0.5mm) to insert into cracks naturally, and measure the width of cracks.

(2) Measure the length of the crack with a ruler.

(3) Check the number of cracks.

28. How to check the distortion?

Place the quilt inspection surface of the brick on the flat plate, use a feeler gauge (0.1, 0.2, 0.4, 0.5 mm) to insert into the largest crack along the board surface without force, and the insertion depth does not exceed 10 mm to be a qualified product.

Example: To check 2.0mm distortion, use a 2.1mm feeler gauge to insert a depth of no more than 10mm to be a qualified product.

29. What are the inspection requirements for missing corners and edges?

(1) Cubic goniometer is used for chipping, that is, the depth of chipping is the sum of three sides and should be less than the requirement of chipping depth.

Example: The depth of the missing corner is allowed to be ≤60mm, and the three sides of the missing corner a+b+e≤60mm are qualified products.

(2) The missing edge refers to the width along the direction of the angle between the two sides of the product, and the sum of the length of the missing edge should be less than the depth requirement of the missing edge.

Example: The depth of the missing edge is allowed to be ≤70mm, the width of the angle between the two sides of the missing edge is a+b, and the length of the missing edge is C, that is, a+b+c≤70mm is a qualified product.

30. What is a melting hole?

The melting cavities and significant discoloration parts on the surface of refractory products caused by low melting materials are called melting holes. Example: flow steel bricks for die casting have the following requirements for the diameter of the melting hole: the inner working surface ≤ 5mm, the outer non-working surface ≤ 8mm.

31. How to check and accept refractories?

Only when the quality and quantity of the refractory products meet the requirements for receiving materials can the supplier's delivery materials be signed for approval. At the end of the month, the workshop or the planning department will sign and write the receipt with the delivery slip, and then send it to the finance department for checkout, calculate monthly consumption, and calculate production costs.

32. What are the requirements for the storage of refractory materials?

(1) All refractory products should be placed in the factory building and should not be soaked by rain or water. Those with moisture-proof requirements should be placed in the baking kiln.

(2) When handling and laying bricks, they should be handled with care and arranged closely to avoid rolling and collision damage between bricks.

(3) Products of different types and brick numbers shall be stacked in piles with clear markings and the height shall not exceed 1.8m.

(4) For refractory products that require aging, they should be used within the validity period to prevent waste due to deterioration and failure.