Is there a national standard for intermediate frequency furnace and electroslag furnace steelmaking?

Technical specification for safety of intermediate frequency furnace in metal smelting enterprises

1 range

This document specifies the terms and definitions, basic requirements, safety devices, prenatal inspection, charging and operation, furnace building and drying, and emergency management of intermediate frequency induction furnaces.

This document is applicable to the use of medium frequency furnaces in metal smelting enterprises in metallurgy, nonferrous metals and machinery industries. Other industries that use intermediate frequency furnaces and power frequency furnaces can refer to the implementation.

2 normative reference documents

The contents in the following documents constitute the indispensable clauses of this document through the standards cited in the text. Among them, there is a dated reference file, and only the version corresponding to this date is applicable to this file; For undated reference documents, the latest version (including all revisions) is applicable to this document.

GB/T 10067. 1 Basic technical conditions for electrothermal and electromagnetic processing devices Part 1: General.

GB50034 design standard for building lighting

GB 50 140 Code for Design of Fire Extinguishers in Buildings

AQ 200 1 safety regulations for steelmaking

AQ/T 9007 "Basic Specification for Emergency Drill of Production Safety Accidents"

3 Terms and definitions

The following terms and definitions apply to this document.

3. 1 medium frequency induction furnace

The working frequency is in the range of 60 Hz ~ 10 kHz, and the industrial furnace melts metal by electromagnetic induction principle.

3.2 Induction coil

A device in which a copper tube is wound into a spiral shape according to a certain number of turns, and an induction magnetic field is generated by alternating current to heat the metal.

3.3 yoke yoke

The device is made of silicon steel sheets stacked up and down, which limits the magnetic leakage of the induction coil and improves the induction heating efficiency.

3.4 Intermediate Frequency Furnace Operator

Personnel engaged in the operation, charging, furnace building, oven drying, inspection and maintenance of intermediate frequency furnaces, including the team leader of the above positions.

3.5 Hazardous operation areas in hazardous operation areas

Areas that may be affected by high-temperature molten metal splashing, such as the periphery of intermediate frequency furnace, molten metal crane conveying line, casting area, etc.

3.6 Operation pit

The storage pit, die casting pit and sand casting pit in front of intermediate frequency furnace are collectively called operation pit.

3.7 Moisture condensation

When the surface temperature of an object is lower than the dew point temperature of nearby air, condensed water will appear on the surface.

4 Basic requirements

4. 1 management requirements

4. 1. 1 The safety facilities of the newly-built, rebuilt and expanded middle shield furnace project must be designed, constructed and put into production and use at the same time as the main project.

4. 1.2 The enterprise shall formulate the management system for the use of intermediate frequency furnaces, and refer to the instructions for the use of equipment and refractories, and formulate the systems and regulations such as daily inspection and maintenance standards, furnace building and drying standards, crucible or lining scrapping standards, post operation reports (safety operation procedures), and emergency plans for production safety accidents.

4. 1.3 Enterprises should improve the responsibility system for safety production of the merged safety personnel, and establish a double prevention mechanism of classified management and control of safety risks and investigation and management of hidden dangers. Advanced technical means should be used to reduce security risks. The enterprise shall complete the periodic report of major security risks in the first year of each year. The enterprise shall organize a special safety inspection covering all intermediate frequency furnaces at least once every quarter, truthfully record the hidden dangers of accidents and rectification found in the inspection, and inform employees.

4. 1.4 The waste iron and steel raw materials used in the intermediate frequency furnace shall be radioactive tested or provided with the radioactive test certificate of the supplier.

4. 1.5 When the intermediate frequency furnace is overhauled, the power shaft of the intermediate frequency furnace must be locked and listed. The operation can only be started after taking technical measures such as electricity inspection and discharge, and the copper bar connected with the induction coil should be grounded during the operation.

4.2 Personnel requirements

4.2. 1 The enterprise shall set up a safety production management organization or be equipped with full-time safety production management personnel, who shall be familiar with the safety characteristics of intermediate frequency furnaces and master relevant safety skills. The number of full-time safety production management personnel shall conform to the provisions of the Regulations of Jiangsu Province on Safety Production, and the management personnel mainly responsible for safety production in enterprises shall receive training and assessment, and obtain the qualification certificate of safety production knowledge and management ability assessment in metal smelting enterprises.

4.2.2 Intermediate frequency furnace operators must be trained and qualified before they can work at their posts.

4.2.3 Operators within the influence range of magnetic field shall not wear metal bracelets, bracelets, necklaces, magnetizable articles or articles such as silicon and carbon, and personnel with metal implants shall not engage in corresponding operations.

4.3 Equipment and facilities requirements

4.3. 1 an aluminum shell intermediate frequency furnace with a capacity of 0. 25t or larger without yoke shall not be used.

4.3.2 The induction coil of intermediate frequency furnace and its turn-to-turn shall be fixed and positioned with solid structural support (bakelite column) bolts, nuts and pull rods.

4.3.3 The magnetic yoke shall be made of silicon steel sheet, and its cross-sectional area and length shall be able to limit magnetic leakage and support the load of induction coil. The yoke of the intermediate frequency furnace should be evenly distributed on the outer surface of the induction coil and fastened with the furnace body into a whole, and the ejector rod of the yoke top block should be complete without looseness.

4.3.4 If the capacitor cabinet, power supply device and furnace body of the intermediate frequency furnace are arranged on the same floor, a partition wall shall be set between them, and the hole where the power supply pipeline passes through the wall and floor shall be blocked (except for the integral furnace base or furnace body, and the furnace base with open capacitor and control cabinet).

4.3.5 For building components that may be affected by molten metal splashing, such as melting zone, molten metal conveying line, pouring zone, etc., heat insulation protection measures should be taken.

4.3.6 There should be no water seepage in the operation pit set in front of the intermediate frequency furnace. If the groundwater level is high, waterproof measures should be taken. The volume of the operation pit with emergency storage function shall meet the maximum volume requirement of the intermediate frequency furnace or molten metal transfer ladle.

4.4 Site Environmental Requirements

4.4. 1 It is forbidden to set up meeting rooms, shift rooms, activity rooms, lounges, dressing rooms and other crowded places in and around dangerous operation areas such as melting zone, molten metal lifting zone and casting zone; There should be no warehouses and storerooms for flammable and combustible materials around; The exit (including windows) of the independent operation room should not face the furnace mouth, and the emergency escape door should be set away from the melting zone.

4.4.2 It is forbidden to install water pipes, gas pipes, fuel pipes, hydraulic oil pipes, wires and cables on the ground below the intermediate frequency furnace and in the operation pit. If it is unavoidable, reliable protection measures should be taken.

4.4.3 There shall be no accumulated water within the influence range of molten metal leakage and splash, and inflammable and explosive articles shall not be placed.

4.4.4 Harmful gas and combustible gas pipelines should not be laid in operation pits and basements.

4.4.5 The ground elevation of the workshop in the smelting area should be more than 0.3m higher than that around the plant area, and measures should be taken to prevent the roof from leaking rain and the skylight from leaking rain, and there should be no water on the ground in the area.

4.4.6 The working face of the furnace shall be smooth and the materials shall be neatly stacked. At least two emergency passages meeting the escape requirements should be set at both ends or at the rear of the furnace, and they should be kept unblocked. A guardrail with a height of not less than 1. 05m should be set around the furnace.

4.4.7 The affected areas such as molten metal leakage, splashing or fire under the furnace should be closed for management, and the spaces under multiple furnace seats should be arranged through. When any intermediate frequency furnace in the area is smelting, the whole area is forbidden to enter.

4.4.8 The metal smelting workshop shall be provided with safe passages, and the passages shall be kept unblocked.

4.4.9 If the intermediate frequency furnace is empty, measures should be taken to prevent people from falling into the furnace mouth.

5 safety device

5. 1 The cooling water of induction coil of intermediate frequency furnace shall be equipped with detection and alarm devices for inlet pressure, inlet and outlet flow difference and outlet temperature of each loop. The detection and alarm signals of inlet pressure and outlet temperature of each loop should be interlocked independently, and the intermediate frequency power supply should be cut off. The detection history data should be visible, the alarm signal should be installed in the position where the operator can easily observe and process it, and the detection alarm system should be equipped with uninterrupted power supply.

5.2 The air inlet pipe of induction coil of intermediate frequency furnace should be equipped with automatic or manual control quick cut-off valve, and the installation point of control facilities should be on the furnace which is convenient for operators to handle quickly.

5.3 Enterprises should be equipped with emergency standby boiler cold water source, which can be automatically switched when the normal cooling water supply is interrupted.

5.4 All accessible parts of intermediate frequency furnace feed shall have isolation and protection measures such as net cover. Furnace frame, capacitor cabinet, intermediate frequency power supply device, console shell, etc. Should be reliable grounding, grounding resistance is not greater than 4ω.

5.5 If the intermediate frequency furnace is 1t or above, a lining leakage alarm device shall be installed. When the leakage current monitoring reaches the alarm value, an alarm signal should be sent out and the intermediate frequency power supply should be cut off by interlocking.

5.6 Intermediate frequency furnace shall have the functions of tilting limit and emergency tilting.

Prenatal check-up of 6 students

6. 1 operating conditions

6. 1. 1 The operating pit in front of the furnace and the bottom of the furnace body should be kept dry, and there should be no accumulated water and inflammable and dazzling articles.

6. 1.2 The working lighting in the melting, casting and molten metal lifting areas shall meet the operation requirements, and emergency lighting shall be provided.

6. 1.3 The observation window of the melting chamber of the vacuum induction melting furnace should be intact, and the observation of the whole process of melting and casting can be ensured.

6.2 furnace body

6.2. 1 Before operation, check whether there are serious cracks, spalling of refractory materials and serious erosion on the inner surface of furnace lining.

6.2.2 Check whether the turnover mechanism of the furnace body and the moving mechanism of the furnace cover are working normally.

6.2.3 Check the cable for cracks, scratches and wear.

6.2.4 Check whether the stressed frame is deformed.

6.2.5 If the intermediate frequency furnace is under any of the following circumstances, it shall not be used again without repair.

A) The lining of intermediate frequency furnace is seriously eroded, and the weakest part is less than 40% of the new lining thickness.

B) The valves, cylinders, pipes and tubing joints of the intermediate frequency furnace hydraulic system are loose, leaking oil and damaged.

C) Leakage of valves, pipes and joints of cooling water pipes.

D) The induction coil mastic peels off, exposing knotted materials.

E) The bakelite column of the induction coil is broken, and the fixing bolts and nuts are missing.

F) The ejector pin of the yoke top block is missing or loose.

G) The detection and alarm devices such as inlet water pressure, inlet and outlet water flow difference and outlet water temperature of each circuit are invalid, and the interlocking functions of water pressure, backwater temperature and power supply of capacitor cabinet are invalid.

H) furnace leakage alarm device failure.

6.3 Safety accessories

6.3. 1 Furnace leakage monitoring and alarm device shall be reliable and effective.

6.3.2 Detection and alarm devices for water flow difference, outlet water temperature and inlet water pressure of the furnace body shall be in good condition.

6.3.3 The facilities for quickly cutting off the inlet pipe of induction coil of intermediate frequency furnace shall be intact, flexible and effective.

6.3.4 The emergency water supply system of diesel engine should check the starting power supply, oil quantity and water output of diesel generator every week.

6.3.5 As an emergency water supply measure, the high-level water tank should store at least 15 minutes of cooling water during normal production, and keep the water quality in the tank clean.

6.3.6 Power cabinet cooling water pressure detection and power-off interlock shall be in good condition.

6.4 Others

6.4. 1 The connection points of furnace changing switch and copper bar shall be inspected regularly, and there shall be no looseness and carbon deposition during arc drawing.

6.4.2 Check the intermediate frequency furnace transformer. The oil quantity should be normal, and there is no abnormal sound during the power-on test.

6.4.3 Isolation and protection measures for accessible parts of all feed parts of intermediate frequency furnace shall be good.

6.4.4 The electric control cabinet should be kept clean and tidy. No sundries, abnormal sound or peculiar smell: the instrument and display screen of the operation desk are normal.

6.4.5 Metal dust on the coil and yoke surface of vacuum induction melting furnace should be cleaned regularly to avoid affecting the insulation performance of the coil and causing arc.

6.4.6 The cooling water quality of induction coil of intermediate frequency furnace shall meet the requirements of GB/T 10067+0.

6.5 inspection records

The enterprise shall establish inspection records, the contents of which shall include the relevant contents of 6. 1, 6.2, 6.3 and 6.4 of this standard.

7 burden and operation

7. 1 charging requirements

7. 1. 1 metal materials, alloys, auxiliary materials, etc. The furnace shall not be wet and greasy, shall not be equipped with closed or semi-closed containers, and shall not be equipped with ammunition, radioactive substances, explosives and scrap metal materials that will damage the furnace lining.

7. 1.2 The size of waste steel charged into the furnace should be less than 1/2 of the diameter of the furnace mouth, and the phenomenon of bridging steel above the molten pool should be avoided.

7. 1.3 Suitable tools should be used for melting and feeding, and the feeding speed should be uniform to avoid impact damage to the furnace lining or splashing of molten metal.

7. 1.4 The vacuum induction melting furnace should not use metal materials with excessive slag, and the total amount added to each furnace should ensure the free space required for vacuum degassing.

7.2 Operating requirements

7. 2. 1- In any of the following circumstances, stop the furnace immediately:

A) Whether there is any alarm signal of electric leakage or furnace leakage when the intermediate frequency furnace is working;

B) If the water pressure and water temperature of the intermediate frequency furnace electric cabinet have abnormal signals;

C) There are abnormal signals in water pressure, water temperature and flow rate of intermediate frequency furnace body;

D) The temperature of molten metal exceeds the process allowable temperature of refractory materials.

7.2.2 If dual power supply is adopted as an emergency measure, it should have automatic switching function, the standby pump should have automatic switching function, and the operating platform should be equipped with start-up display signal.

7.2.3 When metal tools are used for sampling, temperature measurement and slag scraping, etc. During smelting operation, the power supply of the intermediate frequency furnace should be cut off, and the standing part of the operator should be paved with insulating materials or wear insulating shoes.

7.2.4 In the process of melting and charging, personnel should wear protective articles, including protective articles to prevent scalding of high-temperature melt.

7.2.5 When the vacuum degree of vacuum induction melting furnace rebounds after reaching the limit pressure, stop the furnace to confirm whether there is water leakage.

8 furnace building and drying

8. 1 Furnace preparation

8. 1. 1 Personnel involved in building a furnace and tying knots are not allowed to carry metal objects with them.

8. 1.2 Between the furnace lining and the induction coil, there should be an insulating layer of H-class or above insulating material and an insulating layer of insulating material with working temperature not lower than 500℃ ... When the whole lining is required to be pushed out, a loose lining should be set. It is forbidden to use materials containing asbestos.

8. 1.3 Dry ramming materials should be stored in a dry place, and iron filings, iron oxide and other metals should be avoided during storage. Check the dryness before use, and the storage time shall not exceed 12 months.

8.2 furnace building requirements

8.2. 1 The lining thickness of the intermediate frequency furnace should reach the design size, and the tamping, baking and sintering of the lining should be carried out in strict accordance with the process provided by the refractory manufacturer.

8.2.2 When laying the furnace bottom with refractory fiber products, it should be laid flat and even in thickness, and there should be no gap at the edge of the furnace bottom.

8.2.3 If unshaped refractory materials are used to ram the furnace lining, the furnace bottom should be dried and cleaned before ramming the furnace bottom. Ramming materials should be spread evenly. When compacted by power hammer, the paving thickness of each layer shall not exceed 100mm, and it shall be rammed for half a hammer and compacted continuously and evenly step by step. The second paving shall be carried out after the tamping material junction is leveled. The working wind pressure in power hammer should not be less than 0. 5 MPa.

8.2.4 Precast crucibles should be used, and the upper and lower openings of the mold should be evenly placed, and necessary fixing measures should be taken. The furnace wall outside the crucible should be knotted layer by layer.

8.2.5 After knotting, the furnace body should not be tilted before baking and should not hit the crucible mold.

8.3 oven requirements

8.3. 1 When using scrap iron and steel to bake, small pieces with the length and width not exceeding 1/3 of the furnace mouth size should be selected, and the feeding speed should be ensured not to damage the furnace lining, and the baking should be carried out according to the heating curve of the intermediate frequency furnace baking process.

8.3.2 When baking a new furnace lining with molten metal injection, the furnace lining should be preheated before injection, and the preheating curve should meet the technical requirements of refractory materials.

8.3.3 Pay attention to the water temperature of the induction coil during oven drying, and check the dew condensation on the outer surface of the induction coil to avoid coil turn-to-turn discharge.

9 emergency management

9. 1 emergency facilities

9. 1. 1 The enterprise shall allocate fire-fighting facilities as required, including but not limited to:

A) The configuration of fire extinguishers in the kiln workshop shall meet the relevant requirements of GB 50 140.

B) Each medium frequency furnace shall be equipped with not less than 2m fire extinguishing sand and not less than 2 fire shovels. Fire extinguishing sand should be kept dry, and the fire extinguishing sandbox should have measures to prevent rain soaking.

C) Fire extinguishers and fire sandbox should be placed near doors or key protective equipment.

9. 1.2 The design of the area under the furnace should meet the requirement that molten metal can quickly flow into the operating pit in front of the furnace in case of furnace leakage accident. There shall be no moisture and water in the area under the furnace and the operation pit in front of the furnace. Necessary emergency storage facilities should be set up along the high-temperature molten metal conveying line and casting area.

9. 1.3 Workplace lighting (obstacle lighting, emergency lighting, including standby lighting, safety lighting and evacuation lighting, etc. ) and the minimum illumination in the workplace shall comply with the provisions of GB50034.

9.2 Emergency Plan and Exercise

9.2. 1 should be based on the number and tonnage of intermediate frequency protection in the enterprise. Considering the actual security risks comprehensively. Carry out safety risk assessment and emergency resource investigation, and establish an emergency plan system for production safety accidents. The emergency plan should at least include emergency treatment such as power failure, water cut-off and furnace leakage of the shield furnace.

9.2.2 Enterprises shall organize companies, workshops and teams to carry out emergency drills for production safety accidents in accordance with AQ/T 9007. The content of the drill includes power failure, water cut and furnace leakage of the intermediate frequency furnace.

9.2.3 Enterprises should draw lessons from the production safety accidents of intermediate frequency furnaces in a timely manner, and revise the emergency plan for production safety in a timely manner in combination with the actual situation of enterprises.