Mechatronic Engineering Technology
OneCommonly used materials and equipment in mechanical and electrical engineering
(1) Fire-resistant cables
Fire-resistant cables refer to cables that can maintain safe operation for a certain period of time in the case of flame burning. It is divided into two categories: A and B, and Class A is when the flame temperature is 950 1000, it can continue to supply power for 90min; Class B is at a flame temperature of 750 800 meters, which can last for 90 minutes. Fire-resistant cables are widely used in high-rise buildings, subways, underground shopping malls, large power stations and important industrial and mining enterprises and other places related to fire safety and fire protection and life-saving.
(2) Magnesium oxide cable
Magnesium oxide cable is processed from copper core, copper sheath, and magnesium oxide insulating material. The material of magnesium oxide cable is inorganic, the melting point of copper and magnesium oxide is 1038 and 2800 respectively, the fire performance is excellent, and it also has the advantages of high temperature resistance (the cable allows long-term working temperature up to 250), explosion-proof, large current carrying capacity, good waterproof performance, high mechanical strength, long life, good grounding performance, etc. However, it is expensive, the process is complex, and the construction is difficult. In oil irrigation areas, important wood structure public buildings, high temperature places and other occasions with high fire resistance requirements, magnesium oxide cables can be used. Due to the particularity of the raw materials and processes of magnesium oxide cables, multi-core cables with a cross-section of more than 25mm2 are composed of single-core cables.
(3) Refractory motherTrunking
The fire-resistant busway shell is made of fireproof materials with high temperature resistance of not less than 1100, and the thermal insulation layer is made of insulating materials with high temperature resistance of not less than 300, and the fire-resistant time is 60min, 90min, 120min, 180min, and the full load operation can reach more than 8h. In addition to passing CCC certification, the fire-resistant busway should also have a type inspection report issued by a nationally recognized testing agency.
2. Professional technology in mechanical and electrical engineering
4) GTAW Welding:
The bottom layer of the weld of the following industrial pipes is welded using the GTAW (Tungsten Gas Shielded Welding) welding method:
Pipes with nominal diameter less than 600mm, design pressure greater than or equal to 10MPa or design temperature less than -20; Pipes that require high cleanliness inside and should not be cleaned after welding.
(5) Preheating and post-welding heat treatment
Heat treatment to improve the post-weld structure and properties of welded joints or to eliminate residual stresses.
1) Any wall thickness of 20hic requires pre-welding and post-welding heat treatment to prevent the occurrence of delayed cracks. If heat treatment cannot be carried out in time, it should be heated immediately after welding 200 350 heat preservation and slow cooling. The afterheating can reduce the influence of hydrogen in the weld, reduce the residual stress of welding, and avoid the martensitic structure of the welded joint, so as to prevent the generation of hydrogen-induced cracks.
2) When other grades of non-alloy steel are used in pressure vessels, the minimum preheating temperature is 15. When the thickness of the base metal of the welded joint of industrial pipes is 25mm, the minimum preheating temperature is 80. When the thickness of the base metal < 25mm, the minimum preheating temperature is 10.
(6) Measures to prevent the occurrence of delayed cracks
Welding rod drying, stress reduction, preheating before welding, and heat treatment after welding can be taken. Strictly implement the post-welding heat dehydrogenation treatment process, and polish the residual height of the weld. For steel that is prone to welding delay cracks, heat treatment should be carried out in time after welding. When heat treatment cannot be carried out in time, it should be evenly heated to 200 350 immediately after welding, and kept warm and cooled.
3. Construction technology of building mechanical and electrical engineering
7) Indoor domestic drainage pipes often use plastic pipes for building drainage, cast iron pipes for drainage of flexible interface mechanisms and corresponding pipe fittings; The ventilation pipe should be consistent with the drainage pipe; When the continuous drainage temperature is greater than 40, metal drainage pipe or heat-resistant plastic drainage pipe should be used; Pressure drainage pipes can be made of pressure-resistant plastic pipes, metal pipes or steel-plastic composite pipes.
8) The pipes of the building direct drinking water system should be thin-walled stainless steel pipes, copper pipes or other high-quality plastic pipes for water supply and high-quality steel-plastic composite pipes that meet the requirements of food grade. Metal pipes with a working temperature greater than 100 should be used for boiling water pipes.
9) During the construction of anti-corrosion projects, measures such as fire prevention, anti-freezing, and rainproof should be taken, and should not be operated in a humid or less than 5 environment, and corresponding environmental protection and labor protection measures should be taken.
(10) Energy-saving performance testing of ventilation and air-conditioning systems
The average indoor temperature in winter shall not be lower than the design temperature 2 and shall not be higher than 1, and the average indoor temperature in summer shall not be higher than the design temperature 2 and shall not be lower than 1.
Fourth, industrial mechanical and electrical engineering installation technology
(11) Rolling bearing assembly
When assembling by temperature difference method, the temperature of the bearing should be changed uniformly, the heating temperature of the bearing should not be higher than 120, and the cooling temperature should not be lower than -80.
The bearing temperature shall conform to the provisions of the product technical documents or design documents; If there is no regulation, the temperature rise of the rolling bearing shall not exceed 40, its maximum temperature shall not exceed 80, the temperature rise of the sliding bearing shall not exceed 35, and its maximum temperature shall not exceed 70.
Lubrication, sealing, hydraulic, pneumatic (steam) power, cooling and other auxiliary systems work normally, no leakage, and the maximum temperature of the fuel tank shall not exceed 60.
(14) Trial operation of axial flow fan.
Generally, the temperature measured by the axial flow fan on the bearing surface shall not be higher than the ambient temperature 40; The normal working temperature of the rolling bearing should not exceed 70, the instantaneous maximum temperature should not exceed 95, and the temperature rise should not exceed 60; The normal operating temperature of the plain bearing should not exceed 75 °C. The safety and interlocking alarm and shutdown control system of the fan should be simulated and tested, and its action should be sensitive, correct and reliable, and the measured value should be recorded for future reference.
pumps: The temperature rise of the lubricating oil of the bearing, bearing housing and sump should not exceed the ambient temperature of 40. The temperature of the plain bearing should not be greater than 70, and the temperature of the rolling bearing should not be greater than 80.
(16) ValveThe shell test pressure is 15 times, the seal test is 1. of the maximum allowable working pressure of the valve at 201 times, the test duration shall not be less than 5min, when there are no special provisions, the test temperature is 5 40, when it is lower than 5, temperature raising measures should be taken.
(17) Oil cleaningIt should be done in a circular manner. The oil temperature should be raised and lowered repeatedly within 40 70 times every 8 hours, and the filter element should be cleaned or replaced in time.
For transformers transporting dry gas, the gas pressure inside the tank should be kept at 001～0.03MPa, dry gas** must be below -40, always maintain positive pressure, and set a pressure gauge for monitoring.
(19) Precautions when the motor is drying:
Before drying, the drying method and related technical measures should be formulated according to the moisture condition of the motor.
The drying temperature rises slowly, and the temperature rise per hour is generally controlled at 5 8
The temperature should be strictly controlled in drying, within the specified range, the maximum allowable temperature of drying should be determined according to the grade of the insulating material, and the maximum temperature of the general core and winding should be controlled at 70 80
20) Construction requirements for automation instrument lines: heat insulation measures should be taken when the ambient temperature around the line exceeds 65; Fire prevention measures should be taken when there is a fire source nearby.
21) The ambient temperature requirement is not less than 0 when laying plastic insulated cables, and the ambient temperature requirements are not less than -15 when laying rubber insulated cables
(22) Instrument pipeline test
Clean water should be used for the hydrostatic test medium, and the chloride ion content in the water should not exceed 25mg l when the test is carried out on austenitic stainless steel pipes. When the test is carried out below the ambient temperature of 5, anti-freezing measures should be taken.
(23) General requirements for automatic instrument commissioning:
Before installation, the instrument should be inspected, calibrated and tested. Calibration and testing prior to instrument installation should be carried out indoors. There is no electromagnetic field interference in the laboratory; The room temperature is kept at 10 to 35.
The power supply voltage of the instrument test should be stable. The voltage fluctuation range of AC power supply and DC power supply above 60V should be less than 10%, and the voltage fluctuation range of DC power supply should be 5%.
The air source of the instrument test should be clean, dry, and the pressure should be stable, ** more than 10 times lower than the minimum ambient temperature.
24) Open dry jetting is to use compressed air to remove rust by spraying clean and dry abrasives, the compressed air used should be oil-free and dry, and the temperature of the metal surface should be higher than **3.
(25) The basic requirements of anti-corrosion construction
The construction environment temperature should be 10 30, the relative humidity should not be greater than 85 or the surface temperature of the coated substrate should be higher than the ** temperature 3.
(26) Expansion joint retention width requirements
When the design temperature is equal to or greater than 350, the width of the expansion joint should be 25mm; When the design temperature is less than 350, the width of the expansion joint should be 20mm.
When the insulation layer is double-layer or multi-layer, expansion joints should be left for each layer, and should be staggered, and the staggered spacing should not be less than 100mm.
(27) Hydrostatic test:The test medium should be clean fresh water. When the austenitic stainless steel tower is used as the pressure test medium, the chloride ion content in the water shall not exceed 25ppm, and the water temperature of the hydrostatic test shall not be less than 5.
(28) Storage tank test:Clean fresh water is used for the water filling test, the test water temperature is not less than 5, and for stainless steel tanks, the chloride ion content in the test water shall not exceed 25ppm; Foundation settlement observation should be carried out in the water filling test.
(29) Steel structure production
Cutting & Processing:
For mechanically sheared parts, the thickness of the steel plate should not be greater than 120mm, the shear surface should be flat, carbon structural steel should not be sheared and punched when the ambient temperature is lower than -20, and low-alloy steel is lower than -15.
Deformation correction:
When the section steel is heated and corrected, the heating temperature is selected according to the steel performance, and the carbon structural steel should not be cold corrected and cold bent when the ambient temperature is lower than -16 and the low alloy structural steel is lower than -12.
When carbon structural steel and low-alloy structural steel are heated and corrected, the heating temperature should be 700 800, the maximum temperature is strictly forbidden to exceed 900, and the minimum temperature shall not be less than 600; Low-alloy structural steels should be naturally cooled after heat correction.
(30) Trial operation of rolling mill equipment
The temperature of the bearing of the test run equipment should be normal, the temperature rise of the rolling bearing should not exceed 40, and the maximum temperature should not exceed 80; The temperature rise of the plain bearing bearing shall not exceed 35, and the maximum temperature shall not exceed 70.
(31) Technical requirements for winter construction
Masonry should be carried out in a heated environment. The temperature of the working place and the surrounding masonry should not be lower than 5, and the refractory bricks and prefabricated blocks should be preheated to more than 0 before masonry.
The mixing of refractory mud and refractory castable should be carried out in the greenhouse. Refractory mud, refractory plastic, refractory spray paint and cement refractory castable should not be lower than 5 during construction. However, the temperature of clay combined with refractory castables, water glass refractory castables, and phosphate refractory castables should not be lower than 10.
The water of the refractory castable can be heated, and the heating temperature is: the water temperature of the Portland cement refractory castable should not exceed 60; The water temperature of the refractory castables of high-alumina cement should not exceed 30. Cement must not be heated directly. During the construction of refractory castables, no additional coagulant promoter shall be added.
(32) Curing of refractory castable for winter construction:
Cement refractory castables can be cured by heat storage method and heating method. The temperature of heating Portland cement refractory castable shall not exceed 80; The temperature of heating high-alumina cement refractory castable shall not exceed 30.
The curing of clay, water silicate and phosphate cement castable should be done by dry heat method. The temperature of the water glass refractory castable shall not exceed 60.
Mechanical and electrical engineering related regulations and standards
33) The material of water pipes and fittings should be corrosion-resistant, and should have the ability to withstand a drainage temperature of not less than 40 and continuous drainage. The interface installation connection should be reliable and safe.
34) The smoke exhaust fan can be an ordinary centrifugal fan or a smoke exhaust axial fan; The smoke exhaust fan and its inlet and outlet soft joints should be able to work continuously for 30min when the flue gas temperature is 280. Smoke exhaust fans must be made of non-combustible materials. The main pipe at the entrance of the smoke exhaust fan should be provided with a smoke exhaust fire damper that can be automatically closed when the flue gas temperature exceeds 280, and the valve should be interlocked with the smoke exhaust fan, and when the valve is closed, the smoke exhaust fan should be able to stop running.
35) When the high-strength bolt connection is heated for a long time of more than 150, heat insulation protection measures such as heat-resistant and heat-resistant insulation coating and thermal radiation shielding should be adopted.
M&E project management matters
(36) Compressor commissioning
During the no-load test operation, the crank device should be checked in the position required for the compressor start-up; After checking that there is no abnormal phenomenon in each part, the inching compressor shall run for 5min, 30min and 2h in turn, and the lubricating oil pressure shall not be less than 01MPa, the temperature of the crankcase or lubricating oil in the fuselage should not be higher than 70, there is no abnormal sound in the moving parts, and there is no loosening of the fasteners.
No-load test operation, the procedure, pressure and operation time of the booster operation should be in accordance with the provisions of the random technical documents, the document is not specified, and the exhaust pressure should be 1 4 hours of continuous operation when the rated pressure is 1 4; When the exhaust pressure is 1 2 and 3 4 of the rated pressure, it should run continuously for 2 hours; The continuous operation under the rated pressure should not be less than 3h. In the process of step-up operation, the pressure should be gradually increased after there is no abnormal phenomenon in the operation under the previous level of pressure. During operation, the lubricating oil pressure shall not be lower than 01MPa, the temperature of the crankcase or lubricating oil in the fuselage should not be higher than 70, of which the oxygen compressor should not be higher than 60.
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