Common sense of welder's use

1. Basic knowledge of welding operation

Welders must undergo special technical training and practical operation, and can only work at their posts after passing the examination and obtaining the operation certificate.

2. Welders should wear canvas overalls and working caps. Don't stick your coat in your pants, cover your pockets and have shoe covers on your feet.

3. The shell and workbench of fixed or mobile electric welding machine must be well grounded, and the power supply should be disassembled by an electrician. Place it stably to avoid vibration and collision. Place should be well ventilated, dry and rainproof.

4. The * * * conductive part and rotating part of the electric welding machine and the cooling fan shall be equipped with protective covers. The electric welding machine must be equipped with a leakage protector, and the rated leakage action should be less than 0.1s.

5. The welder should be cleaned frequently and kept clean. In places with corrosive gases and conductive dust, isolation and maintenance must be carried out.

Six. The electric welding machine shall be equipped with a separate switch, which shall be placed in a rain-proof switch box, and gloves shall be worn when it is closed, and it shall be operated sideways.

7. Before closing, the welder should check the welding equipment. The bushing is well grounded, and there is no insulation damage, short circuit or poor contact on the lead.

Eight. The electrode holder must be able to firmly clamp covered electrode, covered electrode has good contact with the electrode holder, and the grip is well insulated.

Nine. Steel wire and grounding wire are strictly forbidden to contact with steel wire rope. Wires must use flexible wires with good insulation. If there is a joint, it must be firmly connected and well insulated. It is forbidden to use metal structures, pipes, tracks, steel wires or other metals in the workshop to lap instead of the zero line.

10. Wear welding gloves and insulating shoes when welding. When working in a wet place, you should stand on an insulating board or a dry board. When your body is sweating and your clothes are wet, you shouldn't lean against charged steel plates and other weldments.

1 1. When replacing covered electrode, you must wear welding gloves and do not operate with your bare hands. When charging, do not clamp the electrode holder under your arm to move the weldment or hang the welding cable around your neck.

12. Welding on the pressure vessel road is prohibited. Welding live equipment must first cut off the power supply.

13. When welding in a closed metal container, the container must be grounded and well ventilated, and two people should take turns to monitor or weld. It is forbidden to input oxygen into the container. 12V safety line lamp shall be used for lighting.

Fourteen. When welding containers or pipelines that store flammable, explosive and toxic substances, they must be cleaned and all orifices must be opened.

15. When welding the preheated workpiece, insulation measures such as asbestos cloth or baffle should be taken.

16. When replacing the mobile handle on site, cut off the power supply and don't climb the ladder with the handle.

17. When several welding machines are welded together, a light shield shall be provided.

18. In the process of lifting parts, it is forbidden to weld while lifting, and welding can only be carried out after removing the wire rope.

19. Remove welding slag. Wear protective glasses or masks when cleaning the roots with arc gouging to prevent iron slag from splashing and hurting people.

Thorium and tungsten should be put in a sealed iron box. Gloves and masks must be worn when grinding thorium and tungsten electrodes, and dust must be removed in time.

2 1. The shell of the carbon dioxide gas preheater should be insulated, and the terminal voltage should not be greater than 36V.

Twenty-two Professional welding torch cable must be used for TIG welding. Pay attention to prevent ultraviolet rays and high frequency from harming human body when welding.

Twenty-three During the thunderstorm, the open-air welding operation should be stopped.

Twenty-four Inflammable and explosive materials around the welding site should be removed, or covered and isolated. When welding must be carried out in the diffusion area of flammable and explosive gas or liquid, it should be approved by the relevant departments before welding.

Twenty-five After the work, cut off the power supply of the welding machine, check the operation site and confirm that there is no fire danger before leaving.

2. Common sense and methods of welder's safety operation procedures

The welder's common sense and methods are safe, and the operating procedures are as follows:

1, should master the general electrical knowledge, observe the general safety regulations of welders, and be familiar with fire extinguishing technology, electric shock first aid and artificial respiration methods.

2. Check whether the power cord, lead-out wire and connection point of the electric welding machine are in good condition before work, and the line crossing the roadway should be overhead or covered with protective cover; The secondary circuit and shell of welding machine must be well grounded; The covered electrode clip must be well insulated.

3. Open-air welding is not allowed in rainy days. When working in wet areas, you should stand where insulating articles are placed and wear insulating shoes.

4, mobile welding machine from the power grid wiring or inspection, grounding work must be carried out by an electrician.

5. When pushing the knife switch, the body should be skewed, and the feet should be pushed at one time, and then the welding machine should be turned on; The welding machine must be turned off first, and then the power switch can be unplugged.

6, mobile welding machine position, must first stop the power supply; If welding stops suddenly, please turn off the welding machine immediately.

7. When welding in crowded places, a fence should be installed to block the arc light. When there is no fence, remind people around you not to look directly at the arc light.

8. Wear gloves when replacing covered electrode, and don't lean on iron plates or other conductive objects. Wear protective glasses when tapping slag.

9, when welding non-ferrous metal equipment, should strengthen ventilation detoxification, use filter gas mask when necessary.

10. In case of gas leakage, when repairing the gas pipeline or welding, you must inform the gas station and the fire and safety department in advance and get permission before you can start working. Before work, the gas source must be turned off and ventilation should be strengthened to eliminate the blown gas.

1 1. Turn off the welding machine after work, and then disconnect the power supply.

3. The use of welding and matters needing attention

Original publisher: Zhao Qingqing.

The quality requirements of solder joint and inspection should include three aspects: good electrical contact, firm mechanical combination and beautiful appearance. The most important thing to ensure the quality of solder joints is to avoid virtual welding. 1. The reason and harm of virtual welding is mainly due to the oxide and dirt on the surface of the welded metal, which makes the solder joint in a connection state with contact resistance, which leads to abnormal circuit work, unstable connection between good and bad, and irregular noise increase, which brings great hidden dangers to the debugging, use and maintenance of the circuit. In addition, some virtual solder joints keep good contact for a long time after the circuit starts to work and are not easy to be found. However, under the action of environmental conditions such as temperature, humidity and vibration, the contact surface gradually oxidizes and the contact gradually becomes incomplete. The contact resistance of virtual solder joint will cause local heating, and the increase of local temperature will further worsen the incomplete contact of solder joint, and finally even make the solder joint fall off, and the circuit will not work normally at all. This process can last for a year or two, and its principle can be explained by the concept of "primary battery": when the solder joint is wet, water molecules dissolve metal oxides and dirt to form electrolyte, and the copper and lead-tin solders on both sides of the virtual solder joint are equivalent to the two electrodes of the primary battery. Lead-tin solder loses electrons and is oxidized, while copper material gains electrons and is reduced. In such a galvanic cell structure, metal corrosion occurs at the virtual solder joint, local temperature rise intensifies the chemical reaction, and mechanical vibration makes the gap between them expand continuously until a vicious circle finally forms an open circuit at the virtual solder joint. According to statistics, nearly half of the failures of electronic products are caused by poor welding. However, it is not easy to find out the virtual solder joint that causes the fault from the electronic devices with thousands of solder joints. Therefore, virtual welding is a hidden danger of circuit reliability.

4. The use of welding and matters needing attention

Safety precautions and preventive methods of electric welding. Electric welding, also called arc welding, is a technological method that the cross section of the welded metal is locally heated and melted to a liquid state by the arc thermal effect generated by welding equipment, so that the originally separated metals are combined into a solid and inseparable joint.

According to different welding processes, arc welding can be divided into automatic welding, semi-automatic welding and manual welding. Automatic welding and semi-automatic welding are mainly used in the manufacture of large-scale mechanical equipment, most of which are installed in factories with relatively fixed workplaces; Manual welding has good flexibility because it is not limited by workplace conditions. At present, it is widely used in open-air construction.

Because the workplaces are very different, electricity, light, heat and open flames will be generated during work, so there are various hazards in welding operations. A, easy to cause electric shock accident 1, in the process of welding, because the welder should often change the covered electrode and adjust the welding current, the operation should directly contact the covered electrode and the electrode plate, and the welding power supply is generally 220 V/380 V When the electrical safety protection device fails, the labor protection articles are unqualified, and the operators operate illegally, electric shock accidents may be caused.

If welding is carried out in metal containers, pipelines or wet places, the risk of electric shock is greater. 2. When the welder is unloaded, the voltage of the secondary winding is generally 60~90V, which is easily overlooked by the welder because of its low voltage, but its voltage exceeds 36V in safe voltage, which is still dangerous.

Assuming that the no-load voltage of the electric welding machine is 70V, people work in a high temperature and humid environment. At this time, the human body resistance R is about1600Ω. If the welder's hand touches the lower jaw, the current I passing through the human body is: I=V/R=70/ 1600=44Ma. Under the action of this current, the welder's hand will spasm, which is easy to cause electric shock accidents. 3. Because the welding operation is mostly carried out in the open air, the welding machine, the welding handle wire and the power cord are mostly in high temperature, high humidity (construction site) and dust environment, and the cooker is often overloaded, which is easy to make the insulation of the power cord and the electrical circuit aging, and the insulation performance is reduced, which is easy to lead to leakage accidents.

Second, it is easy to cause fire and explosion accidents. Because there is arc or open flame during welding, it is easy to cause fire when working in places with flammable materials. Especially in flammable and explosive device areas (including pits, ditches, grooves, etc.). ), it is more dangerous to weld containers, towers, tanks and pipelines that have stored flammable and explosive media.

Third, it is easy to cause burns. Arc and metal slag will be produced during welding. If the welder does not wear special protective work clothes, gloves and leather shoes for welding, especially when welding at high places, welding sparks will splash out. If protective isolation measures are not taken, it is easy to cause skin burns to the welder himself or the construction personnel below the working face. Fourth, it is easy to cause electro-optic ophthalmia. Due to the strong visible light and a large number of invisible ultraviolet rays generated during welding, it has a strong harmful effect on people's eyes. Long-term direct exposure can cause eye pain, photophobia, tears and fear of wind. , it will easily lead to inflammation of conjunctiva and cornea (commonly known as electro-optic ophthalmia).

Verb (abbreviation of verb) The arc produced by welding with light radiation function contains infrared rays, ultraviolet rays and visible light, which has radiation effect on human body. Infrared ray has the function of heat radiation, and welding in high temperature environment can easily lead to heatstroke of workers; Ultraviolet rays have photochemical effects and are harmful to human skin. At the same time, long-term exposure to the outside skin will also make the skin desquamate, and long-term exposure to visible light will cause eye vision decline.

Six, easy to produce harmful gases and smoke. Because the arc temperature generated in the welding process reaches more than 4200℃, the coated electrode core, coating and metal weldment will vaporize, evaporate and condense after melting, resulting in a large number of manganese-chromium oxides and harmful smoke and dust; At the same time, the high temperature and strong radiation of arc light will also produce toxic gases such as ozone and nitrogen oxides in the surrounding air. Engaged in welding work under poor ventilation for a long time, these toxic gases and smoke are inhaled by human body, which has a certain impact on human health.

Seven, easy to cause falling Due to the needs of construction, welders should often climb the welding work. If the anti-falling measures are not done well, the scaffolding is not standardized and will be used without acceptance; Take isolation measures when crossing up and down to prevent objects from hitting; Welders have a weak sense of personal safety protection, and they don't wear safety helmet or safety belt when climbing. In case of careless walking and accidental object collision. , may cause a fall accident. Eight, easy to cause poisoning, suffocation welders often enter metal containers, equipment, pipelines, towers, storage tanks and other closed or semi-closed places for welding. If toxic and harmful media and inert gases are stored, transported or produced, once the work management is poor and the protective measures are not in place, it is easy to cause poisoning or suffocation of the operators. This phenomenon mostly occurs in oil refining, chemical industry and other enterprises.

Nine, the general principle of electric shock prevention measures is to take safety measures such as insulation, shielding, isolation, leakage protection and personal protection to prevent human contact with charged bodies. The specific methods are: 1 to improve the insulation performance of welding equipment and lines.

Welding equipment and power cables used must be qualified products, and their electrical insulation performance should be suitable for the voltage level, surrounding environment and operating conditions used; Arrange special personnel to carry out daily maintenance and maintenance of the welder to prevent sun and rain, so as not to reduce the electrical insulation performance of the welder. 2. When the welding machine breaks down and needs maintenance, moving the work place, replacing the connector or replacing the safety device, the power supply must be cut off before operation.

3. Don't forget to install the leakage protector when installing the power supply for the electric welding machine, so that the guarantor will automatically cut off the power supply in case of electric shock. When welding on wet or metal containers, equipment and parts, a leakage protector with rated working current not greater than 15mA and rated working time less than 0. 1 s must be selected.

4, butt welding machine shell and the end of the secondary winding lead should take good protective grounding or zero measures. When the power supply is three-phase three-wire system or single-phase system, a protective grounding wire should be installed, and its resistance value should not exceed 4 Ω; When the power supply is a three-phase four-wire neutral grounding system, a protective zero line should be installed.

5. Strengthen the education of workers' electricity safety knowledge and self-protection consciousness, and require welders to wear insulating shoes and special insulating gloves when working. Open-air welding is prohibited in rainy days; When welding in a particularly humid place, people must stand on a dry wooden board or rubber insulating sheet.

6. It is forbidden to use metal structures, pipes, tracks and other metal connectors for wire connection. In a metal container.

5. Basic knowledge of electric welding

A, welding:

It is a method to connect two workpieces by using heat energy or pressure, or both, with or without filler. Second, the manual arc welding classification:

Flat welding, horizontal welding, vertical welding and overhead welding.

Third, safe operation.

1, electric shock prevention: check whether the welding machine is well grounded before work; Check whether the electrode holder cable is in good condition. Special attention: 380 volts behind the welder.

2. Prevention of electric arc burns and scalds: Arc light contains a lot of ultraviolet rays, infrared rays and strong visible light, which has * * * effects on eyes and skin. Do not touch the welded workpiece. When tapping welding slag, use proper force and pay attention to the direction.

3. Protective equipment: welding mask, leather gloves and rubber-soled shoes.

4, equipment safety, AC arc welding machine, electrode holder don't put on the worker or workbench, in order to avoid short circuit, burn out the welding machine. If you find a high fever or a burning smell at work, stop working immediately, turn off the power and report to the teacher.

5, self-prevention of eye burns: human milk drops, eye drops, cold and wet towels are applied to the eyes.

Fourth, the process

1, currently selected:

2.5mm Recommended value 70-90A

Formula: I(A)=K*D(mm)

Empirical coefficient k:

Diameter 1—2 3—4 5—6

k25-30 30-40 40-60

2. Arc striking

Contact method: Gently contact by friction method, and quickly lift 2-4 mm..

3. Shipping

Grasp that the angle of covered electrode is basically perpendicular to the workpiece, and the advancing direction is inclined by 5 degrees-15 degrees.

Forward speed: slow, straight forward at a constant speed.

Feed speed (arc length)

4, lateral swing (widen the weld)

Broken line, half moon, circle

Step 5 pause at the beginning

6. After the arc is broken, cool the arc again.

Verb (abbreviation of verb) Note:

1. Before welding, check whether the welding machine is well grounded, and the insulation between the electrode holder and the cable must be good.

2, when welding should stand on the board, no barefoot operation. It is forbidden to touch the conductive part by hand to prevent electric shock.

3. In order to prevent harmful ultraviolet rays and infrared rays, gloves and masks must be worn to prevent arc injuries and burns.

4. Pay attention to the direction of slag discharge to prevent welding slag from flying out and hurting people.

5. After welding, the workpiece is not allowed to be held directly by hand, and it should be clamped with iron tongs.

6, oxygen bottles, argon bottles and carbon dioxide bottles shall not impact and baking exposure.

7, oxygen bottle mouth is not allowed to have grease or other flammable, wrench can not have oil.

8, acetylene bottles are not allowed to have Mars around, oxygen bottles should be placed at a certain distance.

9, after the internship to clean up the scene and equipment and tools.

Six, equipment safety:

1, the connection points of the lines must be in close contact to prevent heating due to looseness and poor contact.

2, electrode holder shall not be placed on the workbench at any time, so as to avoid short circuit burning out the welding machine.

3, found that the welding machine or circuit fever, should immediately stop working.

4, after operating or checking the welding machine and circuit system must switch, turn off the power supply.

6. Welder safety knowledge

Causes of fire and explosion accidents in welding operation

(1) During welding and cutting operations, especially during gas cutting, Mars, molten beads and iron slag are splashed everywhere due to the injection of compressed air or oxygen flow (larger molten beads and iron slag can splash to a place 5m away from the operation point). When inflammable and explosive substances or gases exist in the working environment, fire and explosion accidents may occur. (2) During high-altitude welding and cutting operations, inflammable and explosive articles within the reach of Mars are not cleaned up, and workers throw a covered covered electrode head during the operation, and do not carefully check whether there is fire after the operation. (3) No acetylene generator was placed during gas welding and gas cutting, and the safety devices of welding (cutting) torch, rubber pipeline and acetylene generator were not checked as required before work. (4) There are defects in the formulation, storage, filling, transportation and use of gas cylinders, which violate the safety operation procedures. (5) The formula and installation of acetylene, oxygen and other pipelines are defective, which were not found and rectified in time during use. (6) When welding and repairing fuel containers and pipelines, corresponding measures were not taken as required. In the implementation of replacement welding repair, the replacement is not complete, and in the implementation of non-replacement welding repair with pressure, the pressure is not enough, which leads to the introduction of external open flame.

Preventive measures of fire and explosion accidents in welding operation

(1) During welding and cutting operations, all inflammable and explosive articles within the scope of l Om in the working environment should be cleaned, and attention should be paid to whether there are flammable liquids and flammable gases in the trenches and sewers in the working environment, and whether it is possible to leak flammable and explosive substances into the trenches and sewers, so as to avoid disasters and accidents caused by welding slag and metal sparks. (2) When welding and cutting at high altitude, it is forbidden to throw covered electrode's head, and the lower part of welding and cutting operations should be isolated. After the operation is completed, you should carefully check and confirm that there is no fire hazard before leaving the site. (3) Gas cylinders that meet the requirements of relevant national standards and regulations should be used, and the storage, transportation and use of gas cylinders should strictly abide by the safety operation procedures. (4) Pipes conveying combustible gas and combustion-supporting gas shall be installed, used and managed according to regulations, and operators and inspectors shall receive special safety technical training. (5) When welding and repairing fuel containers and pipelines, the welding and repairing methods shall be determined according to the actual situation. When implementing the replacement method, the replacement should be thorough, and the shadow of combustible substances should be strictly controlled in the work. When the pressureless replacement method is implemented, a certain voltage should be maintained as required. Oxygen content should be strictly controlled in the work. It is necessary to strengthen detection, pay attention to monitoring, and have safety organization measures.

7. Basic knowledge of electric welding

1 Basic knowledge and skills of electric welding 1: The arc temperature of argon arc welding is generally between plasma arc and manual arc welding, the arc temperature is 9000- 10000K, plasma arc 16000-32000K, manual arc 5000-6000K, and melting electrode argon arc. Noise causes hearing loss.

2. Electric welding is the heteropolar (positive or negative) between the workpiece and covered electrode power supply. The instantaneous contact between covered electrode and the workpiece ionizes the air to generate an arc, and the arc temperature is very high, about 5000-6000K, which melts the surface of the workpiece to form a molten pool. After melting, the coated covered electrode metal is coated on the surface of the workpiece to form metallurgical bonding. 3. "Oxyacetylene Flame" refers to acetylene in oxygen (acetylene is commonly known as calcium carbide gas, which reacts with water). In this reaction, a lot of heat is released, so that the temperature of oxyacetylene flame can reach above 3000℃, and steel will melt soon when it comes into contact with oxyacetylene flame.

Using this characteristic, oxyacetylene flame is often used to weld or cut metal in production, which is usually called gas welding and gas cutting. Gas welding; The high temperature of oxyacetylene flame is used to fuse two metals together. The key is to prevent metals at high temperature from being oxidized by oxygen in the air. Therefore, the amount of oxygen must be controlled to make acetylene burn insufficiently.

In this way, the flame is reducible because it contains carbon monoxide and hydrogen produced by incomplete combustion of acetylene. This kind of flame makes the metal parts and covered electrode to be welded not be oxidized to change their composition when melting, and the weld will not be polluted by oxides ... 4. Water welding should be a welding process under special conditions. 5. The temperature of oxyhydrogen flame can be as high as 2500~3000℃, and even the high melting point (melting point is 17 15℃) can be melted under oxyhydrogen flame combustion.

Therefore, oxyhydrogen flame can be used to process timely products. C2H2 flame and HO flame have different applications. O of HO flame is strongly oxidizing. In some cases, HO flame is not used to prevent metal from being oxidized during welding.

On the contrary, C with valence of-1 in C2H2 is reducible. C2H2 flame can be used not only for welding metal, but also as a protective gas to prevent O in the air from oxidizing the welding metal. Covered electrode: E43 and E50 series welding machines are commonly used: The working principle of ordinary welding machines is similar to that of transformers, and they are step-down transformers. At both ends of the tooth and the coil are the welded workpiece and the coated electrode, which ignite the arc and fuse the gap between the workpiece and the coated electrode at the high temperature of the arc.

Welding transformer has its own characteristics, that is, the voltage drops sharply. Covered electrode voltage drops after ignition; When the covered electrode is short-circuited due to adhesion, the voltage also drops sharply.

The reason for this phenomenon is the iron core characteristics of welding transformer. The working voltage of the welding machine can be adjusted not only by a 220/380 voltage conversion, but also by the tap of the secondary coil. At the same time, it can be adjusted by iron core. The more the iron core enters, the smaller the welding voltage will be.

The working schematic diagram is similar to that of transformer, so it is not drawn here. Suggestions on becoming an excellent welder: 1.

First of all, there are more than 100 welding methods, mainly manual welding (that is, the one that burns covered electrode); Resistance bump welding; Gas shielded welding (carbon dioxide and argon arc welding, etc. ); Flame welding; Ultrasonic welding, friction welding, etc. Commonly used welding technologies are argon arc welding, carbon dioxide welding and manual welding.

You need to go through formal welding training and obtain a welder's certificate before you can go to work. 3。

Due to certain technical and skill requirements, the effect and quality of products welded by welders of different levels vary greatly. The salary of a truly high-level welder (national level) is very high.

The average welder in Guangdong has a minimum income of about 1.500 yuan, and the piece rate may be higher. 4。

Welders should have good occupational protection measures when operating, such as gloves, masks, shoes, aprons, underwear and glasses. So don't worry about danger.

As long as you follow the rules, it is safe.

8. Common sense and methods of welders. Safe operating procedure

Welder safety knowledge and methods, the operating steps are as follows: 1. You should master general electrical knowledge, observe the general safety regulations of welders, and be familiar with fire fighting technology, electric shock first aid and artificial respiration.

2. Check whether the power cord, lead-out wire and connection point of the electric welding machine are in good condition before work, and the line crossing the roadway should be overhead or covered with protective cover; The secondary circuit and shell of electric welding machine must be well grounded; The covered electrode clip must be well insulated. 3. Open-air welding is not allowed in rainy days. When working in wet areas, you should stand where insulating articles are placed and wear insulating shoes.

4, mobile welding machine from the power grid wiring or inspection, grounding work must be carried out by an electrician. 5. When pushing the knife switch, the body should be skewed, and the feet should be pushed at one time, and then the welding machine should be turned on; The welding machine must be turned off first, and then the power switch can be unplugged.

6, mobile welding machine position, must first stop the power supply; If welding stops suddenly, please turn off the welding machine immediately. 7. When welding in crowded places, a fence should be installed to block the arc light. When there is no fence, remind people around you not to look directly at the arc light.

8. Wear gloves when replacing covered electrode, and don't lean on iron plates or other conductive objects. Wear protective glasses when tapping slag.

9, when welding non-ferrous metal equipment, should strengthen ventilation detoxification, use filter gas mask when necessary. 10. In case of gas leakage, when repairing the gas pipeline or welding, you must inform the gas station and the fire and safety department in advance and get permission before you can start working. Before work, the gas source must be turned off and ventilation should be strengthened to eliminate the blown gas.

1 1. Turn off the welding machine after work, and then disconnect the power supply.

9. What safety knowledge should welders pay attention to?

Original publisher: two-way film is flying

Precautions for welder before operation: 1. Welders must undergo professional training and pass the examination before taking up their posts. Non-welders are prohibited from engaging in welding operations. 2. Wear safety protection articles such as welding overalls, insulating shoes, welding gloves and protective masks during operation. 3. Before operation, check the welding machine and tools, such as the insulation of welding tongs and welding cables, the protective grounding of the welding machine shell and various connection points of the welding machine. Before operation. 4. Before welding on the equipment, the grounding wire or neutral wire of the equipment should be removed first, and then restored after welding. 5, before welding operation, should check the working environment, remove dangerous and harmful factors, and set up a guardian. It is strictly forbidden to weld or cut stress members in the diffusion area of flammable and explosive gases, in the running pressure pipeline and in the container containing flammable and explosive materials. When there are other people and related facilities nearby, screen protection and safe interval should be adopted to ensure the safety of operation. 6. In the welding workplace, there must be fire prevention equipment, such as fire hydrants, fire extinguishers, sand boxes and buckets filled with water. 7, before welding operation, must go through the formalities for examination and approval of hot work, examination and approval is completed before operation. 8, welding operations, wiring operations must be carried out by a professional electrician, it is forbidden to pull disorderly connect. During operation: 1, inflammable and explosive articles shall not be stacked around the welding operation site 10 meter; 2. Outdoor operation is not allowed in rainy, snowy and windy weather above Grade 6. After rain and snow, water and snow should be removed before operation. 3. When the welding site is wet or the clothes of the welder are wet after sweating, it is forbidden to lean against the charged steel plate or workpiece. Welders should work on dry insulating boards or rubber mats, and personnel should wear insulating shoes or stand on insulating boards. 4. When welding in narrow workplaces such as metal containers and metal structures, the risk of electric shock is the greatest, and special protective measures must be taken. If you use a rubber pad, put on leather gloves and put them on.

10. What are the welding skills?

I. Custody of covered electrode:

1, all kinds of covered electrode must be stored by classification and brand to avoid confusion. At the same time, it should be stored in a dry and ventilated warehouse and placed at a distance of not less than 300 mm from the ground and walls to prevent deterioration due to moisture.

2. Because the coating is easy to be affected with damp, the process performance of covered electrode becomes worse after being affected with damp, and the hydrogen in the moisture is easy to cause pores and cracks in the weld, so covered electrode must be dried before use to reduce the hydrogen content of covered electrode, generally 350~450? ; , heat preservation 65438 0 ~ 2 hours, drying.

Second, the operation:

1. After the workpieces are assembled, spot-weld firmly before welding. The width-height ratio of the weld is 2~3, and the width of the weld is generally 1.5~2 times. Initial welding refers to the part that has just started welding. After arc initiation, the arc should be slightly lengthened, the welding end should be preheated, and then the arc length should be appropriately shortened for normal welding.

2. End of weld means that when the weld ends, the arc pit at the end should be filled. If the arc is broken immediately at the end, an arc pit below the surface of the weldment will be formed, which will weaken the strength of the weld end and lead to cracks. So there is no arc pit at the end, and the arc pit should be filled up.

3. Due to the limitation of the length of covered electrode, sometimes covered electrode can't finish welding. The starting point of the weld required to be welded first is slightly lower. When connecting, start the arc ignition slightly before the starting point of the weld, slightly lengthen the arc to lead the arc to the starting point, cover the end of a weld, and then move along the welding direction after the starting point weld is leveled.

4. Generally speaking, zigzag or crescent-shaped strip conveying method is used for the width of weld. This method has the advantages of high weld strengthening, good metal melting, long heat preservation time, gas evolution and slag floating to the surface easily, which is beneficial to improve weld quality.

Welding thickness: the first layer of weld and other layers of weld.

Covered electrode Diameter Welding Current (A)

≥6 4 160~2 10 4 160~2 10

5 220~280

When welding the second layer, the slag of the first layer should be removed first, and then the welding should be carried out with a larger diameter covered electrode and a larger welding current. In order to ensure quality and prevent deformation, the welding directions between layers should be opposite and the welded joints should be staggered.