Capillary welding process, welded pipe production process?

When the capillary is welded with the filter drier or other pipes, due to the huge difference in the diameter of the two pipes, the heat capacity of the capillary is very small, and it is easy to overheat, which makes the metallographic grains of the capillary increase, become brittle, and are easy to break. In order to prevent the capillary from overheating, the gas welding flame should avoid the capillary, so that it and the thick pipe reach the welding temperature at the same time, and a metal clamp can also be used to clamp a thick copper sheet on the capillary, so that the heat dissipation area is appropriately increased, so as to avoid overheating.

The welding process specification, also known as WPS, should include the following:

1. Base material material;

2. Material and type of welding consumables;

3. Welding method;

4. a groove form;

5. Welding current and voltage;

6. Welding speed;

7. a welding level;

8. Preheating temperature, interlayer temperature, postheating temperature;

9. welding shielding gas;

10. Post-weld heat treatment requirements;

11. Other requirements.

What is the production process of <> longitudinal welded pipe? The production process of longitudinal welded pipe is simple, the production efficiency is high, the cost is low, and the development is fast. The strength of spiral welded pipes is generally higher than that of longitudinal welded pipes, and welded pipes with larger diameters can be produced with narrower blanks, and welded pipes with different diameters can also be produced with blanks of the same width.

However, compared to the same length of straight seam pipe, the weld length is increased by 30 100%, and the production speed is lower.

Therefore, most of the smaller-diameter welded pipes are welded longitudinally, while the larger-diameter welded pipes are mostly spiral welded.

Welded steel pipe for low-pressure fluid transportation (GB T3092-1993) is also known as general welded pipe, commonly known as black pipe. It is a welded steel pipe used for transporting water, gas, air, oil and heating steam and other generally low pressure fluids and other purposes. The wall thickness of steel pipe joints is divided into ordinary steel pipes and thickened steel pipes; The form of the pipe end is divided into non-rebar pipe (plain pipe) and rebarbed steel pipe.

The specifications of steel pipes are expressed in terms of nominal diameter (mm), which is an approximation of the inner diameter. It is customary to use inches to express that in addition to being directly used for conveying fluids, welded steel pipes for low-pressure fluid transportation are also widely used as raw pipes for galvanized welded steel pipes for low-pressure fluid transportation.

1. Ferritic stainless steel. Chromium content 12% 30%. Its corrosion resistance, toughness and weldability improve with the increase of chromium content, and the resistance to chloride stress corrosion is better than that of other types of stainless steel.

2. Austenitic stainless steel. The chromium content is greater than 18%, and it also contains about 8% nickel and a small amount of molybdenum, titanium, nitrogen and other elements. It has good comprehensive performance and can resist corrosion of a variety of media.

3. Austenitic-ferritic duplex stainless steel. It combines the advantages of austenitic and ferritic stainless steels with superplasticity.

4. Maraging stainless steel. High strength, but poor plasticity and weldability.

When stainless steel pipes and fittings are welded or cut with pressure openings, the following requirements shall be met:

1. In the process of plasma cutting of stainless steel, it must comply with the safety technical regulations of argon arc welding. When the arc stops, the weld must not be inspected immediately.

2. The argon arc welding used with pressure opening should have good natural ventilation at the welding site, or be equipped with a ventilation device that can remove toxic and harmful gases and smoke in time to maintain air circulation at the operation point. When welding, the operator should be located upwind and should work in turns intermittently; When polishing tungsten poles, it is necessary to wear dust masks and glasses. After touching tungsten electrode, wash hands and gargle in time.

The tungsten rod should be placed in a closed lead box, and should not be kept indiscriminately; When manual tungsten argon arc welding, the power supply should be DC positive; During welding, workers must wear protective equipment according to regulations. When welding in the container, protective equipment such as air helmets, air masks or gas masks should be worn; When using AC tungsten argon arc welding machine, high-frequency arc stabilization measures should be adopted, the welding torch and welding wire should be shielded with metal textile wire, and measures should be taken to prevent high-frequency electromagnetic fields from endangering both hands.

3. The "reverse connection method" should be used for welding with DC welding machine, that is, the workpiece should be connected to the negative electrode. When the positive and negative marks of the welding machine are unclear or the knob is inconsistent with the marking, it must be tested with a universal electric meter before use, and the positive and negative poles can be confirmed before operation. After stopping welding, the welding rod head must be taken out or the welding tongs must be hung firmly in the specified place, and it is strictly forbidden to put them indiscriminately.

4. In the welding of open holes under pressure, the use of self-climbing hydraulic pipe cutting machine (climbing machine) can be handled manually; Before grinding the groove and cleaning the weld, you must check the grinding wheel and its fastening condition, confirm that the grinding wheel is intact and tight, and wear goggles.

5. Pickling and passivating stainless steel workpieces should meet the following requirements:

a.Those who suffer from respiratory diseases should not engage in pickling operations.

b.The waste liquid after pickling and passivation must be specially treated, and it is strictly forbidden to discard it indiscriminately.

c.When using a stainless steel wire brush to clean the weld, the brush should be pushed from the inside to the outside, and the brush should not be brushed back and forth.

Please refer to my previous one; Pipes with welded wall thicknesses of up to 10 mm and water pressures of up to 20 kg place high demands on the welds. In cases where the diameter of the pipe is not very large, it can only be welded on one side on the outside of the pipe. This requires the butt of the pipe to be smooth, the caliber error is not boring, the groove should be standard, there should be a gap of 2 mm between the blunt edge and the blunt edge, the first pass is welded through with a relatively small hall macro welding rod, and the penultimate welding should be smoothed to pave the way for the last welding, and the last weld requires the surface to be arc-shaped, 1 to 2 mm higher than the pipe wall, so that the quality can meet the requirements and be beautiful.

During the welding process, continuous arc welding. The second weld adopts the oblique circle transport strip method, so that the weld is well formed, in order to prevent the undercut on the surface of the weld and the molten metal under the phenomenon of trembling

It has to be done. When the end of the electrode is transported to the oblique circle, the arc should be shorter.

Weld the pipe, and then slowly lead the arc to the bottom of the base hole of the weld, and the width of the transport bar is consistent: the welding current is moderate.

The butt horizontal welding of the bevel, the first weld is made of thin electrode, when the gap is large, it is advisable to use the linear reciprocating strip method, the speed is uniform, and stop for a while, that is, the original arc stays next to it, which can effectively avoid various defects, and the welding skills and precautions of the horizontal welding position are as follows, do not stop.

The slope of each oblique circle and the centerline of the weld shall not be greater than 45 degrees.

Arc welding. Process of welded pipe:

1. Preparation before welding.

Welding rods and wires should be reasonably selected according to the chemical composition and mechanical properties of the base metal, and it is necessary to check whether the quality certificate and the product are consistent before use.

The storage location of welding rods, welding wires and electrodes should meet the requirements of temperature and humidity of welding consumables, and fill in the environmental records on time. If the electrode is wet, the welding consumables should be dried according to their instructions before use.

2. Counterpart positioning of welded pipes;

The appearance inspection of the groove slope of the welded pipe should be free of defects, the groove should be clean and tidy, the gap between the joints should be uniform, and the gap should be 3 4mm;

Positioning welding should be the same as the formal welding process, and the length of the weld should be 10 15mm, the height should be 2 4mm, and not more than 2 3

The current shall not be tested on the surface of the weldment, and there shall be no defects such as arc abrasion on the surface of the weldment.

The weld of positioning welding shall not have wheel cracks and other defects, if the defects are found, they should be removed in time, and the two ends of the positioning welding bead should be repaired and ground into a gentle slope shape.

3. Pipeline welding;

Under the condition of ensuring good welding penetration and fusion, small welding parameters should be selected, short arc, multi-layer and multi-layer multi-weld beads should be used, and the temperature between the layers should be controlled below 60.

For butt welds with a diameter of DN 60mm, the welds are required to be welded on both sides.

In welding, the quality of arc starting and closing should be ensured, the arc pit should be filled when the arc is closed, and the indirect joints of multi-layer welding should be staggered with each other.

On-site welding must be set up with effective wind, rain, and snow invasion of temporary sheds.

After the welding is completed, the slag on the surface of the weld and the nearby spatter should be cleaned up in time.

Capillary welding is mainly to pay attention to.

1. What kind of metal is the material of the base metal?

2. Suitable heat source heating.

3. The most ideal soldering material, some need flux.

For example, when the capillary is a non-ferrous metal, such as copper, iron, stainless steel, nickel and other metals can be welded with a very versatile Veodin 88C welding wire and 88C-F flux, so that you don't have to worry about finding solder for each metal, and the heat source can choose an electric soldering iron, a heat gun, and a small flame spray gun.

For example, if the capillary is a white metal such as an aluminum capillary, special attention should be paid to temperature control at this time, because the melting point of aluminum itself is very low, and the welding heating tool uses the third-generation WE53 liquefied gas porous spray gun, with the low-temperature aluminum electrode Weiodin Q303 welding wire, only at low temperature welding, can the capillary be welded very safely.

Capillary welding is mainly to pay attention to.

1. What kind of metal is the material of the base metal?

2. Suitable heat source heating.

3. Crack or rubber is the most ideal soldering material, and some need flux.

For example, when the capillary is a non-ferrous metal, such as copper, iron, stainless steel, nickel and other metals can be welded with a very versatile Viodin 88C welding wire and 88C-F flux, so that you don't have to worry about finding solder for each metal, and the heat source can choose an electric soldering iron, a heat gun, and a small flame spray gun.

For example, if the capillary is a white metal such as an aluminum capillary, special attention should be paid to temperature control at this time, because the melting point of aluminum itself is very low, and the welding heating tool uses the third-generation WE53 liquefied gas porous spray gun, with the low-temperature aluminum electrode Weiodin Q303 welding wire, only at low temperature welding, can the capillary be welded very safely.