DN1200 Butt Weld Pipe Fittings

Equal tee is widely used in petrochemical, oil and natural gas, liquefied gas, fertilizer, power plant, nuclear power, shipbuilding, papermaking, pharmaceutical, food sanitation, urban construction industries of engineering construction and maintenance. The pressure of this kind of pipe is high in the industry, the pressure can reach 600 kg, the water pipe pressure in life is lower, generally 16 kilograms.

Equal tee is on both ends of the same diameter, reducing tee branch pipe is called with other two different diameter reducing tee, said method is as follows: for equal tee, such as "T3" said three general principles of the outer diameter is 3 inches equal tee. For different diameters, such as "T4 x 4 x 3.5", the same diameter has a diameter of 3.5 inches.

The material is generally 10# 20# A3 Q23 20g 20g 20g 16Mn ASTM A234 ASTM A403 etc., three-way, the outer diameter range is 2.5 "-60", from 26 "-60" to welding tee. Wall thickness of 28-60 mm.

The stress levels are sch-5s, Sch10s, Sch10, Sch20, Sch30, Sch40s, STD, Sch40, Sch60, Sch80s, XS; Sch80, Sch100, Sch120, Sch140, Sch160, XXS.

How do I weld the equal diameter tee?

It is a kind of resistance welding method that USES the resistance heat to weld the two workpieces together at the same time. The high productivity and easy automation of welding are widely used. Its application can be summarized as follows:

(1) butt welding of the workpiece, such as steel, profile, wire, reinforcement, rail, boiler tube, oil and natural gas conveying, etc.

(2) butt welding of ring workpiece, such as the butt welding of car rim and bicycle, motorcycle wheel ring, and welding of various links, etc.

(3) the welding of parts shall be simple rolling, forging, stamping or machining parts to be welded into complex parts to reduce costs. For example, the welding of the car orientation shaft shell and the rear axle housing, the welding of various connecting rods and rods, and the welding of special parts.

(4) welding of foreign metals can save precious metals and improve product performance. Such as work part of the tool (HSS) and tail (medium carbon steel butt welding, internal combustion engine exhaust valve head (heat resistant steel) and tail (steel) butt welding, butt welding of aluminum copper conductive coupling, etc. Butt welding is divided into two kinds: resistance butt welding and flash butt welding.

The internal resistance of the workpiece is proportional to the resistivity of the welded metal and the length l0 of the electrode, which is inversely proportional to the broken area of the workpiece.

The contact resistance of the resistance and other diameter tee is determined by the surface status, temperature and pressure of the contact surface. Contact resistance is high when contact resistance has obvious oxides or other stolen goods. The increase of temperature or pressure will cause the contact resistance to decrease due to the increase of actual contact area. At the beginning of the welding, the current density at the contact point is high; The contact resistance decreases rapidly after the end surface temperature increases rapidly. When heated to a certain temperature (600 degrees of steel, 350 degrees of aluminum alloy), contact resistance completely disappeared.

As with spot welding, the heat source of welding is also the resistance generated by resistance. When the resistance is soldered, the contact resistance exists at a very short time, producing less than 10 to 15 percent of the total heat. But this heat is generated in a very narrow area near the contact surface. As a result, the temperature of this area is rapidly increased and the internal resistance rapidly increases, and even if the contact resistance is completely eliminated, the thermal intensity of the area is still higher than that of other places.

The harder the welding conditions are, the more the current and the shorter the current. The smaller the workpiece, the more obvious the influence of the contact resistance on heating.