Reducing elbows have the best pressure resistance. However, due to various factors, the actual wall thickness of the floor heating pipe is usually 100%, and under this wall thickness, all kinds of pipes can meet the requirements of floor heating, and the pressure resistance advantage of the reducing elbow pipe cannot be reflected; thermal conductivity: use The pipes used for floor heating need to have good thermal conductivity, low temperature thermal shock resistance and low temperature shock resistance.

First, the production standard of reducing elbow

The current international standard for elbows is the American national standard ANSIB16.9 and 16.28. The standard outer diameter size range is 1/2 〃~ 80 〃, generally, seamless steel pipes are used as raw materials within 24 〃, and those from 26 〃 to 80 〃 are stamped with steel plates and then welded. The maximum wall thickness is 60mm and the minimum is 1.24mm. The most used steel grades are carbon steel (20#), alloy steel and stainless steel, with a total of 24 steel grades. The CrMo steel used in the boiler is like 15Cr, and the amount is relatively large. Tee, OD range from 2.5″-60″, from 26″-60″ for welding tee. Wall thickness 28-60mm. The size range of large and small heads, conventionally, we first talk about the big head size, then the small head size, the minimum size of the large head is 0.75 〃, the minimum size of the small head is 0.5 〃, the maximum size of the large head is 60 〃, the maximum size of the small head is 48 〃, 20-60 〃 is welded, and the wall thickness is 2.8 -4.5mm.

2. Processing technology of reducing elbow

With the continuous development of the world economy and the continuous improvement of income levels, we aim to face the international advanced construction industry and shipbuilding industry and other related industries. Stamping elbows are mainly connected to pipe fittings. They can play an important role in the development of this product and set sail with world-class technology. The processing technology of stamping elbow pipe fittings has a certain process. In production, the production of reducing elbow can only be made of small diameter according to certain process technology. If the pipe size is too large, it is difficult to buy the finished reducing elbow. Use welded elbows. Because the welded elbow has more welds, the performance of all the elbows is not as good as that of the reducing elbow, and it is easy to be corroded and leaked. And because reducing elbows are produced in batches, the price is cheaper than welding elbows. Now there are precision casting elbows, which can be made of 316L, with better corrosion resistance.

Since most of the pipe fittings are used for welding, in order to improve the welding quality, the ends are beveled, leaving a certain angle and with a certain edge. This requirement is also relatively strict, how thick the edge is, the angle and the deviation range. There are regulations. The surface quality and mechanical properties are basically the same as the tube. For the convenience of welding, the steel grade of the pipe fitting and the pipe to be connected is the same.

The reducing elbow is made of malleable cast iron and is used for the connection of water supply pipes, water vapor pipes, gas pipes and oil pipelines. Specifications are 1/2-10 inches, and the products are widely used in pipeline installation, installation, and supporting services in petroleum, chemical, metallurgy, electric power and other industries. The test results of the reducing elbow and the push-pull elbow were used to detect the wall thickness of the outer arc, side arc and inner arc with a thickness gauge. The pushing speed is increased by 15mm per minute, and the curvature radius is increased by 50mm, that is, the pushing speed is accelerated, and the curvature radius is increased.

The wear and tear of reducing elbows has always been a factor affecting safe and civilized production. With the continuous development of science and technology, materials have also continued to innovate, and materials such as cast stone, cast steel, alloy, and centrifugally cast composite ceramics have appeared one after another. Reducing elbows have corresponding development plans in the development of science, and are used in accordance with corresponding technical development and performance. Among them, the pipeline is lined with alumina ceramics with its high wear resistance, high hardness, good oxidation resistance, good corrosion resistance and extremely high performance. High resistance to high and low temperature strength, has become one of the most widely used wear-resistant materials, accounting for about 80% of the world's special ceramics market share (wear-resistant materials).

3. Advantages of the manufacturing process of reducing elbows

1. Reducing elbows are suitable for pipeline systems in petroleum, natural gas, chemical, hydropower, construction and boiler industries.

2. No tube blanks are needed as raw materials, which can save the cost of tube-making equipment and molds, and can obtain carbon steel elbows with any large diameter and relatively thin wall thickness.

3. Due to the above two reasons, the manufacturing cycle can be shortened and the production cost can be greatly reduced. Because it does not require any special equipment, it is especially suitable for processing large carbon steel elbows on site.

4. The blank is a flat plate or a developable curved surface, so the blanking is simple, the accuracy is easy to ensure, and the assembly and welding are convenient.

Reducing elbow is a production technology of product parts with a certain shape, size and function by means of the power of conventional or special stamping equipment, so that the sheet material is directly subjected to deformation force in the mold and deformed to obtain a certain shape, size and function. Sheet material, mold and equipment It is the three elements of stamping processing. Stamping processing is a kind of metal cold deformation processing method. Therefore, it is called cold stamping or sheet metal stamping, referred to as stamping. It is one of the main methods of metal plastic processing and also belongs to material forming. engineering technology.

Fourth, the performance of reducing elbow

1. Long-term pressure resistance, only in terms of design stress, the pressure resistance of the national standard reducing elbow is the best. However, due to various factors, the actual wall thickness of the floor heating pipe is usually 2mm. Under this wall thickness, all kinds of pipes can meet the requirements of floor heating, and the pressure resistance advantage of reducing elbow pipes cannot be reflected;

2. Thermal conductivity: The pipes used for floor heating need to have good thermal conductivity.

3. Low temperature thermal shock resistance: PE--RT and PEX have better low temperature impact resistance. During winter construction, the pipes are less likely to be impacted and ruptured, which increases the flexibility of construction arrangements.

4. Environmental protection: PE-RT can be recycled and does not pollute the environment. However, if PEX cannot be recycled, it will cause secondary pollution;

5. Stability of processing performance: PEX has problems such as controlling the degree of cross-linking and uniformity of cross-linking. The processing is complicated and the processing directly affects the performance of the pipe.