The testing methods of butt welding elbow after corrosion

Butt welding elbow in the incorrect use can produce the phenomenon of corrosion, welding curved hairs students after corrosion, usually for the butt welding elbow pipe wall thinning, local pits and pitting. Butt welding elbow after the corrosion detection methods: leakage flux method was used to detect the basic principle is based on the fundamental features of high permeability of ferromagnetic materials.
Butt welding elbow corrosion defect of permeability is much smaller in butt welding elbow permeability, butt welding elbow under the action of an external magnetic field is magnetized, when when there are no defects in butt welding elbow, the lines of magnetic force is, for the most part, through the pipe. At the same time, the uniform distribution of magnetic force lines; when butt welding elbow internal defects, the magnetic field lines are curved and part of the magnetic flux leakage of leakage of pipe surface. Detection by magnetic flux leakage magnetic elbow surface escape, you can judge the existence of defects. Ultrasonic ultrasonic testing is the use of ultrasonic pulse reflection principle to measure the thickness of the tube wall after corrosion. The process is formed by self – propagating centrifugal casting, which mainly uses the chemical reaction of the material itself, the heat release from the heat release to produce high temperature, and the technology of synthesizing the new material in the process of the spread of the combustion wave. Detection probe perpendicular to the inner wall of the butt welding elbow to emit ultrasonic pulses, first to receive the probe is composed of a pipe wall inner surface reflection pulse and ultrasonic probe and received from the tube outer wall surface reflection pulse, the pulse distance of space between the inner and surface reflection pulse reflected the tube wall thickness. Simmer bending: refers to the tube are processed into a butt welding elbow, generally refers to professional hydropower electrical metal pipe and PVC pipe threading; simmer butt welding elbow: multiple fingers to drainage professional metal butt welding elbow tubule diameter welded elbow can obtained by bending.
Cold / hot bending elbow: general small and medium size can be obtained with large diameter bending; bending needs. Bending processing generally refers to the scene. Butt welding elbow: Engineering water-supply system using the most (especially large pipe diameter) can buy finished welded elbow, processing method is stamping.
Source: Yaang Pipe Industry(

The advantages and precautions of high pressure alloy elbow

According to the production process, high pressure alloy elbow can be divided into: high pressure alloy elbow, pressing high pressure alloy elbow, casting high pressure alloy elbow, etc.. According to the connection with the pipe can be divided into: direct welding (the most common way) flange connection, threaded connection and socket connection, etc..
High-pressure alloy elbow connecting pipe is practical, new, with reasonable structure, can make the piping stress is uniform, can simplify the pipeline system, easy to operate and can save investment and can reduce the resistance of pipeline, pipeline layout optimization, is conducive to the operation cost reduction and balanced flow distribution, reduce the vibration of the pipe lines, to ensure the safe operation of the equipment and pipeline has the advantages.
Even so, high-pressure alloy elbow note also nots allow to ignore: high pressure elbow welding when, by repeated heating precipitated carbide, lower corrosion resistance and mechanical properties; high alloy welding elbow sclerosing big, easy to produce cracks. If the same type of high pressure alloy elbow welding, must be carried out more than 300 degrees Celsius, 700 degrees Celsius after the preheating and slow cooling treatment. Or should use high-pressure alloy elbow electrode; electrode for use should be kept dry, titanium calcium type should be 150 DEG C and dried for 1 hour, low hydrogen type should be between 200 and 250 DEG C dry 1 hour (do not repeat a drying, otherwise coating are apt to crack and spalling) to prevent electrode viscous oil and other dirt, lest cause the weld increase with carbon content, and the influence of welding quality; to prevent eye corrosion due to heating, welding current should not be too large, about 20% of the carbon steel electrode is less than, arc shoulds not be too long, interlayer fast cooling, a narrow weld bead is appropriate.
Source: Yaang Pipe Industry(

Production process and related technologies of reducer

Reducer is used for a pipe diameter of the pipeline. Reducer, one of the pipe for pipeline in two different diameters connected, is divided into two kinds of concentric reducer and an eccentric reducer. reducer in addition to the use of steel as raw material for the production of the size of the head, on the part of the specification of reducer also available steel plate by stamping forming process of production. reducer in pipe connection and use of good performance and the use of operation with strictly according to the standard form of use, in the use of specific divided into different kinds and types, fully demonstrated the great contribution to the operation. The forming process is usually used to reduce the size of the compression, expansion or shrinkage and expansion, and the reducer can also be used in the form of stamping. For example: the standard size for the 140mm wide door frame assembly measurement width becomes larger 141.1mm. reducer (reducer) in molding production according to certain processes and production principle of control and use, strictly in accordance with the above procedure and standards were control and use.
reducer shrinkage diameter of forming process is will and big head big endian is equal to the diameter of the tube into the forming die, through the tube along the axial direction of the blank pressing, the metal mould cavity movement along the contraction and forming. According to reducer diameter size, divided into a press forming forming or several times. In the production, the door frame assembly often appear at the level of the enterprise and the cross head interface is uneven, seriously affect the matching. Four sides of the width of the door frame width measurement are basically standard size of 0.2mm, wood moisture in 8-10%, based on the production process of moisture in the process is not in place and the South humidity is larger, the door frame width will appear than the standard size of +0.5~+1.0m. Drawing die shape with reference to the size of the inner surface of the size of the design, using the blanking die to press the sheet metal forming.
Source: Yaang Pipe Industry(

According to the field of application of different, what is the classification of welded pipe?

Welded pipe is mainly used for conveying water, sewage, gas, air, heating steam and other low pressure fluid and other purposes. According to the different application areas can be divided into: wire casing, automotive pipe, transformer tube, welded thin-walled tube, welded pipe and spiral welded pipe.
Wire casing and ordinary carbon steel welding steel tube in concrete and various kinds of structure and distribution engineering, commonly used nominal diameter from 13-76mm. Wire casing wall is thinner, most of the coating or galvanized after the use of cold bending test requirements.
Transformer for manufacturing of transformer radiator tube and other heat exchangers, made of ordinary carbon steel, flattening, expanding export, bending, the hydraulic test tube. Steel pipe to be fixed or double the length of delivery, the bending of the steel pipe has a certain degree of requirements.
Spiral welded pipe: pipe blank, and then welded pipe joints made, it can be used with a narrow strip of steel production of large diameter. Spiral welded pipe is mainly used for oil and natural gas transmission pipeline, the specification of outer diameter * wall thickness. Spiral welded pipe has one side welding and double side welding, welded pipe should ensure that the hydraulic pressure test, the tensile strength of the welded joint and the cold bending properties should be consistent with the provisions.
Welded thin-walled tube: mainly used to make furniture, toys, lamps, etc.. In recent years, with the production of stainless steel tube is widely used, furniture, decoration, fences etc..
Source: Yaang Pipe Industry (

The classification of elbows with different materials

According to the different materials, the elbow can be divided into: stainless steel elbow, alloy steel elbow and carbon steel elbow. Stainless steel elbow matrix classification can be divided into: austenitic iron ferritic (duplex) type stainless steel substrate, precipitation hardening stainless steel matrix, ferrite type stainless steel matrix, austenitic stainless steel matrix and martensite stainless steel 45 DEG stainless steel substrate.
The steel elbow of the alloy steel is used in the special position. Stainless steel elbow is different from carbon steel elbow is the main material of different materials, the chemical composition will keep the elbow for a long time will not rust, is not easy to be corroded. Carbon steel elbow is cheap, the use of large. Stainless steel, stainless steel, corrosion resistance as the main characteristics, and the chromium content of at least 10.5%, the maximum carbon content of not more than 1.2% of the steel.
Austenitic iron ferrite (dual phase) type stainless steel substrate both austenite and ferrite ferrite two-phase structure (including the content is less than 15% of the general), magnetic, by cold working the enhancing of the stainless steel.
The precipitation hardening type stainless steel matrix is an austenite or martensite structure, and can be processed by precipitation hardening (also known as aging hardening) to make the hard (strong) stainless steel.
Ferritic stainless steel matrix with body centered cubic crystal structure of the ferrite (alpha phase), magnetic, generally can not be hardened by heat treatment, but the cold processing can make it slightly strengthened stainless steel.
Austenitic stainless steel matrix to the surface of the cube structure of the austenitic structure (gamma phase) based, non magnetic, mainly through the cold processing to strengthen its (and may lead to a certain magnetic) stainless steel.
Martensitic stainless steel matrix is a martensitic structure, there are magnetic, through the heat treatment can adjust the mechanical properties of stainless steel.
Source: Zhejiang Yaang Pipe Industry Co., Limited (

Cleaning procedure and precautions for stainless steel pipe fittings

Stainless steel pipe fittings with constant use and expansion, in the specific process of using produced good operating performance, fully in accordance with the important guarantee parameters used, stainless steel pipe fittings to pay attention to certain steps and methods in the use acid washing process in need.
Method for cleaning stainless steel pipe fittings by pickling liquid:
1 cloth with brush take acid lotion, try to rub on the need to deal with the surface or bead, thick film 0.5~1mm.
2 try 20 minutes after brushing (low temperature and oxidation thickness can be appropriately extended processing time).
3 wash with clear water at last.
Cleaning liquid cleaning and cleaning stainless steel pipe fittings attention matters:
1 pickling solution is corrosive, if the skin contact, please rinse immediately with flowing water.
2 waste liquid should be treated immediately after appropriate discharge.
3 pickling solution should be kept in a cool, ventilated place.
4 suitable for industrial use.

Cleaning procedure and precautions for stainless steel pipe fittings

Source: Zhejiang Yaang Pipe Industry Co., Limited (

Five methods for processing seamless pipe bend

There are many kinds of processing methods in seamless pipe bend production, let me introduce the fifth processing methods commonly used:
Method: 1 stamping seamless elbow in production in the press by a core with a taper pipe expanding to the required size and shape.
2. Forging method: seamless pipe bend production by swaging machine will be at the end of the pipe or part shall be rushed out to the outer, commonly used swaging machine with rotary, connecting rod type, roller type.
3 rolling method: seamless elbows in production generally do not have the core shaft, suitable for thick wall pipe inside round edge. In the tube placement, peripheral roller push for circular edge processing.
4. Abscesses: seamless pipe bend in the production of a is placed in the inner tube rubber and above to punch the compression, the tube bulge forming; another method is hydraulic bulge forming, in the middle tube filled with liquid, liquid pressure to the pipe drum into the required shape, the bellows of production with the most is the method.
bending forming method: seamless pipe bend production with three methods commonly used, a kind of method that extend method, another method called stamping method, the three roller method, 3 – 4 and, two fixed roller, an adjusting and, adjust roller is fixed from finished pipe is bent.
Source: Zhejiang Yaang Pipe Industry Co., Limited (

Stainless steel tube is widely used in the market

Due to its advantages in materials, the application of stainless steel tube has been comprehensively promoted. As an important material in the pipeline. Stainless steel tube has obvious advantages in the market. Different from ordinary steel pipe, stainless steel pipe is made of alloy. Transportation, stainless steel pipe is mainly used for oil and gas transportation. Compared with ordinary transportation, pipeline transportation has more important significance.
As a result, manufacturers continue to promote it. At the same time, with the development of the city, the stainless steel tube plays the most important role in the city construction. At most, it is a new mode of transportation, which is cheaper than other means. In order to meet the market demand, the number of stainless steel tube manufacturers will continue to increase.
Now, stainless steel tubes are very popular. In the study of the stainless steel tube, we found that the stainless steel pipe has the air part, which can be used for conveying fluid, so the stainless steel tube is used in many fields. Has a good resistance performance, so in the oil, natural gas transportation is very easy and convenient. In the future, we can see more of the stainless steel tubes used in our lives.
With the development of technology, the performance of stainless steel tube also has a lot of breakthrough. People can see stainless steel tubes used in every aspect of life. Outside, in the building construction, people can see parts of the stainless steel pipe. With high utilization rate, good effect, simple manufacturing process, low waste of materials, and many countries are promoting the use of stainless steel pipe. Now, the stainless steel tube has been widely used.
Source: Zhejiang Yaang Pipe Industry Co., Limited (

The good prospect of seamless steel pipe industry

Seamless steel pipe industry maintained a strong momentum of development, is an important material of national economic development. Seamless steel pipe is a kind of economy, it is widely used in petroleum, electricity, chemical industry, coal, machinery, military industry, aerospace and other industries, the countries all over the world, especially developed countries attaches great importance to seamless steel pipe production and trade.
China’s economic growth impetus to the development of the seamless steel tube industry. From the perspective of international experience, rapid growth is not the product of all industries balanced growth, but driven by a few of the rapid growth of leading industry. Different periods of leading industry, leading industry to promote the transformation of the sustained and rapid economic growth. From the perspective of domestic experience: in the 80 s dominant industry, light industry, textile industry, etc.; In the 90 s, the leading industry is the foundation of industry and infrastructure, a new generation of household appliance, real estate, etc.; After 1997, due to the leading industry there “pause” situation, the economic slowdown. This situation finally change until 2002, a new batch of leading industries to the surface. Leading is residential, automotive, electronics, communication and urban infrastructure construction industry leaders of these are the final product properties. Among these pilot industry produced some investment industry, mainly iron and steel, nonferrous metals, building materials, machinery, chemical materials and equipment industry. The above two aspects, also caused the electric power, coal, oil and other energy industry and ports, railways, highways and other transportation industry growth. Is the industry’s rapid growth has been driving the market demand of the seamless steel pipe, promote the rapid development of the seamless steel pipe industry.
Seamless steel pipe industry and the sustainable and rapid development of domestic seamless steel tube market is currently in consumption growth opportunity. Consumption of domestic seamless steel tube will maintain rapid growth, the development of domestic seamless steel tube provides a favorable opportunity. One is the energy, transportation, petrochemical pipeline needs not reduce, high-performance varieties of rapid growth. The seamless steel tube in the energy, transportation, construction and maintenance of petrochemical facilities still occupied the position of steel market is very important. In recent years, the rapid increase of the demand for high performance and new varieties, such as high performance oil well pipe, large diameter power plant boiler pipe, corrosion resistance, low temperature resistance of petrochemical pipe and stainless steel tube, etc. Two, oil, natural gas, refined products, coal slurry, coal slurry pipeline fluid such as pipeline, especially for the demand of the high strength pipeline will rise sharply. Three is the construction rapid growth, high grade space grid tube construction demand rapid growth. Fourth, to the increasing demand for high technical content of steel pipe. Automotive, home appliances, shipbuilding, equipment manufacturing industries such as the demand of the seamless steel pipe, variety and quality requirement enhances unceasingly, all kinds of seamless steel tube is to develop in the direction of high technology.
Source: Zhejiang Yaang Pipe Industry Co., Limited (

The steel industry overcapacity has always been a time bomb

China's steel demand and Production

Despite China’s signal to reduce its excess steel production capacity, industry executives said, the country has declared a “war” metal, has produced a “devastating” to the rest of the world industry.
The steel industry overcapacity in recent years has been the industry side time bombs, driving prices down, make some steel & steel pipes enterprises difficult to survive.
China’s low cost metal producers has been widely quoted as the main reason for the excess. In particular, the world’s second-largest economy was accused of “dumping” cheap steel & steel pipes into the global market, to gain market share, because of the slowdown in domestic demand. But Beijing has denied any wrongdoing and said its cost is lower than other manufacturers.
This is war, not trade
Other countries, including India, Italy, South Korea and Taiwan, also considered contribution to the global steel surplus. Export said, every country has its own set of subsidies and problems, “caused a lot of problems, dumping steel in the international market.
However, similar to the oil industry, despite the falling demand, some manufacturers in order to support prices in 2015 before slowing production progress has been slow.
In addition, it says, the oecd economies such as China is expected to lead to the global steel industry capacity expansion, its share in the world ability is expected to increase by 2017 to 71.4%.
There is no sign that the global iron and steel production in the short term is slowing down.
According to the world steel association statistics, in March 2016, the global crude steel production is 385.7 million tons, down 3.6% compared with the same period in 2015, China’s crude steel production in March, 2016 to 70.7 million tons, up 2.9% in March 2015. In March 2016 of India’s crude steel output of 8.1 million tons, a 3.4% growth in March, 2015.
Export said, “just according to the Numbers, China is by far the biggest problem”, accusing China of not complying with the international trade rules. “If your competitiveness is based on deception international trade rules, you can’t call it their own competitiveness. There is no trade is not fair, but the war.
Source: Zhejiang Yaang Pipe Industry Co., Limited (