作者：tjdpbdarticle

Steel gi pipe, somewhat is considered a superior product in a couple of practical applications, for it extends the service life and has a relatively low cost in use. As a rule, welding of China galvanized steel pipe is done almost exactly the same way as welding of the bare steel of the same composition. The welding industry recognized fifty years ago that welds on galvanized steel and welds on uncoated steel are of comparable strength if the quality of the welds is comparable. In recent years, more and more steel pipe manufacturers begin to pay much attention to the improving the welding technology involving weld toughness, porosity control, weld appearance, restoring corrosion resistance and other issues in a mill.

The difference between welding galvanized steel pipe and welding uncoated steel one is a result of the low vaporization temperature of the zinc coating. Zinc melts at about 900˚F and vaporizes at about 1650˚F. In addition, when it comes to hot dipped galvanized steel pipe, it can not be denied that when zinc vapor mixes with the oxygen in the air, it reacts instantly to become zinc oxide on the surface of pipe to protect steel products from rusting in use. As a rule, welding exposes everyone to similar hazards in most of cases. General hazards of welding include impact, penetration, harmful dust, smoke, fumes, heat and light radiation. Welding “smoke” is a mixture of very fine particles (fumes) and gases. Many of the substances in the smoke can be extremely toxic. The intense heat of welding and sparks can cause burns. Eye injuries have resulted from contact with hot slag and metal chips. The intense light associated with welding can cause eye damage. Ultraviolet light from an arc can cause “welder’s flash” and also skin burns. There is also a danger of electric shock. If combustible or flammable materials are nearby, the heat and sparks produced by welding can cause fires or explosions. The use of compressed gas cylinders poses some unique hazards to the welder.

In certain cases, even though the remaining zinc continues to provide some protection to the zinc-free areas, the appearance is poor, and the zinc-free areas will rust when exposed to the environment. In some cases, paints are properly applied to effectively restoring full corrosion protection to the weld areas. Generally these paints are available in either spray cans or in containers suitable for brush or spray application. However, for certain cold rolled steel pipes, for instance, they exhibit special problems when welding, mostly due to the unevenness of the coating. Edges and corners typically right where welding is being done frequently have very thick, heavy zinc deposits which may interfere with welding much more than where the zinc has been applied evenly. In addition, hot dipped products typically have rough finishes which do not top coat very well, and top coating, especially with powder topcoats, has to be done within 48hours to avoid difficulty with white rust formations.

Technically, steel pipes are long, hollow tubes that are used for a variety of purposes. They are produced by two distinct methods which result in either a welded or seamless pipe. In both methods, raw steel is first cast into a more workable starting form. It is then made into a pipe by stretching the steel out into a seamless tube or forcing the edges together and sealing them with a weld. As is known to all, the main advantage of seamless pipe is the elimination of seam-related defects. However, due to its higher cost of pipe manufacturing, the steel pipe price is relatively high by comparison with welded pipe.

Galvanized steel pipe generally has the rational cost effective in the market. Compared with other typical steel pipe coatings, such as specialized painting, powder coating, is much more labor-intensive, resulting in a higher initial cost for contractors. Besides, due to its durability and anti-corrosive properties, galvanized steel pipe can recycled and reused, which to some degree save a lot of money during the post maintenance work. Hot dipped galvanized pipe has been considered popular a lot among many users today. For one thing, the galvanization process protects the steel from rusting damage that can occur during transportation, installation and service. The zinc layer on the surface of pipe can form a barrier protection for steel products to extend the service life in applications. For the other thing, this layer is also resistant to wear and scratches, which makes the steel look more attractive.

Seamless pipe has been manufactured since the 1800’s. As a rule, according to the different production methods, seamless steel pipe has four major categories: hot rolled seamless pipe, cold rolled seamless pipe, cold drawn seamless pipe, extruded tubes. The production process for seamless pipe generally starts by steel pipe manufacturers from heating a metal billet temperature. The red hot billet is rotated and drawn by rolls over a piercing rod or mandrel. The action of the rolls causes the metal to flow over and about the mandrel to create a hollow pipe shell. The shell is then moved forward over a support bar and is hot rolled or cold rolled in several reducing/sizing stands to obtain the desired wall thickness and diameter. In addition, the hot-extrusion method involves working in the compressive-stress field. Therefore, it is characteristic of this method that high-alloy steel pipe of low deformability can be produced, as well as heavy-wall and large-diameter pipes.

When it comes to hot dipped galvanized steel pipe, the process of hot-dip galvanizing results in a metallurgical bond between zinc and steel with a series of distinct iron-zinc alloys. A typical hot-dip galvanizing line operates as follows:
◆Steel is cleaned using a caustic solution. This removes oil/grease, dirt, and paint.
◆The caustic cleaning solution is rinsed off.
◆The steel is pickled in an acidic solution to remove mill scale.
◆The pickling solution is rinsed off.
◆A flux, often zinc ammonium chloride is applied to the steel to inhibit oxidation of the cleaned surface upon exposure to air. The flux is allowed to dry on the steel and aids in the process of the liquid zinc wetting and adhering to the steel.
◆The steel is dipped into the molten zinc bath and held there until the temperature of the steel equilibrates with that of the bath.

Technically, galvanization is a process of coating iron and steel with a layer of zinc by immersing the metal in a bath of molten zinc at a temperature of around 840 °F (449 °C). When exposed to the atmosphere, the pure zinc (Zn) reacts with oxygen (O2) to form zinc oxide (ZnO), which further reacts with carbon dioxide (CO2) to form zinc carbonate (ZnCO3), a usually dull grey, fairly strong material that protects the steel underneath from further corrosion in many circumstances. Generally, hot dipped galvanized pipe has higher steel pipe price than some other ordinary types of pipe in use due to its high manufacturing cost in the market.

For the practical applications, like other corrosion protection systems, galvanizing mainly protects steel products by acting as a barrier between steel and the atmosphere. However, zinc is a more electronegative metal in comparison to steel. This is a unique characteristic for galvanizing. Specifically, when a galvanized coating is damaged and the steel product is exposed to the atmosphere, zinc can continue to protect steel through galvanic corrosion. Besides, due to its durability and anti-corrosive properties, most of cold rolled steel pipes can be recycled and reused, which to some degree save a lot of money during the post maintenance work.

With the layer of protection, pipes can be used in outdoor areas, and can withstand the harm from some of the environmental effects. Testing and studies have revealed that the average life expectancy for galvanized steel used as a typical structure material is well beyond 50 years in a rural environment and 20-25 years or more in an extreme urban or coastal setting. In that regard, contractors can confidently use this product in project. As a professional steel pipe manufacturer in China, we are committed to manufacturing various types of steel pipe for your projects. For more information, you can contact us anytime.

According to the European Steel Review, a November edition of the European Steel Review by European parliamentarians, the price base for Steel mills in most European markets is relatively stable. Big steel mills continued to push for further price increases, but buyers barely reacted. Still, steelmakers are confident that a modest price increase will take effect in early 2018. Although the distributor has successfully digested the overinflated inventory, there is no immediate buying pressure. However, supply has tightened as a result of trade measures. This, together with solid underlying consumption, continues to support manufacturers’ recommendations.

German manufacturing continued to grow strongly at the beginning of the fourth quarter. Steel consumption remains strong and car and construction companies need a lot of steel. The import quantity is mainly limited to small tonnage. Despite the lack of competitive overseas opportunities, buyers see the availability of domestic sources as sufficient to meet their needs. Benchmark prices remained largely unchanged in November, still falling short of targets set by local steel mills.

Prices in France are relatively stable. Demand is pretty good, even though orders were low in October. Buyers, who had expected prices to fall, have resumed buying. While steel mills continue to recommend increased production, customers expect no change until the end of the year.

In Italy, most fourth-quarter deals have now been finalised and prices are on par with last month’s record. There is a certain degree of uncertainty in forward pricing. Buyers are waiting for large orders. In fact, some major service centers are still preparing for the end of the year. The new import agreement is almost nil. Offers from Turkey, India and Vietnam are close to European levels.
Despite the calm in the UK market, some service centres reported a rise in activity levels in early November. The outlook for manufacturing remains positive, but car production is slowing and construction activity is falling sharply. Resale profits continue to be a problem for distributors as lower-priced old inventories continue to play a role in the supply chain. Producers have been slow to release a target price for the first half of 2018 after noticing a recent drop in trading volumes.

Demand in Belgium is strong, and while sales are shrinking, the need to reduce inventory levels by the end of the year is taking into account. The product base value of steel strip mill is stable at present. The supplier recommends a small increase in production in January 2018. However, distributors do not believe current demand justifies further rate increases. They are already struggling with their resale margins. Import prices in third countries are no longer attractive.

Spanish manufacturing grew further in October. The demand for strip mill products is stable. The underlying value remained stable in November. Orders from local mills are unlikely to improve much in the near term. A large number of imported materials, especially cold rolling and galvanized coils,cold galvanized steel pipe , are still arriving at a time when overseas prices are very competitive. New import quotations were resumed this month. Activities at the service center are rather slow.

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While U.S. politicians often fear Chinese investment stealing U.S. jobs and threatening national security, analysts paint a different picture.

People lined up to meet Los Angeles lakers star Robery horry (right) at haier at CES 2012, a consumer electronics trade show in Las Vegas, Nevada. The Chinese appliance maker employs 350 people at its south Carolina plant.
New york-based rhodium group released the latest report shows that between 2000 and 2012 of the 600 deal to China’s direct investment in the United States to support 27000 jobs, and jobs are the five copies of 10000 years ago.
The companies in question are all U.S. subsidiaries with majority stakes in China. They do not include China’s minority interests — $8bn in investment in the us over 12 years, or indirect job creation related to the construction of factories or suppliers. China steel tube manufacturer‘s new plant in Texas, for example, is expected to employ as many as 2,000 construction workers.
China’s ofdi study on employment also found that $3.5 billion in greenfield investment, or investment in new facilities, has created 8,000 U.S. jobs since 2000.
Major job creators include wanxiang, an auto-parts maker that employs 6,000 americans, mainly in Illinois. Appliance maker haier is hiring 350 people in south Carolina. Huawei, a telecoms equipment firm, and 1500 are in California, Texas and New Jersey. And a number of people, including facilities that operate in Georgia that employ more than 130 people.
The study found that Chinese investors control the majority of U.S. companies, and that 170 deals have less clear impact on U.S. companies’ mergers and acquisitions, which is “overwhelmingly positive.”
“We can’t see the evidence of asset stripping behavior, found that most of the parent company after buying American companies in China are to maintain or increase the employees,” the rhodium group, director of research at Thilo hahnemann and rhodium research analyst Adam Lysenko wrote.
Compared with the previous owner, Chinese investors especially mild steel tube manufacturer can inject money to sustain spending during the crisis, the rapid growth of the Chinese market to obtain a better opportunity, and with China’s existing business synergies and improve the value of the us. Assets.
According to the report, even if is one of the few to buy led to unemployment, nor influenced by Chinese company assets, but the value chain structure adjustment and reorganization, in response to a cost or demand changes.
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