According to the latest report of the ChemSystems consulting company, the global PVC demand will continue to grow in 2011, but due to the continuous production of new equipment in China, the global PVC capacity utilization rate will remain low. Chemical Systems said that the global economic recession triggered by the financial crisis in 2008 had a severe impact on the construction sector, with the construction industry in Europe and North America being particularly affected. With the gradual recovery of the economy in 2010, the global construction sector has also come out of the trough and will stimulate the growth of PVC demand.

Rapid expansion of production capacity in China

Chemical Systems said that there are differences in consumption prospects and production costs in different regions, and the regional distribution of global PVC investment is also very different. Demand remains low in North America and Western Europe, coupled with higher energy prices, which dampen local PVC investment activity. Due to the rapid growth of domestic demand and the dual stimulation of the calcium carbide process cost advantage, China's PVC production capacity is growing rapidly. Relatively speaking, the slower capacity growth in other regions of Asia is mainly due to the lack of raw materials with competitive advantages and overcapacity.

In recent years, the pace of expansion of PVC production capacity in China has never been faster. In 2003, China's annual PVC production capacity was only 5 million tons, and by 2009 it had exceeded 15 million tons, accounting for nearly 90% of the global PVC new capacity in the same period. Despite the increasingly stringent restrictions imposed by environmental regulations such as carbon emissions and mercury pollution, the rate of expansion of China's acetylene PVC production capacity has not shown signs of slowing down.

In the past two years, the calcium carbide process PVC process in other parts of the world has been largely replaced by the ethylene process, but there is still an advantage in China's calcium carbide process PVC production, because this process does not require the import of ethylene raw materials, and does not need to compete for domestic limited ethylene raw materials. . The raw materials needed for this process, such as coal and limestone, are mainly concentrated in the western part of China, and the economy in these areas is still relatively backward. Investing in the local area can not only use the rich raw material resources in the region, but also stimulate the development of the local economy.

Asia is the main force of demand growth

Chemical Systems Corporation pointed out that the rapid growth of PVC demand in two populous countries, China and India, has made Asia a major driver of global PVC consumption growth. In stark contrast to this, U.S. PVC consumption has been in a downtrend channel since 2004. However, the growth in U.S. demand and the expected recovery in U.S. demand will support future growth in North America. PVC demand in Western Europe has also been relatively weak in recent years, which is determined by the higher per capita consumption in the region and the prospect of lower GDP growth. Growth rates in Eastern Europe and the Middle East are also very fast, mainly benefiting from the advantages of raw materials in these regions. The sustained demand in the South American region is benefited from the higher GDP growth and infrastructure development in the region.

In recent years, environmental protection and safety issues as well as polyethylene replacement products have had some negative effects on PVC consumption. Some countries have already enacted legislation prohibiting the use of plasticized PVC in children's toys. In addition, polyolefins can replace PVC in cables and wires as well as some special architectural applications, slowing the growth of PVC in certain areas, but the cost advantage of PVC will continue to support its consumption in some major construction areas. increase.

U.S. exports increase substantially

Due to a large number of new capacity being put into operation, the decline in domestic demand and the obvious cost advantage of ethylene-based ethylene, the export volume of PVC in North America has increased significantly in recent years. According to relevant data, the US PVC export volume has jumped sharply from 650,000 tons in 2005 to 2.7 million tons in 2010. In 2010, US PVC exports accounted for about 60% of the global total. For a long time to come, the United States will still maintain its position as a net exporter of PVC. However, with the recovery of its domestic construction market, US PVC exports will gradually decline.

For the Middle East region, the region will maintain a net import of PVC, as current demand growth in the region has exceeded the capacity growth rate. The area mainly imports PVC from East Asia.

Flux Cored Welding Wire

If welding with a solid wire is satisfactory, why use a higher priced flux-cored wire? A flux-cored wire is optimized to obtain performance not possible with a solid wire. For many welding applications like vertical-up welding, flat welding, welding over galvanized, or welding hard-to-weld steels, a flux-cored wire can do it better and faster.
Although gas metal arc welding (GMAW) with a solid mild steel wire is popular, easy-to-use, and effective for many applications, it does have limitations and drawbacks. For example, GMAW is slow for out-of-position welding. It is either limited to short-circuit transfer, which is restricted by many welding codes due to the tendency for lack-of-fusion, or pulse transfer, requiring a special welding power source. It also requires very clean steel.

The ability to add a variety of materials to the core of the welding wire allows many performance enhancements to be made. Slag formers are added to shield the weld pool and shape and support the weld. Iron powder is used to increase deposition rates. Powdered alloys are added to produce low-alloy deposits or improving the mechanical properties. Scavengers and fluxing agents are used to refine the weld metal.



FCAW: Wire Selection Based on Application



Flux-cored arc welding gas-shielded (FCAW-G) wires were introduced to the market around 1957. The flux-cored arc welding self-shielded (FCAW-S) wires were introduced to the market later, around 1961.

The core ingredients for FCAW-G wires have been formulated to obtain performance impossible to achieve with a solid GMAW wire. As all of shielding is provided by the shielding gas, the core materials may be carefully selected to maximize a certain area of welding performance, such as obtaining smooth spray-type transfer with 100% carbon dioxide shielding gas and welding speeds twice as fast in the vertical position.

The FCAW-S wires on the other hand, the core materials must provide all of the shielding. The core materials generate its own shielding gases, slag formers, and compounds to refine the weld pool. The benefits of self-shielded flux-cored wires lie in its simplicity. They may be used outdoors in heavy winds without tenting and the additional equipment required for gas shielding.


There are several popular types of flux-cored wires and how they can increase welding productivity:

For semi-automatic out-of-position welding, E71T-1 wires offer unsurpassed performance. Its fast freezing rutile slag provides the highest deposition rates in the vertical-up position, up to 7 pounds per hour, unmatched by any other semi-automatic arc welding process. In addition, the E71T-1 wires also offer an exceptionally smooth welding arc and minimal spatter, even with 100% carbon dioxide shielding gas. Argon/carbon dioxide blends are used for the smoothest arc and best out-of-position performance. These are reasons why E71T-1 is the world's most popular flux-cored wire. It is a top choice for shipbuilding, structural steel, and general steel fabrication applications.

For semi-automatic out-of-position welding without shielding gas, E71T-8 wires offer the highest deposition rates. Lincoln Electric's NR®-232 can deposit 4.5 lbs./hr. in the vertical-up position, 50% faster than other E71T-8 wires. Since this wire is self-shielded, it is widely used outdoors and in field erection of structural steel.

For semi-automatic welding in the flat position, the fastest way to join thick steel plate is with an E70T-4. It offers the highest semi-automatic deposition rates, up to 40 pounds per hour. This wire is widely used to join thick steels where there is no Charpy impact toughness requirement. This wire is also self-shielded, allowing it to be easily used outdoors.

The highest deposition rate gas-shielded flux-cored wire is E70T-1. Compared to E70T-4, they offer slightly lower deposition rates of up to 30 pounds per hour, but they offer a smoother welding arc and Charpy impact toughness properties. It offers higher deposition rates than GMAW, handles dirtier plates, and uses lower cost 100% carbon dioxide shielding gas. E70T-1s are widely used in structural steel fabrication shops.

For welding coated and galvanized sheet steels, E71T-14 is the wire of choice. The self-shielded E71T-14 wire has core materials which explode in the arc, volatizing the steel coating, minimizing cracking and porosity. The result is higher quality welds and fast welding speeds. E71T-14 wires are widely used in the automotive industry for fabricating galvanized steels.

What is the fastest way to weld hard-to-weld steels? E70T-5 gas shielded wire offer excellent crack resistance on hard-to-weld steels, such as T-1 quench and tempered steels, abrasion resistant steels, and free machining steels. E70T-5 has a basic slag system, similar to 7018 stick electrode, which removes phosphorus and sulfur from the weld metal, which can cause cracking, porosity, and poor toughness. E70T-5s have lowest diffusible hydrogen levels among the flux-cored wires, resulting in excellent resistance to delayed hydrogen cracking, as. In addition, they offer exceptional Charpy impact toughness properties.



FCAW: Wire Selection Based on Application FCAW: Wire Selection Based on Application FCAW: Wire Selection Based on Application



Flux-cored wires offer higher productivity for many mild steel semi-automatic welding applications:

E71T-1 (FCAW-G): Highest deposition rates out-of-position.
E71T-8 (FCAW-S): Highest deposition rates out-of-position without a shielding gas.
E70T-4 (FCAW-S): Highest deposition rates in the flat position.
E70T-1 (FCAW-G): Highest deposition rates in the flat position with Charpy properties.
E71T-14 (FCAW-S): Fastest travel speed on galvanized and coated steels.
E70T-5 (FCAW-G): Fastest way to weld hard-to-weld steels.

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