13 November 2009
13 November 2009
The Power industry is using more and more composite materials, especially fiberglass reinforced plastics (FRP), for fluid handling: cooling pipes with sea water, fire ductworks, flue gas desulphurization (FGD) ducts, waster water pipes.
One such company to take advantage of this technology was Hankuk Fiber Glass Co. (HFG), which has successfully replaced the ash transfer pipes of power plants, made of cast iron, with composite pipes. They are primarily installed to facilitate transfer of the residual ash, a byproduct of the of thermoelectric power generation plants, which is diluted to a slurry in water.
HFG has adopted a self-developed continuous filament winding system as its manufacturing process demonstrating high productivity and quality to produce the pipes of 150-3000 mm in diameter. Ash transfer pipes are manufactured by HFG’s unique manufacturing system and are comprised of EPOVIA Vinyl Ester resin and abrasion resistant fillers. The pipes mainly installed are 300~350 mm in diameter and 15~20mm in thickness. The inner layer is manufactured by continuous filament winding by mixing vinyl ester resin with abrasion resistant fillers, wound with fiberglass.
Problems that may occur, due to abrasion resistant fillers, during this process such as poor fiber-wetting have been solved by the improvement of the resin and the manufacturing process. The outer layer is made of Vinyl ester resin only, passing through a filament winder with fiberglass and then finally cured and cut to length. For the Vinyl ester resin, EPOVIA KAYAK KRF-1001 (a low foam, pre-promoted & high heat and abrasion resistance grade of Bisphenol-A epoxy acrylate resin) recently developed by Cray Valley, was used.
Abrasion resistant fillers of alumina/silicone carbide were employed in the system. Cray Valley joined in this technical development and provided the Vinyl Ester resin. A strong technical partnership is linking HFG and Cray Valley, not only for abrasion and corrosion resistant pipes, but also for potable and sewage pipes and other high-end markets.
In the main, most of the pipes currently used are made of cast iron; however, since development of abrasion resistant composite pipes, there has been a significant improvement in durability, economic feasibility and constructability. Cast iron pipes have shortcomings such as gathering rust over time, sometimes being perforated, and can have be more expensive and a heavier weight than composite pipes. In addition, the insides of pipes become worn by the ash in the course of transfer, leading to the designed lifetime of ash transfer pipes being as short as two years.
The HFG abrasion resistant composite pipes have been installed in various coal fired, electric power plants and constructed for a design life of two years, or the same as for the current cast iron pipes. On examining some pipes that have already seen four years of use, some abrasion has been detected as noted in a small reduction in the thickness of the inner layer, however no breakage / perforations have been found, nor any leakage detected.
Manufacturers expect that composite pipes will last double the lifespan of their metal counterparts. By doubling the life expectancy of these pipes, coal fired plants using the abrasion resistant composites piping, can expect significant savings. Laboratory results of Tabor abrasion testing that compared the abrasion resistant composite pipes with the existing cast iron pipes, suggest that composite pipes might be a far better choice than cast iron by a factor of 10.
Based on the successful application of abrasion resistant pipes to small diameter pipes, HFG is extending its application to large diameter abrasion resistant pipes, with continuously increasing orders from various thermoelectric power plants in Korea. Opportunities are also arising in the nuclear power plants industry for sea water handling. Now, the worldwide power industry gets the opportunity to increase the service life of pipes with abrasion and corrosion stresses, and EPOVIA® resin is there to help them.