The Luzon grid had bouts of yellow and power alerts during summer, which caused brownouts in particular areas of Luzon. Officials said this is not about the power supply situation of the country, but mainly due to scheduled power plants maintenance.
Production failures and increased maintenance costs due to corrosion-induced leakages, pipe bursts, and blocked valves are not uncommon in power plants and can result in far-reaching consequences for the operators. Plastic piping systems are a modern alternative thanks to their corrosion resistance and durability.
The power generation sector is still growing steadily from a global perspective. In many regions of the world, existing power plants cannot cover the steadily growing demand for power from industry and private households. For this reason, capacities are being expanded and modernized. At the same time, owners and operators have to increasingly pay greater attention to the efficiency of their plants in order to counter market risks and fundamental changes in power generation as well as to secure profitability.
A modern method for increasing the efficiency of new and existing plants is to convert larger parts of the piping system from metal to plastic. It is suitable both for conventional power plants as well as for regenerative forms of power generation that also use a water-steam circuit, such as biomass power plants. This step helps to lower maintenance and repair costs and to significantly reduce the risks of leakages and pipe bursts caused by corrosion in the power plant.
“Owners and operators are aware of the possible consequences of stoppages and unscheduled failures,” says Gero Meinecke, Global Market Segment Manager of Energy at GF Piping Systems. “This applies to the consequences for their customers as well as their own reputation as reliable power suppliers.” Revenue losses and penalties for breach of contract are among the possible financial consequences of pipeline problems caused by corrosion in the event of non-performance of power supply contracts.
At most power plants, about 80 percent of pipelines are still made of metal. About one third of these can be converted to plastic. Meinecke: “Changing the material offers many benefits. Since plastic pipelines are non-corrosive, they are considerably less susceptible to leakages. They last just as long as the system itself, which is at least 25 years. If the system is not continually loaded to the maximum in terms of temperature and pressure, they even last significantly longer.”
Plastics can be used for temperatures of up to 140 degrees depending on the material chosen. Meinecke: “Even the replacement of a faulty pipeline for converting to applications suitable for plastic up to a maximum range of 60 to 70 degrees. Meinecke: “This mainly comprises the primary cooling circuit and from the boiler and water treatment. Here, thermoplastics such as polyethylene (PE) and polyvinyl chloride (PVC) have proven most effective.”
Large-scale cooling water absorption from the sea, a lake, or a river requires large cross-sections that lead to the corresponding distribution points in the power plant via the pump station. Meinecke: “If it involves seawater, it must be desalinated. Cleaning and treatment is always necessary to make the water suitable for the technical processes.” Plastic pipelines are also excellently suitable for aggressive chemicals such as sodium hypochlorite: They are resistant to corrosive substances and have already been used for several decades in classic water treatment to reduce repair requirements and lower costs thanks to their high chemical resistance.
On the further route of the water within the power plant, plastic pipelines are suitable both for conventional power plants as well as for regenerative forms of power generation that also use a water-steam circuit, such as biomass power plants. In contrast, the pressure – atmospheric at first – and the temperature in the water-steam circuit increase.
However, plastic can be used up to the next necessary treatment stage, the demineralization of the boiler water, and up to the boiler. Afterwards, it can be used again for condensation and returning the condensate for treatment.
“For a long time, fibrous composite materials were regarded as the alternative to metal,” says Meinecke. “In practice, however, they have proven to be very prone to breakage due to their rigidity and brittleness. This makes laying and repairing more difficult since a lot of preliminary work is necessary, particularly when laying underground. In practice, this involves glass-fiber matting coated with resin. It makes work quite difficult, especially in the job site environment. Moreover, it requires special precautions for employee and health protection due to the solvent vapors that occur.”
Plastic pipelines are, typically for the material, flexible and thus less prone to breakage. They can be connected easily within minutes by butt fusion or electrofusion. Meineke:
“Thus, sections are perfectly feasible and do not cause any health hazards for the employees. Special respiratory protection is not necessary.” The fast installation helps to keep unscheduled downtimes as short as possible and to remain on schedule during inspections.
Plastic piping systems weigh up to 60 percent less than steel systems, which reduces the static requirements for pipe suspensions or pipe bridges in the power plant and allows faster installation. Plastic pipes can be transported without heavy lifting gear. Muscular strength is also often sufficient for larger segments. This means that the assembly and maintenance teams can work faster, more efficiently, and safely.
The quality of welds can be examined by means of modern and non-destructive test procedures. The documentation of the acquired test data is also increasingly integrated in the quality assurance on the customer side. It is always recommendable for the cost comparison between pipeline systems – here metal and plastic – to be based on the costs over the entire lifecycle (“total cost of ownership”). Apart from the initial investment, these include operating, maintenance, and replacement costs in particular. Meinecke: “In the overall analysis, plastic is nearly always cheaper since metal solutions often have to be replaced or repaired several times over the same time period due to the typical corrosion.”
In the field of solar and wind energy, plastic piping systems can be used in auxiliary applications in order to achieve the aforementioned benefits here, too. One example are the cooling water circuits within high-voltage transformers and rectifiers or inverters. In the case of wind power generation on the open sea, as in the northern part of Germany, salt water is frequently used as a cooling medium, for which plastic is excellently suited. In the case of water-cooled, high-voltage equipment, such as transformers for high-voltage DC transmission, PVDF is particularly suitable as a material for the heat exchangers. It also offers maximum safety by means of special welding methods. Meinecke: “Absolute tightness and reliability of the connections have priority here. A leakage within an electrical high-voltage installation could cause damage amounting to millions and must therefore be absolutely excluded.”
Optimizing and increasing the efficiency of a complex system with many dependencies requires a high degree of expertise and experience in planning and implementation – especially when working with new materials. Owners and operators often feel stumped and overwhelmed here at first. Therefore, it is helpful and frequently necessary to rely on manufacturers’ material and planning expertise and on complete system solutions instead of purchasing individual products.
“The desire for more innovation has been repeatedly expressed particularly with regard to new methods in power generation,” says Meinecke. “Plastic piping systems offer the opportunity to benefit from innovative materials and to increase the efficiency of new and existing plants immediately.”