The outstanding chemical resistance of PVC-U extends to high concentrations; resistance against the influence of most mineral acids, bases and salt solutions and also sodium hypochlorite solutions is very good. Resistance to aliphatic hydrocarbons and elemental chlorine is also good.
PVC-U, in general, shows weakness against aromatic or chlorinated solvents, esters and ketones. Use with gases is also not recommended.
If the use of oils, varnish or fats is being considered, a prior investigation is advisable. These specifications are also valid – with exceptions – for adhesive joints, which normally are implemented by applying strongly dissolving gap-filling solvent cement to the PVC-U.
PVC-U is very resistant to weathering. Long-term influence of direct sunlight as well as the effect of wind and rain damage on the material is only superficial. Despite its very good weathering resistance regarding ultraviolet radiation, PVC-U loses some of its impact strength. In extreme applications it can be advantageous to protect the material from direct sunlight exposure.
Plastics constitute only a small percentage of the entire crude oil usage. But crude oil resources are limited. Already today we have to fall back upon raw materials which can be recycled and extend alternative energy sources. In this context we talk about re-usable raw materials.
All working processes need energy (heat, pressure, motor power). In comparison with metals, manufacturing plastics requires less energy. The production of 1 dm3 material requires an amount of energy which is given in kilograms oil equivalent per litre material in the chart below.
Compression fittings are popular because they do not require soldering, so they are comparatively quick and easy to use. They require no special tools or skills to operate. They are also used in situations where a heat source, in particular a soldering torch, is prohibited, or where it is difficult to remove remains of water from inside the pipe which prevent the pipe heating up to allow soldering.
Compression Fittings are ideal for new installations, repairs and extensions of existing water pipelines and can be integrated perfectly into numerous types of industrial applications. The compression fitting also lends itself to temporary solutions in pipe networks because it is so easily assembled and disassembled. All it takes is one simple operation to assemble and what’s more this fitting can be used repeatedly. Other applications can be found in mining, recreation parks, golf courses, camping sites, agriculture, greenhouses and irrigation systems.
Plastics are manufactured by compounding together large number of similar basic components (monomers) through chemical bonding.
The plastic industry only consumes approximately 6 % of the petroleum products originating from refineries.
To produce plastics three different processes are used:
Polymerisation is the most frequently used procedure for the synthesis of plastics. Polymerisation means the lining up of macromolecule chains without separation of foreign matter.
For example polyethylene, polybutene, polypropylene, polyvinylchloride and other plastics are all produced by means of polymerisation.
During polycondensation similar and dissimilar monomers are lined up to become macromolecule chains, at the same time separating a by-product, e. g. water, hydrochloric acid, etc.
Polycondensation is applied, for example, to produce phenolic resins and polyamids.
During polyaddition macromolecules are created from chemically different molecules, however without separating a by-product.
The procedure is used for the production of polyurethanes and epoxy resins.
The power generated by the wind turbine is in AC mode and to prevent energy loss in the transfer of power the current is converted to DC through the transformer.
During the AC to DC current conversion there is heat generated and cooling is required to minimise the energy lose and prevent the turbines from catching fire. Typically during this current transfer about 1% energy loss occurs.
Material Requirements on the distribution system for wind turbines
- Dielectric strength
Combination of ac and dc voltage stress put high requirements on purity and insulation properties of the material
- Mechanical strength
High and stable mechanical strength is required to give freedom in choice of geometries and shapes for details of the piping system.
Good machinability allows for complex geometries and narrow tolerances to ensure long term tightness of the system
- Weld ability
Good and stable welding properties with material strength comparable to the base material gives high freedom in design of the system
- Material stability
With a required design life time of plus 30 years, in an environment with high temperature and high mechanical and electrical stress, the material must show a high degree of stability in order to ensure long life.
The handling of large amounts of power gives risk for excess heat and requires a fire retardant material to limit the consequences of a system malfunction.
The cooling manifold is typically supplied in stainless steel. Given the corrosion for stainless steel near the sea it can be replaced by a PVDF assembly. Some of the advantages of PVDF include excellent mechanical /electrical properties, effective shaping and welding properties and excellent machinability.
The current from the wind turbines is fed into a distribution centre as a DC current and then fed into the electrical network as an AC current for the retail market.
Electrical cables reach temperatures of 400C and need to be cooled to minimise energy lost. They can be cooled with running cold water through a surrounding PE100 pipe through heat transfer. As the water heats up it is passed through a heat exchanger and cooled again in a continuous closed loop.
Due to its non-polar nature as a hydrocarbon of high molecular weight, polyethylene shows a high resistance against chemical attack. PE is resistant to acids, alkaline solutions, solvents, alcohol and water. Fat and oil swell PE slightly. PE is not resistant against oxidising acids, ketones, aromatic hydrocarbons and chlorinated hydrocarbons.
For additional information, please refer to the detailed list of chemical resistance tool on the GF Piping Systems website.
If polyethylene is exposed to direct sunlight over a long period of time, it will, like most natural and plastic materials, be damaged by the short wave UV portion of sunlight together with oxygen in the air, causing photo-oxidation. Because of this, GF black polyethylene grades are effectively stabilised against UV light by adding carbon black.
PE also has excellent resistance against abrasion. As a result, PE piping systems are used in numerous applications for transporting solids and slurries.
The medium transported basically determines the selection of valves. Pressure and temperature are important criteria. The valve best suited for a particular pressure and temperature can be determined from the technical data of the respective valve.
The selection of the material for the valve seals needs to be selected. This is best decided by consulting the chemical resistance list.
Also to be considered is compressible media.
Suitable materials for compressible media are those that under standard conditions and at low temperatures do not tend toward brittle fractures owing to their ductility.
Such materials include polyethylene (PE) and acrylonitrile-butadiene-styrene (ABS). All other raw materials such as polypropylene (PP-H), polyvinyl chloride (PVCU/-C) or polyvinyliden fluoride (PVDF) are to be limited to ≤ 0.1 bar with respect to the operating pressure of gases. Higher pressures are possible if secondary containment piping systems are used (for environmental protection, brittle effects, gas shocks, intoxication).
Georg Fischer Piping Systems would like to wish you a safe and enjoyable Christmas, and New Year. We look forward to a busy 2014 for all.
Please note that our blog will be not be monitored during the festive season from COB Friday 20 December 2013, until Monday January 6, 2014.
Please note our offices throughout Australia will be closed from COB, Friday 20 December 2013, and will reopen for business on Thursday January 2, 2014. If you have any urgent inquiries during this time, please contact Simon Naef on 0418 214 037.
The Butterfly Valve controls flow by using a circular disk or vane with its pivot axis at right angles to the direction of flow in the pipe. The butterfly valve requires a minimum of space and is used both for on-off and throttling services.
The different markets
Because of the aggressive environment of many applications in the chemical industry, production and transport processes in this segment pose a particular challenge to piping systems regarding safety and quality. When dosing, mixing and batching chemicals – even under the most difficult conditions – good flow and linear control characteristics are basic requirements for efficient and safe processes. Contamination must be prevented in all process steps, especially surface treatment.
Integrating the right system components is therefore crucial; the butterfly valves provide high flow performance and precise process control and regulation.
The majority of all processes in microelectronics take place under strictly controlled cleanroom conditions.
Particularly high demands are placed on the consistent purity of the process water as well as the transport of ultrapure water within the manufacturing process. The butterfly valve with a consistent thermal expansion behaviour at the same time increases safety and consequently reduces the need for costly maintenance.
Economical and sustainable water treatment is becoming more and more important, especially in light of today of increasing scarcity of resources. In water treatment applications butterfly valves are mainly implemented to transport the water.
The innovative design, flow efficiency and control characteristics, for which the butterfly valves are known, are especially appreciated in cooling applications in energy production.