FLOWLINE 302 is a unique lining process whereby a special polyethylene base material is bonded to steel piping and fittings. Being bonded to the metal, it does not have the tendency to collapse during temperature variations as in the case of a loose liner. The lining is formed by means of a powder fused together in the pipe, building up a lining throughout and covering the full face of the flange by means of a rotational moulding process.
FLOWLINE 302 is particularly useful because of its insolubility in, and inertness to, a wide range of chemicals. It is resistant to attack by inorganic acids, alkalis and aqueous solutions, which cause corrosion in metals. At ambient temperature, FLOWLINE 302 is almost completely insoluble in all organic solvents, although some absorption, softening or embrittlement may occur. FLOWLINE 302 is physiologically inert and can therefore be used in the food-processing industry.
OXIDATION OF FLOWLINE 302
FLOWLINE 302 decomposes in vacuum or in inert atmosphere at about 300°C, resulting in products with mainly low molecular weight hydrocarbons. When heated in air, like all other hydrocarbons, FLOWLINE 302 is oxidised at a rate depending on the temperature.
For samples stored in the dark at 20°C, no significant changes in properties have been observed after several years. For samples stored in the dark at 60°C, slow oxidation commences after an induction period of 18 months to two years.
WATER ABSORPTION AND WATER VAPOUR PERMEABILITY
FLOWLINE 302 is very resistant to water and water vapour. In fact, it is one of the best water vapour barriers available, able to maintain flexibility and water resistance even when flexed repeatedly at low temperatures.
FLOWLINE 302 has one of the lowest water absorption values of all commercial plastics. The gain in weight of a 5.3 cm disc, 1 mm thick FLOWLINE 302 immersed in water at 20°C amounts to 0.15% by weight in one year.
RESISTANCE TO ACIDS, ALKALIS AND AQUEOUS SALTS
The only acids that affect FLOWLINE 302 are those with an oxidising effect at high concentration. Thus nitric acid at concentrations greater than 30% can cause blistering. Chromic acid found in the concentration in electroplating solutions has little effect on FLOWLINE 302.
FLOWLINE 302 is highly resistant to alkalis, remaining unaffected by all concentrations of sodium and potassium hydroxide, even at 60°C.
RESISTANCE TO HALOGENS
Concentrated chlorine attacks FLOWLINE 302 severely, resulting in blistering of the surface and embrittlement. Dilute solutions of chlorine and various bleaches have little or no effect on FLOWLINE 302. Fluorine has an effect similar to chlorine. Bromine and iodine are absorbed by, and diffused through, FLOWLINE 302, degrading its mechanical properties.
RESISTANCE TO ACIDS
FLOWLINE 302 is highly resistant to caustic soda, hydrochloric, nitric [15% maximum], phosphoric and sulphuric acids and wet chlorine up to 90°C. For higher temperatures, FLOWLINE 302 can be formulated to achieve high resistance to these acids.
Pipe sizes of a 25 mm and larger diameter in 3 m lengths with flanged ends can be lined. Flanged bends, tees, reducers and fittings can also be lined. This also includes diaphragm valve bodies, butterfly valve discs and pump casings. The thickness of the lining is 2.5 mm to 3 mm. After lining, all fittings throughout are spark tested.