High density conventional polythene is a white and translucent thermoplastic resin. At room temperature its density is normally between 0.94-0.96 g/cm3 and its structure is about 60% crystalline: the remainder is amorphous. Between 125-135°C, depending on the density, polyethylene is totally amorphous, and is considered molten, even if in reality it has become a rubbery mass whose fluidity varies with its molecular weight. In this molten state, its density drops to about 0.80 g/cm3. It is also interesting to know how polyethylene behaves with regards to the chemical agents found where it is laid. The polyethylene Faraplan uses to produce the corrugated pipe resists most chemicals and solvents. Only a few substances such as decahydronaphthalene or any aromatic or halogenated hydrocarbons can dissolve the polyethylene at high temperatures. Chemical destruction of the polyethylene can only take place under the action of strong oxidizing agents such as fuming nitric acid or fuming sulphuric acid.