Analyses of Diffusion Rates through PE and Impact on Ageing

摘要

Modern district heating pipes in accordance with EN 253 consist of steel pipes insulated with polyurethane foam which is protected against environmental damage by a polyethylene casing. The casing is produced from bi-modal PE-HD material. The bi-modal material is used to make the casing resistant to environmental stress cracking for a period longer than 30 years. The present investigations show an increased permeation of gases through bi-modal PE materials compared to older types of less stress crack resistant uni-modal polyethylene.