Interspersed With Remediation Of The Old Pipe With Polyethylene Modified

The intercrossing method in repairing old metal pipes usually uses pipe-class high density polyethylene ( HDPE ) as lining plastic-underlayer pipes. Its'weakness is that the shape recovery property is not ideal and the anticorrosion property in 80癈 crude oils is so bad that it is limited in the oil pipeline on-line application.In this thesis elastomers such as nitrile rubber (NBR-40), natural rubber (NR) and ethylene propylene diene monomer (EPDM) are blended with HDPE to improve the shape recovery properties of HDPE. The influence of different kinds of HDPE, elastomers and elastomers' content on the shape recovery properties of blended system is studied; the shape recovery mechanism of HDPE and blended system is discussed; also the anticorrosion properties of HDPE and blended system in normal and high temperature during a long time crude oils is studied. Meanwhile we study the mechanical properties and the influent rule of the content of elastomer on blended system's mechanical properties. According to the shape recovery properties, the anticorrosion property to crude oil and the mechanical properties we not only choose the proper underlayer material for the intercrossing method in repairing old pipe, butalso ascertain the appropriate craftwork. At last the material and the craftwork are attempted to repair a pipe .The results show that: Firstly, all of HDPE/elastomer, XLPE, HDPE/dynamic vulcanization elastomer can obviously improve the shape recovery properties of HDPE; the shape recovery properties of HDPE/NR is the best among the three kinds of blended system HDPE/EPDlvL HDPE/NR and HDPE/NBR, but the mechanical properties and flow behavior will decrease in a certain degree. Secondly, HDPE and HDPE (2480)/NBR(15%) have the better anticorrosion to hot crude oil, and the anticorrosion of LDPE is the worst; Thirdly, the content of elastomer should be about 15 wt% if the blended system is used in the intercrossing method in repairing old pipes. HDPE-2480/NBR(15%) is fit for the pipeline of crude oil transportation, HDPE-2480/NR(15%) and HDPE-2480/EPDM(15%) are fit for the pipeline of water or gas transportation; Lastly, the cold deformation- cold recovery is the best technical condition.