Patent ID: 8519034

Claim:
A method for increasing the lifetime of a pipe made of a polyethylene composition which is in permanent contact with chlorinated water comprising using only two antioxidants in said polyethylene composition, one antioxidant being compound (A) and the other antioxidant being compound (B), wherein compound (A) has the following formula (I): wherein R 6 , R 7 and R 8 independently are non-substituted or substituted aliphatic or aromatic hydrocarbyl radicals which may comprise OH-groups, X 1 , X 2 , and X 3 independently are H or OH, with the proviso that at least one of X 1 , X 2 and X 3 is OH, and the entire molecule does not comprise an ester group; wherein compound (B) has the following formula (II): wherein R 1 , R 2 , R 3 , R 4 and R 5 independently are H, or non-substituted or substituted aliphatic or aromatic hydrocarbyl radicals which may comprise heteroatoms, wherein the base resin of said polyethylene composition consists of a polyethylene homo- or copolymer; wherein the concentration of compound (A) in the polyethylene composition is from 3300 to 3900 ppm; and wherein the concentration of compound (B) in the polyethylene composition is from 350 to 700 ppm.