Welded semi-rigid centralisers ni ibikoresho byingenzi munganda za peteroli, kandi ubuziranenge bwibicuruzwa nibyingenzi kugirango bigerweho neza mubikorwa byo gucukura no gushimangira.Ubusanzwe, centralisers ikozwe mubyuma byo mu rwego rwo hejuru, bihenze.Ariko, binyuze muri uniq ...
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