Abstract: A well tube liner system includes rigid, self supporting plastic liners inserted within well tube sections and including end flanges adjacent opposed ends of the tube sections for sealing against each other and against a connecting collar when the tube sections are drawn axially together during assembly of the tube sections. An auxiliary spacer corresponding in general configuration to the flanges is provided for insertion between the flanges of liner sections to maintain the flanges in axially spaced apart and sealed condition to compensate for worn threads while retaining the same liner sections.