| Popis: |
Recently, polyethylene coating steel pipe has been extensively applied to water delivery in south-east China. However, similar applications in the north-west district where is severely cold and salty are seldom reported. This paper designed the refrigeration experiment, the freeze-thaw cycle experiment and the chemical immersion experiment after freeze-thaw, to test the PE coating steel pipe's reliability in the severely cold and salty region. The result showed that, after freeze-thaw or a period of refrigeration, a small number of dark spots appeared in the coating but didn’t change with the increase of freeze-thaw cycle times and the erosion of salt. The compositions were proved to be carbon and oxygen which indicated that the spots might be relative to the cryogenic stability of the coating rather than the corrosion of matrix steel. A crack and corrosion spot also appeared in test due to the excessively thick coating and the burr in steel substrate which can be eliminated by manufacturers through improving the coating formulas, surface pretreatment and coating process. |
