Lessons and consequences
1. All polymers are to a degree permeable to all fluids.
2. Although vents are an obvious means of limiting the accumulation of permeated fluids
(and minimising the risk of liner collapse on decompression) they can actually cause
failure as in this case.
3. The line was replaced but this time with vent holes capped with tight fitting
polytetrafluoroethylene (PTFE) nipples (see Figure 7.9). Condensed chlorine water
was no longer in contact with the steel and the line performed well for many years.