Good quality compression joints are superior to pushfit fittings which are problematic. When using compression use the pipe insert and wrap the olive with PTFE tape. It is by far the best approach if using plastic pipe. Compression are no more expensive that pushfit and easily demountable.athstyle Active Member. Using compression fittings on plastic pipe is fine in theory but in practise it would be a nightmare. The pipe would be spinning all over the place when the fittings are getting tightened.