Stopping pipe expansion noise

[Mr Expansion]

I have a nightmare of a job trying to stop pipe expansion joint noise. There are 28mm copper CH pipes down a landing (at right angles to joists) that's 15-20m long, there are several branches and drops to rads. The joists are notched and felted, and the pipes have "Flexej" axials expansion joints fitted but they aren't constrained. Is it worth trying to fit something like PTFE sheet in the notches, or making wooden blocks to keep the expansion joints in-line?
Any other suggestions?

 

[Chuck]

Is it possible that the long run of pipe is bowing upwards and rubbing/pushing against the floor boards on top? Have you paid as much attention to how the branches are fixed?

BTW, what size are your joists? (Inter alia, notches should be no deeper than 1/8th of the depth of the joist.)

 

[Mr Expansion]

Is it possible that the long run of pipe is bowing upwards and rubbing/pushing against the floor boards on top? Have you paid as much attention to how the branches are fixed?

BTW, what size are your joists? (Inter alia, notches should be no deeper than 1/8th of the depth of the joist.)

I guess it's possible, especially near the expansion joints because they aren't constrained to only move axially.

The joists vary: 8x2, 8x3 and 10x2 but the area that's a problem is a short span, maybe 1500mm. The notches were made when the original galvanized heating pipe was installed and nothing has collapsed ;-)