Parallel Chimneys

My last chimneys article clearly raised some anxiety with Sentinel 7109's co-owner regarding the stresses that would be present in the boiler top plate if the chimney tubes were aligned purely by pushing apart the castings. I had to agree!

The alignment tool showed that the LHS pair of tubes were in fact leaning towards the RHS pair and not in line with the blast as in the photo below (looking towards the rear).

The white dot is the end of the alignment tool's threaded rod
and slightly to the right (in the photo)

This meant that the LHS tubes did need to be offset relative to their blast nozzles.

The inner mounting holes of the two LHS tubes were modified to be slots so that  the LHS tubes could be jacked apart from the RHS tubes. In this way, the LHS tubes were made parallel to the RHS ones and held in place after tightening the fixings into the casting.

Once done, both RHS and LHS tube pairs could be seen to be parallel to the vertical cab front joining strap between the RHS and LHS tubes.

Tubes all parallel to the strap between

Instinctively, this was much more satisfactory. The LHS heat shield was fitted first and then the RHS. The tubes inside RHS shield seemed to be rather offset; however, as the spacers and fixings were inserted, the whole assembly seemed to relax into place and fit surprisingly well, much to the relief of both owners.

The complete assembly in place (1)

The complete assembly in place (2)

The two damper flap are still to be fitted but otherwise a major step forward achieved!

View from the inside

View from the outside

For completeness, this is how the assembly looked in 2004:

It's come a long way!