Wednesday, 4 June 2014

Pipe Reality Come True

My previous main steam pipe article was at the stage of it being persuaded into a shape that should fit. In practice, it wasn't that easy.

The first challenge was that, being such an awkward shape, it would have been easy for Sentinel to make it fit with 7109, the pipe and all tooling collocated in the factory. With the pipe being made five miles from 7109, it could only be made to approximately the right shape using a jig made using the old pipe geometry. Mendip Steam's Andy Melrose eventually gave in that some heat was going to be needed in the cab to make it fit. Thus 7109 had her first fire lit since 1968!
First fire in 46 years
Not much steam was created but it did seemingly allow the pipe to ease into place, or so we thought.

Everything was fine until the second challenge. The nice new end pieces were made to drawing size but that did not mean to say that the original mating joints were made that way.
Nice new end fitting exactly to drawing size
The mating end under the water tank had at one time been repaired and the hole into which the new pipe had to fit was not actually round! The two parts would not fit together.

There was nothing for it but to grovel about underneath with a miniature grinder (it's not made for a human to squeeze under the water tank) and make the mating hole bigger, not a lot of fun!
The underneath end finally in place
The fitting in detail...
...fed by a pipe around the firebox...
...fed from up here in the cab...
...from the regulator all the way up here!
So the pipe is at last in place. The white insulation is made from glass fibre ladder tape wound over partly dry, tacky red oxide paint to keep it in place. Finally the ends and a centre join are secured in place with galvanised wire.
Glass fibre ladder tape
The pipe joints are sealed using 3mm thick annealed copper washers, made from copper sheet, with lashings of SteamSeal. The copper washers were made by cutting the outer perimeter with a hole saw and the inner hole with a screw tightened hole punch. Glad I wasn't in a hurry for these, it took ages.

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