A gas flame lance to burn in roll up flue pipes
This post is about using a gas flame lance to change the shape memory or burn in roll up flue pipes. It is an improvement on my alcohol flame lance that has been described in another post.
Note: This is just part of a 12 part series on improved stove pipe rolling. You may wish to start at Part 1 to taste from the banquet.
Introduction to the gas flame lance
To burn in a new stove pipe, most others simply use the pipe on their stove. There is mention of using an external flame in this video, but there is not much detail given. I have described the burning in of a newly formed pipe in a previous post, an alcohol flame lance, I describe the reasons for using heat memory forming and also the various method of doing it. In short, it makes the metal foil in a virgin strip of titanium or stainless steel foil ‘remember’ its new flue pipe shape when you go hot tenting and winter camping.
The alcohol flame lance was a big improvement, but alcohol is a relatively weak flame at best. It lacked strong heat output to heat the foil strongly enough in the middle of a long and wide flue pipe.
I thought that it was time to investigate using gas as the fuel in an alternative flame lance. I hoped it would make the heat treatment strong, quick and decisive.
The gas flame lance
As is my custom, I built the gas flame lance out of crappy’ steel tent poles from curbside rubbish. The tent pole connecting unions could just plug together, according to the length of the pipe required. I end-for-end the pipe during the process, so the lance only needed to reach halfway up the pipe during heat treatment.
To feed fuel gas to the lance I made a stainless steel elbow to fit onto the tent pole. The other branch of the elbow was made to receive the nozzle of the gas burner/valve assembly. I covered the normal air intake holes in the burner with some adhesive tape so that combustion would only be possible where it mixed with air at the deflector/burner unit (described below)
Below the elbow I added a pipe extension to allow the lance to be mounted by pressing the extension into the ground.
I made a small circular plate for the top of the tent pole to form a gas deflector/burner that would force the flame to form around the wall of the enclosing flue pipe.
[Add a photo of the gas deflector/burner plate]
Results and discussion of the gas flame lance
The gas flame was much more effective than the alcohol one. It provided stronger heat treatment.
The gas flame lance provides a cheap, quick, gentle and even method of developing a new memory in a virgin rollup flue pipe. It is much stronger than the alcohol lance. It also means that the careful work of forming the desired shape in a flue pipe for the first time will be easily preserved indefinitely in the foil. It also reduces the risk of crinkle damage.
When I ‘burn-in’ a virgin flue pipe, by this or any other method, I use many more retaining rings as this creates a more circular shape and more even join line.
The downside of this new memory
The downside of this new strong memory of an even tighter curvature is that it makes the metal more feisty and challenging to roll up for backpacking.
Luckily, multiple posts in this series describe various innovative and unconventional methods of flue pipe rolling and unrolling. They are quite varied, but they all can tame the feisty foil curves and make the rolling and unrolling easy.
They can make a smooth and gentle transition between the two very different curved shapes without any noisy crinkling or the damage that is done during the conventional rolling method.
Tim
