To upgrade the hearths you need a certain number of decorations (different for each tier). The first requirement is 4 of the comfort(?) type and pipes are that type. 4 corner pipes make a nice circle, so some people do that to fulfill the hearth requirement. I don’t know if there is more to it for this particular channel.
It's not the best solution, but if you want to see those parts, the unedited version of the run is available here: ruclips.net/p/PLi-yuBRhPpNNBDYpww1oYDJXKzKp2_pvj
what's the purpose of the "pipe donut?"
To upgrade the hearths you need a certain number of decorations (different for each tier). The first requirement is 4 of the comfort(?) type and pipes are that type. 4 corner pipes make a nice circle, so some people do that to fulfill the hearth requirement. I don’t know if there is more to it for this particular channel.
If you keep on doing this QHT on RUclips, would you please include what you purchase at the citadel?
It's not the best solution, but if you want to see those parts, the unedited version of the run is available here: ruclips.net/p/PLi-yuBRhPpNNBDYpww1oYDJXKzKp2_pvj