pipes under construction inside a tile heated up by surronding magma

I was building a small refrigeration system under my rocket silo, with gold radiant pipes just under the limit of the thrust heat zone (I think )

These pipes are placed inside insulated tiles which temparature is far below 1063 °C, but with magma above at more than 1063 °C.

Despite the tile could support to have a gold pipe, after my duplicants bring gold to build the pipe, 2 of these have molten !! O_o

So it seems that the material supplyed to a pipe under construction inside a solid tile heat up based on every surrounding tiles.

Astraea.sav