When 2 or more steam tunnels are directly adjacent to each other or you place a machine structure block next to a steam tunnel multi-block, there is a visual bug. Likely due to machine structure blocks having connected textures. Attached is an image:

Yeah i looked into it.
And unless i am doing very drastic changes to the blocks It won't be possible to fix this.
And i attempted to fix it but failed ^^"

Sorry.