Looking at the mod data, base_area is 0.5 for the small pipes.

In the screenshots I have several types of modded pipes lined up, each containing a small amount of sulfuric waste water. From the left we have brass (5), iron (10), stone (20), steel (10), plastic (20), brass (5), and titanium (10). The pipes of size 10 or greater behave normally, and the fluid ...

I'd just joined a multiplayer game (confirmed unmodded server) when my game froze completely. I wasn't doing anything unusual, just walking while zoomed out. Then suddenly it was completely unresponsive. No sound, graphics frozen. Waited a bit, nothing.

Tried to close the window. Nothing. Killall ...

The downside to this would be that they'd be impossible to stack once they've been used once.

The workaround we found was to blow up the train. I've been able to connect and play since it was destroyed.

This train got me too. I tried to click on it, and Factorio terminated. I tried repeatedly to reconnect and the game terminated each time. I don't have a screenshot but my view was basically the same as Plawerth's.