So Mekanism is crashing due to pathfinding in the logistic pipes, which really really saddens me because I LOVE Mekanism, been using it for over a year now.
But it seems like the issue is also somewhat being caused by forge multipart.
So I wanted to submit this bug report to you.

Here's a link for the crash-log: http://pastebin.com/En865tiC
Using paste bin so I don't flood this box.

I've been experiencing this same bug. Here's my crash log:
http://pastebin.com/PVay2NA4

Fixed in development.