R134A Relief Pipe Sizing

[BronYrAur]

I am doing a gut check on something designed by someone else. Two (2) 200-ton chillers are being installed that use R134A. Each chiller has 3 relief valves that all tie into a common header. The header is 6" pipe. That seems too large just from experience. I can't seem to find a good reference on sizing. Total equivalent length is roughly 150 feet. Any thoughts? See attached. Each machine has 894 lbs of R134A