An employee was transferring water from the frac tank/settling tank to another tank. The transfer continued until sludge built up in the pipe. The employee then had to clear the sludge from the pipe. The employee blew the line out using nitrogen, at 40 to 50-pounds, then heard a leak coming from a cam-lock connection. The employee was securing the broken cam-lock mechanism when a plug shot out of the pipe and broke the employee's finger. The employee was hospitalized for surgery.