A frac tree coupled to a wellhead is connected to either flowback equipment or zipper modules using a single straight-line connection of pipes, valves, and/or frac iron that define a straight-line pathway for fluid, gas, or flowback materials. The disclosed single straight-line connections referenced herein may be used in pressure pumping operations to deliver hydraulic fracturing fluid (“frack fluid”) to a frac tree for delivery to a wellhead or for carrying flowback from the wellhead to a flowback-collecting equipment. Using the single straight-line connections referenced herein dramatically reduces the complexity of connections needed to deliver frack fluid to or carry flowback away from a well, thereby reducing the cost, improving the efficiency, and increasing the safety of pressure-pumping and flowback operations.