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. To dramatically reduce the wear-and-tear on the frac tree, blocks at or near the top of the frac trees are strategically lined with a high-strength wear-resistant material internally at points where frack fluid or flowback changes direction to flow toward or away from the single straight-line connections.