Large Scale Tube Sheet Fabrication and Flawless Precision Drilling

1. The Project Challenge

The client, a leading engineering procurement company (EPC) operating in the downstream oil and gas sector, required an extraordinarily large flanged tube sheet for a massive high-pressure heat exchanger array. Due to the high temperature and corrosive chemicals involved, the part was engineered using thick, solid-forged carbon steel overlaid with an anti-corrosive Inconel weld layer.

The sheer physical dimensions (over 5.5 meters in diameter and weighing 35 tons) combined with the requirement to drill nearly 6,000 perfectly aligned holes rendered this project impossible for a standard job shop. Even the slightest microscopic variation in tube-hole deviation during machining would cause thousands of dollars of titanium tubes to misalign during final field assembly.

2. The Openex Solution & Capabilities Engaged

Our heavy manufacturing team initiated a phased manufacturing plan involving intense large-scale metallurgical control and high-end metrology.

• Cladding and Face Turning: We utilized our massive Vertical Turning Lathes to flatten the carbon steel forging. The faces were machined completely parallel, establishing absolute flatness necessary for uniform drilling depth.
• Deep Hole CNC Drilling: Utilizing proprietary tooling, we utilized a massive multi-axis CNC drilling rig setup. Advanced through-spindle cooling was required to prevent overheating while drilling through both the heavy steel block and the ultra-hard Inconel layer.
• Precision Tolerances: All 6,000 holes were kept strictly to tolerances below ±0.05 mm positional accuracy. Double internal ring grooving was added to each hole to provide superior grip for tube-rolling expansion.

3. Results and Quality Assurance

Before delivery, Openex utilized large-volume Coordinate Measuring Machines (CMMs) and laser trackers to map the face of the tube sheet, verifying zero drift among thousands of complex holes. The final product was supplied complete with all Material Test Reports (MTRs), comprehensive CMM deviation maps, and ultrasonic bond testing records validating the weld clad layer.