Fabricating an 8-Meter Diameter Heavy Reactor Vessel
In the petrochemical and Oil & Gas industries, large-scale fractionation columns and pressure vessels operate under extreme internal pressures and volatile environments. Openex was contracted by a leading global energy firm to fabricate, weld, machine, and assemble a 100-meter long pressure vessel weighing over 250 tons.
The Challenge
Fabricating a vessel of this magnitude presents several critical engineering hurdles. First, thick heavy-walled steel plates (over 100mm) must be perfectly cold and hot rolled into seamless cylinders. Any slight miscalculation leads to ovality issues, preventing the flanges and end caps from mating perfectly.
Second, dealing with extreme weld distortion. With hundreds of hours of Submerged Arc Welding (SAW) taking place across a 100-meter span, mitigating thermal stress accumulation is required to keep the multi-ton structural cylinder perfectly straight and within exact ASME geometric tolerances.
Our Manufacturing Solution
We began by precision cutting SA-516 Grade 70 carbon steel. Our high-capacity heavy rolling machines were used to form the vessel sections. Due to the thickness, heavy plasma beveling was used on the seams to prepare them for extreme-penetration welding.
We positioned the heavy cylinder blocks onto massive 150-ton welding rotators. This allowed our welding booms to remain stationary while the cylinder smoothly rotated beneath them, delivering completely continuous, defect-free Submerged Arc Welding (SAW).
Following thermal stress relief (PWHT) in our large on-site furnace, the vessel was transported to our CNC machining center. Using deep-boring horizontal mills, we machined the giant connection flanges perfectly flat. Interior stainless-steel cladding and custom tube sheets were successfully fitted inside.
Results & Certifications
The project was completed under schedule. Our certified Level III NDT technicians performed 100% Ultrasonic Testing (UT) and Radiographic Testing (RT) across all primary weld seams, resulting in zero critical defects. Finally, a hydro-test was performed, and the vessel successfully passed full ASME Section VIII Code Stamping inspections before being securely loaded for ocean barge transit.
