Every radiant tube is designed against a rupture life, not a wall-loss allowance. Creep is what spends it, quietly, whether or not the thickness gauge notices. Why it matters Every fired heater radiant tube is sized against two numbers at once: an internal-pressure hoop-stress requirement, and a creep-rupture life at its design metal temperature, per API Standard 530. The pressure calculation gets checked at every turnaround with a thickness gauge. The creep calculation gets

The Failure That Had Nothing to Do With the Alloy Grade A heat exchanger in a refinery developed through-wall pitting within 18 months of commissioning. The tubes were specified correctly, the mill certificate confirmed the right alloy, and the installation inspection showed nothing unusual. The plant team replaced the bundle and assumed it was a manufacturing defect. It wasn't. The metallurgical testing on the failed tubes told a different story entirely. EDS analysis of the