Petrochemical / Refining

Ethylene Cracker Radiant Tubes — High-Temperature Alloy 800H & 304H

Russia, CIS12+ tonsAlloy 800H / 304H Seamless Furnace Tubes

Ethylene cracking furnace radiant section

Project Background

A million-ton ethylene plant in Russia underwent a radiant section revamp of its cracking furnace. The furnace tubes operate at 850-950°C in hydrocarbon cracking atmospheres, enduring creep, carburization, and thermal cycling simultaneously. The original materials showed significant carburization embrittlement and creep bulging after 8 years of service, requiring a material upgrade to extend the turnaround interval beyond 5 years.

Technical Specifications

Grade	Alloy 800H (UNS N08810) / ASTM A213 TP304H
Size Range	DN50 – DN200 (2" – 8" OD)
Standards	ASTM B407 (800H), ASTM A213 (304H), API 530
Metallurgy	Grain size ASTM 3–5, 800H carbon 0.05–0.10%

The Challenge

The critical challenge for 800H furnace tubes is balancing long-term creep strength with carburization resistance. At 950°C, both creep deformation and carbon diffusion from the hydrocarbon process side accelerate degradation, leading to premature tube replacement.

TOKO TECH Solution

TOKO TECH supplied 800H tubes with precisely controlled carbon (0.05-0.10%) and Al+Ti (0.85-1.20%) content to maximize high-temperature strength. Grain size was maintained at ASTM 3-5 for optimal creep resistance. 100,000-hour creep rupture strength at 950°C meets Larson-Miller parameter requirements. Every tube underwent 100% automated UT + eddy current + hydrostatic triple inspection.

Search Keywords

Alloy 800H tubeethylene cracker furnacehigh temperature alloy pipecreep resistant tubepetrochemical furnace tube

Frequently Asked Questions

What is the difference between Alloy 800 and 800H?

Alloy 800H (UNS N08810) has a higher carbon content (0.05-0.10%) compared to standard Alloy 800 (≤ 0.10% but typically lower). The controlled higher carbon content, combined with Al+Ti additions (0.85-1.20%), promotes carbide strengthening at elevated temperatures, giving 800H superior creep rupture strength above 600°C compared to standard 800.

What is carburization in ethylene cracking furnace tubes?

Carburization is the diffusion of carbon from the hydrocarbon process gas into the tube metal at high temperatures. This causes embrittlement, loss of ductility, and reduced thermal conductivity. Alloy 800H resists carburization through its protective chromium oxide scale (Cr₂O₃) that forms on the inner tube surface.

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