Mod 3 - High-Temp Alloys

Module from the Materials and Corrosion Curriculum curriculum.

HIGH-TEMPERATURE ALLOYS · Learning Objectives · 1. Identify wrought and cast alloys for service above 1000°F 2. Understand creep, carburization, and metal dusting damage mechanisms 3. Select appropriate alloy for fired heater tubes and reformer internals 4. Apply Larson-Miller parameter for creep life estimation · High-Temperature Alloys for Refinery Service

Alloy	Form	Composition	Max Service Temp (°F)	Typical Application	Damage Mechanism	Notes
A 335 P22 (2¼Cr-1Mo)	Wrought pipe	2.25Cr-1Mo	1200	Hydroprocessing reactors, heater tubes	Creep, high-temp H2 attack	Most common low-alloy H2 service
A 335 P91	Wrought pipe	9Cr-1Mo-V	1200	Supercritical steam, advanced services	Creep (improved), Type IV weld cracking	Careful PWHT required
A 213 T11 / T22	Wrought tube	Same as P11/P22	1200	Heater convection tubes, boilers	Creep, oxidation	Preferred for fired heater service
A 312 TP347H	Wrought SS pipe	Nb-stabilized 347	1500	Higher-temp fractionator internals	Creep, polythionic SCC	Better creep than 304H
A 608 HP-Mod	Cast	HP (25Cr-35Ni) + microalloyed	1850	Reformer tubes, ethylene cracker coils	Creep, carburization	Most common reformer tube alloy
A 608 HK-40	Cast	25Cr-20Ni	1950	Reformer headers, SMR tubes	Creep, carburization, sigma phase	Older reformer alloy, still common
A 608 HT	Cast	15Cr-35Ni	1950	Reformer transfer lines, pigtails	Carburization, metal dusting	High Ni for reducing atmosphere
Alloy 800H	Wrought	21Cr-32Ni-Fe	1650	Convection tubes, reformer internals	Creep, sigma phase at 1100-1500°F	Solution annealed for creep service
Alloy 625	Wrought	60Ni-22Cr-9Mo	1800	Aggressive chemical environments	Embrittlement at prolonged 1200°F	Premium alloy for severe service
Alloy 617	Wrought	52Ni-22Cr-12Co-9Mo	2000	Gas turbines, high-temp heat exchangers	Creep at very high temp	Best creep strength of Ni alloys
Source: FOS Chief Files — Metallurgy folder, API 530 (Heater Tube Design), IPE-EP-10 series

Source: Materials_and_Corrosion_Curriculum_v1.xlsx · Sheet: Mod 3 - High-Temp Alloys

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