A387 Gr91 vs SA387 Gr22: Which Has Better Creep Resistance?

For better creep resistance at very high temperatures, A387 Grade 91 generally surpasses SA387 Grade 22, as Gr 91 is specifically designed with higher chromium (9%) for superior creep and rupture strength in advanced power generation and high-temp environments, while Gr 22 (2.25% Cr, 1% Mo) offers good creep resistance but for slightly lower, though still elevated, temperature applications like general boilers and heat exchangers, making Gr 91 the choice for more demanding conditions.

Why Creep Resistance Matters for Industrial Equipment

Creep is the slow, permanent deformation of metal under sustained high temperature and pressure-a critical failure risk for equipment operating in:

• Power generation (boilers, turbines)
• Petrochemical reforming (steam methane reformers, hydrocrackers)
• High-temperature heat exchangers (shell-and-tube, plate-type)
• Pressure vessels for thermal processing

For GNEE's shell-and-tube heat exchangers and pressure vessels, creep resistance directly impacts equipment lifespan, safety, and operational efficiency-especially in processes with continuous service at 500°C+ (e.g., hydrogen production, crude oil refining).

Chemical Composition: The Foundation of Creep Resistance

The key difference lies in alloying elements that control grain boundary stability and precipitate formation-critical for resisting creep deformation.

Creep Resistance: Quantitative Performance Data

Creep resistance is measured by creep rupture strength (the stress a material can withstand before failure at a given temperature and time). Below are industry-standard values (ASTM/ASME data) that highlight Gr91's dominance:

Practical Applications: When to Choose Gr91 vs. Gr22

Choose A387 Gr91 If:

Equipment operates at 550°C+ (e.g., steam methane reformers, superheaters, high-temperature heat exchangers for hydrogen production).

Design requires a 10+ year lifespan under continuous high temp/pressure (creep is a primary failure mode).

Project follows ASME Section VIII (pressure vessels) or ASME Section I (boilers)-Gr91 is fully certified for these standards.

Applications include power generation (coal/gas-fired plants), petrochemical cracking, or thermal processing with aggressive creep conditions.

Choose SA387 Gr22 If:

Operating temperature is ≤550°C (e.g., moderate-temperature heat exchangers, hydrotreaters, low-pressure hydrogen service).

Cost efficiency is a priority (Gr22 is 20–30% more economical than Gr91).

Creep exposure is minimal (short operating cycles, intermittent high temps).

The project specifies 2.25Cr-1Mo steel for compatibility with existing systems (e.g., refineries with legacy Gr22 equipment).

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What is the difference between SA 387 Grade 11 CL 1 and Class 2?

The difference between SA 387 Grade 11 Class 1 and Class 2 Plate lies in their mechanical properties. However, they both have the same chemical composition. The tensile strength and yield strength of class 2 material is higher than that of class 1, whereas the elongation for class 1 is higher compared to class 2.

What is the ASTM A387 Grade 22 equivalent to?

Among the ASTM A387 Grade 22 equivalent steel grades, SA387 Grade 22, 10CrMo9-10 is more popular than other equivalents. SA387 Grade 22 steel is under ASME SA387/ SA387M standard. The chemical performance and technical requirements of SA387 Grade 22 steel is almost same with ASTM A387 Grade 22 steel.

What is the difference between SA 516 GR 70 and SA 387 GR 11?

Compared to carbon steel plates, SA 387 Gr 11 plates offer superior corrosion and oxidation resistance while maintaining good tensile and yield strength. Compared to SA 516 Gr 70 plates, SA 387 Gr 11 plates have better resistance to oxidation and corrosion, making them a better choice for high-temperature environments.

What is GR 91 material?

Grade 91 steel is defined as a creep strength-enhanced ferritic steel, originally developed for heat transfer tubes in fast breeder reactors, with specific modifications in chemical composition and allowable stresses based on field experience, particularly for use in fossil plants and Generation IV nuclear applications

What is the difference between A182 and A387?

Both ASTM A182 grade F11 class 2 and ASTM A387 grade 22 steel are iron alloys. They have a very high 99% of their average alloy composition in common. There are 32 material properties with values for both materials. Properties with values for just one material (1, in this case) are not shown.

GNEE Steel also supplies a variety of boilers and pressure vessel steel plates, such as A204 Grade B,A515 Grade 70,A537 Class 1,SA387 Grade 11 Class 1,P265GH,S537 Class 2,P355Q,P275N,P355N,P690Q,Q345R, etc. If you want to know more about other types of steel plates, you can call the consultation hotline at +8615824687445 or send an email to alloy@gneesteelgroup.com. You are welcome to consult us, and we are very willing to answer your questions.