What is the difference between A387 Grade 5 and A36?

A387 Grade 5 and A36 are two widely used industrial steels, but they differ fundamentally in alloy composition, performance limits, and application scope. A387 Grade 5 is a 0.5Cr-0.5Mo low-alloy steel engineered for high-temperature/pressure service, while A36 is a plain carbon steel designed for general structural and low-stress applications. Understanding their differences is critical for avoiding equipment failure, optimizing cost, and ensuring compliance-especially for critical systems like tube shell heat exchangers.

As a leading supplier of industrial steel plates and custom tube shell heat exchangers, GNEE breaks down the core distinctions between A387 Grade 5 and A36 below.

Core Differences Summary Table

Key Differences

Alloy Composition: Low-Alloy vs. Plain Carbon Steel

The most fundamental difference is their chemical makeup-this defines their performance in harsh environments:

A387 Grade 5: Contains chromium (0.30–0.80%) and molybdenum (0.40–0.65%), two alloying elements that enable high-temperature stability and corrosion resistance. These additives form stable microstructures that resist creep (slow deformation) and oxidation at elevated temps.

A36: A plain carbon steel with no intentional alloying (only trace elements). Its composition is optimized for weldability and general structural strength but lacks the additives needed for harsh service.

Mechanical Properties: Strength vs. Specialized Performance

While A36 has a similar base yield strength (250 MPa) to A387 Grade 5 Class 1 (240 MPa), the low-alloy grade outperforms in specialized conditions:

Creep Resistance: A387 Grade 5 retains 70% of its room-temperature strength at 500°C, while A36 retains only 30%. This makes A387 Grade 5 ideal for equipment under long-term heat/stress (e.g., tube shell heat exchanger shells).

Toughness at High Temps: A387 Grade 5 maintains ductility at 500°C, preventing brittle fracture. A36 becomes brittle above 450°C.

Class 2 Advantage: A387 Grade 5 Class 2 (Q&T heat treatment) offers a significantly higher yield strength (310 MPa) than A36, making it suitable for high-pressure critical equipment (e.g., hydrotreating reactors).

Applications: Matching Steel to Purpose

The differences in performance directly translate to distinct use cases:

When to Use A387 Grade 5:

High-temperature/pressure equipment (400–538°C, 10–25 MPa) like tube shell heat exchangers, petrochemical reactors, and boiler superheaters.

Sour service environments (H₂S-containing fluids) or hydrogen-rich media.

Critical equipment where failure risks safety, downtime, or environmental damage.

GNEE's custom tube shell heat exchangers use A387 Grade 5 for refineries and power plants, delivering reliable performance in harsh conditions.

When to Use A36:

General structural components (building beams, frames, supports).

Low-pressure storage tanks (atmospheric or ≤5 MPa) for non-corrosive fluids (e.g., water, dry gases).

Non-critical piping (≤400°C) and mechanical parts (brackets, flanges for low-stress use).

Cost-sensitive projects where high-temperature or corrosion resistance is not required.

Heat Treatment & Certification

A387 Grade 5: Requires controlled heat treatment (normalized + tempered for Class 1; quenched + tempered for Class 2) to achieve its high-temperature properties. Certified to ASTM A387/ASME SA-387 for pressure vessel service.

A36: Typically supplied in hot-rolled, annealed, or normalized condition (no specialized heat treatment). Certified to ASTM A36 for structural use-not approved for ASME pressure vessels or high-temperature equipment.

GNEE's Solutions for Your Application

At GNEE, we supply both ASTM-certified A387 Grade 5 (Class 1/2) and A36 steel plates, tailored to your project's needs:

A387 Grade 5: For tube shell heat exchangers, petrochemical reactors, and high-temperature/pressure equipment-available in custom thicknesses (6mm–200mm) with NACE MR0175 certification and ultrasonic testing (UT).

A36: For structural components, low-pressure tanks, and non-critical parts-offered in standard sizes with fast delivery.

One-Stop Fabrication: We integrate A387 Grade 5 into custom tube shell heat exchangers, ensuring compliance with ASME standards and optimal performance in harsh industrial environments.

Conclusion

A387 Grade 5 and A36 are designed for entirely different industrial needs:

A387 Grade 5: A high-performance low-alloy steel for high-temperature, high-pressure, and corrosive environments-critical for equipment like tube shell heat exchangers and petrochemical reactors.

A36: An economic plain carbon steel for general structural use and low-stress, low-temperature applications.

Choosing the wrong grade can lead to catastrophic failure, costly downtime, or unnecessary expenses. For example, using A36 in a tube shell heat exchanger operating at 480°C will result in creep deformation and leaks within 2–3 years.

If you're unsure which grade fits your project-whether for a tube shell heat exchanger, pressure vessel, or structural component-contact GNEE's engineering team. We provide free technical consultation to match you with the right material, ensure compliance, and optimize cost.

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Get in touch with GNEE today to discuss your A387 Grade 5 or A36 requirements and secure high-quality steel plates for your industrial project!

What is the difference between A36 and Grade 5?

Grade 5 Titanium. ASTM A36 carbon steel belongs to the iron alloys classification, while grade 5 titanium belongs to the titanium alloys. There are 30 material properties with values for both materials.

What is the difference between A36 and S235?

A36 steel has a slightly higher yield strength (250 MPa) compared to S235 steel (235 MPa). In projects where the design is based on the yield strength of A36, direct substitution with S235 may not be appropriate without re-evaluation of the structural calculations.

What material is SA 387 GR 11 Cl 2?

11 CL. 2 Plate is a pressure vessel grade steel plate that is used in high-temperature applications. It is made of a chrome-moly alloy that contains molybdenum and chromium.

What is ASTM A387 Grade 11 equivalent to?

ASME SA387 grade 11

ASTM A387 grade 11 equivalent steel is ASME SA387 grade 11. ASTM A387 grade 11 covers A387 grade 11 class 1 and A387 grade 11 class 2, which are equivalent to ASME SA387 grade 11 class 1 and SA387 grade 11 class 2 respectively.

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.