Certified ASTM A387 Grade 11 Class 1 alloy steel plates for boilers and pressure vessels at elevated temperature service. Manufacturer supply with full inspection. Contact us for the latest price list.
ASTM A387 Grade 11 Class 1 alloy steel plates
If your project requires ASTM A387 Grade 11 Class 1 alloy steel plate for welded boilers or pressure vessels operating at elevated temperatures, GNEE is your reliable manufacturer and global supplier.
ASTM A387 Gr 11 CL 1 is a chromium-molybdenum (Cr-Mo) alloy steel plate designed to deliver stable mechanical strength, oxidation resistance, and corrosion resistance under long-term thermal service conditions.
What Is ASTM A387 Gr 11 CL 1 Alloy Steel Plate?
ASTM A387 Grade 11 Class 1 is primarily intended for:
- Welded boilers
- Pressure vessels
- Heat exchangers
- Petrochemical and refinery equipment
The steel contains approximately 1.25% chromium and 0.5% molybdenum, providing enhanced resistance to oxidation, creep, and high-temperature corrosion compared with carbon steel.
ASTM A387 Grade 11 vs Other Pressure Vessel Grades
- Most ASTM A387 grades are supplied in two tensile strength classes
- Grade 91 and Grade 911 are available only as Class 2
- ASTM A387 Gr 11 CL 1 offers balanced strength and weldability
- This makes Grade 11 Class 1 a cost-effective solution for medium-temperature pressure vessel applications.
ASTM A387 Grade 11 Class 1 Steel Dimensions
| Item | Range |
|---|---|
| Thickness | 6 mm – 300 mm |
| Width | 1500 mm – 4050 mm |
| Length | 3000 mm – 15000 mm |
Custom cutting and plate processing are available upon request.
Supplementary Technical Options for A387 Gr 11 CL 1
GNEE supports a full range of supplementary requirements to meet critical service conditions:
HIC Test
NACE MR0175 / ISO 15156
Z15 / Z25 / Z35 (Through-thickness testing)
S1 – S14, S17 (ASTM supplementary requirements)
These options ensure suitability for sour service and demanding pressure vessel environments.
Chemical Composition of ASTM A387 Grade 11 Class 1
| Element | Content (%) |
|---|---|
| Carbon (C) | 0.04 – 0.17 |
| Silicon (Si) | 0.44 – 0.86 |
| Manganese (Mn) | 0.35 – 0.73 |
| Phosphorus (P) | ≤ 0.035 |
| Sulphur (S) | ≤ 0.035 |
| Chromium (Cr) | 0.94 – 1.56 |
| Molybdenum (Mo) | 0.40 – 0.70 |
Carbon Equivalent (Ceq):
Ceq = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15 %
Mechanical Properties of ASTM A387 Gr 11 CL 1 Plate
| Thickness | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (%) |
|---|---|---|---|
| t ≤ 50 mm | ≥ 240 | 415 – 585 | ≥ 22 |
| 50 < t ≤ 200 mm | ≥ 240 | 415 – 585 | ≥ 19 |
These properties ensure safe operation under pressure and elevated temperature conditions.
Equivalent Steel Grades of ASTM A387 Gr 11 Class 1
| Region | Equivalent Grade |
|---|---|
| Europe | EN equivalent (Cr-Mo category) |
| Belgium | 621 Gr A / B |
| UK | BS 621 |
| Others | Available upon request |
Why Choose GNEE ASTM A387 Grade 11 Class 1 Plates
Manufacturer-direct supply with stable quality
Full mill test certificate (EN 10204 3.1 / 3.2)
Third-party inspection: SGS, BV, TUV, LR
Fast delivery from warehouse stock
Competitive pricing for pressure vessel projects
As a professional manufacturer, GNEE supplies certified ASTM A387 Grade 11 Class 1 alloy steel plates for boilers and pressure vessels worldwide. Our products deliver reliable performance at elevated temperatures while meeting strict petrochemical and refinery standards.
Contact us for the latest ASTM A387 Grade 11 Class 1 alloy steel plate price list and technical datasheets today.
Contact us for latest ASTM A387 Grade 11 Class 1 alloy steel plate price list
What is ASTM A387 material?
ASTM A387 GR. 91 CL. 2 Alloy Steel Plates manufactured at the world's finest steel mills, this molybdenum-chrome based alloy has excellent resistance to greater working temperatures, making it the right selection for various applications like in gas, oil, chemical, and power generation.
What is ASTM A387 Grade 11 equivalent to?
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.
What is the difference between ASTM A182 and A387?
A387 is Plate material. A182 is Forging material. You can refer relevant ASTM Book of standards.
What is ASTM A387?
The ASTM A387 specification is the Standard Specification for Pressure Vessel Plates, Alloy Steel, Chromium-Molybdenum plates used in the application of welded boilers and pressure vessels subjected to elevated temperatures. The two grades SSAB produces are available as Class 1 and/or Class 2.