Introduction
ASTM
A841 / A841M is the standard specification for alloy steel plates produced by
the thermo-mechanical control process (TMCP) for use in welded pressure
vessels. These plates are designed to provide an excellent combination of high
strength, outstanding toughness, superior weldability, and improved resistance
to brittle fracture without requiring conventional heat treatment. ASTM A841
plates are widely used in pressure vessels, storage tanks, offshore structures,
petrochemical plants, power generation facilities, and heavy industrial
equipment operating under demanding conditions.
What
is ASTM A841 / A841M?
ASTM
A841 / A841M covers thermo-mechanically processed alloy steel plates intended
primarily for welded pressure vessels. The TMCP manufacturing process refines
the grain structure, resulting in enhanced mechanical properties, excellent
impact toughness, and improved weldability while maintaining high strength.
These
plates are widely selected for applications requiring reliable performance
under pressure and low-temperature service.
ASTM
A841 / A841M Grades
ASTM
A841 / A841M pressure vessel plates are available in the following grades:
- Grade
A (Class 1)
- Grade
B (Class 2)
- Grade
C (Class 3)
- Grade
D (Class 4)
- Grade
E (Class 5)
- Grade
E (Class 6)
- Grade
F (Class 7)
- Grade
F (Class 8)
Each grade and class is designed to
provide specific combinations of strength, toughness, and weldability to meet
the requirements of pressure vessel fabrication for various operating
temperatures and pressure conditions.
Chemical
Composition
|
Element |
Grade A |
Grade B |
Grade C |
Grade D |
Grade E |
Grade F |
|
Carbon,
Max % |
0.20 |
0.15 |
0.10 |
0.09 |
0.07 |
0.10A |
|
Manganese,
% (t ≤ 1.5 in. [40 mm]) |
0.70–1.35B |
0.70–1.35B |
0.70–1.60 |
1.00–2.00 |
0.70–1.60 |
1.10–1.70A |
|
Manganese,
% (t > 1.5 in. [40 mm]) |
1.00–1.60 |
1.00–1.60 |
1.00–1.60 |
C |
C |
C |
|
Phosphorus,
Max % |
0.030 |
0.030 |
0.030 |
0.010 |
0.015 |
0.020 |
|
Sulfur,
Max % |
0.030 |
0.025 |
0.015 |
0.005 |
0.005 |
0.008 |
|
Silicon, % |
0.15–0.50 |
0.15–0.50 |
0.15–0.50 |
0.05–0.25 |
0.05–0.30 |
0.10–0.45 |
|
Copper,
Max % |
0.35 |
0.35 |
0.35 |
0.50 |
0.35 |
0.40 |
|
Nickel,
Max % |
0.25 |
0.60 |
0.25 |
1.0–5.0 |
0.60 |
0.85 |
|
Chromium,
Max % |
0.25 |
0.25 |
0.25 |
0.30 |
0.30 |
0.30 |
|
Molybdenum,
Max % |
0.08 |
0.30 |
0.08 |
0.40 |
0.30 |
0.50 |
|
Columbium,
Max % |
0.03 |
0.03 |
0.06 |
0.05 |
0.08 |
0.10 |
|
Vanadium,
Max % |
0.06 |
0.06 |
0.06 |
0.02 |
0.06 |
0.09 |
|
Titanium,
% |
D |
D |
0.006–0.02 |
0.006–0.03 |
D |
E |
|
Boron, Max
% |
— |
— |
— |
0.0005–0.002 |
0.0007 Max |
0.0007 Max |
|
Aluminum,
Min % |
0.020
Total or 0.015 Acid SolubleD |
0.020
Total or 0.015 Acid SolubleD |
— |
— |
0.020
Total or 0.015 Acid SolubleD |
0.020
Total or 0.015 Acid SolubleE |
Notes:
- A: For each reduction of 0.01 percentage point below the
specified maximum carbon content, an increase of 0.06 percentage point above the specified maximum manganese
is permitted, up to a maximum of 1.85%.
- B: Manganese may exceed 1.35% (heat analysis) up to 1.60%, provided the carbon
equivalent (CE) does not exceed 0.47%,
or the value specified in Supplementary Requirement S77.
CE = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15 - C: Not applicable.
- D: By agreement, the steel may be
produced with titanium instead of the minimum aluminum requirement.
Titanium (heat analysis) shall be 0.006–0.02%,
and the actual titanium content shall be reported.
- E: By agreement, the steel may be
produced with titanium instead of the minimum aluminum requirement.
Titanium (heat analysis) shall be 0.006–0.03%,
and the actual titanium content shall be reported.
Tensile
Requirements
|
Property |
Grade A (Class 1) |
Grade B (Class 2) |
Grade C (Class 3) |
Grade D (Class 4) |
Grade E (Class 5) |
Grade E (Class 6) |
Grade F (Class 7) |
Grade F (Class 8) |
|
Yield
Strength, Min, ksi [MPa] (to 1.5
in. [40 mm] incl.) |
50 [345] |
60 [415] |
100 [690] |
70 [485] |
75 [515] |
70 [485] |
75 [515] |
80 [550] |
|
Yield
Strength, Min, ksi [MPa] (over 1.5
to 2.5 in. [40–65 mm]) |
50 [345] |
60 [415] |
A |
A |
A |
A |
A |
A |
|
Yield
Strength, Min, ksi [MPa] (over 2.5
in. [65 mm]) |
45 [310] |
55 [380] |
A |
A |
A |
A |
A |
A |
|
Tensile
Strength, ksi [MPa] (to 1.5 in. [40 mm] incl.) |
70–90
[480–620] |
80–100
[550–690] |
145–170
[1000–1170] |
84–104
[580–715] |
88–108
[605–745] |
82–102
[565–705] |
86–106
[590–730] |
90–110
[620–760] |
|
Tensile
Strength, ksi [MPa] (over 1.5 to 2.5 in. [40–65 mm]) |
70–90
[480–620] |
80–100
[550–690] |
A |
A |
A |
A |
A |
A |
|
Tensile
Strength, ksi [MPa] (over 2.5 in. [65 mm]) |
65–85
[450–585] |
75–95
[515–655] |
A |
A |
A |
A |
A |
A |
|
Elongation
in 2 in. [50 mm], Min % (to 1.5
in. [40 mm] incl.) |
22 |
22 |
13 |
20 |
19 |
20 |
19 |
18 |
|
Elongation
in 2 in. [50 mm], Min % (over 1.5
to 2.5 in. [40–65 mm]) |
22 |
22 |
A |
A |
A |
A |
A |
A |
|
Elongation
in 2 in. [50 mm], Min % (over 2.5
in. [65 mm]) |
22 |
22 |
A |
A |
A |
A |
A |
A |
|
Elongation
in 8 in. [200 mm], Min % (to 1.5
in. [40 mm] incl.) |
18 |
— |
— |
16 |
15 |
16 |
15 |
14 |
|
Elongation
in 8 in. [200 mm], Min % (over 1.5
to 2.5 in. [40–65 mm]) |
18 |
— |
A |
A |
A |
A |
A |
A |
|
Elongation
in 8 in. [200 mm], Min % (over 2.5
in. [65 mm]) |
18 |
— |
A |
A |
A |
A |
A |
A |
Notes:
- A: Not applicable.
- B: See ASTM A20/A20M for
elongation requirement adjustments.
Supply Condition
ASTM
A841 / A841M plates are commonly supplied in the following conditions:
- Hot
rolled
- Normalized
- Quenched
and tempered
- Annealed
- Stress
relieved
- Fabrication-ready
condition
Surface Finish
ASTM
A841 / A841M plates are available with the following surface finishes:
- Mill
finish
- Shot
blasted finish
- Pickled
finish
- Ground
finish
- Machined
finish (when specified)
Standard Sizes
Plates
- Thickness:
6 mm to 200 mm
- Width:
1000 mm to 3500 mm
- Length:
Up to 12000 mm
Custom
dimensions, flame-cut components, and machined plates are available according
to customer requirements.
Manufacturing Process
The
manufacturing process generally includes:
- Steel
melting
- Continuous
casting
- Thermo-Mechanical
Controlled Processing (TMCP)
- Plate
rolling
- Controlled
cooling
- Plate
leveling
- Cutting
- Surface
inspection
- Dimensional
inspection
- Final
quality testing
Key
Properties
ASTM
A841 / A841M plates offer numerous performance advantages, including:
- High
strength
- Excellent
weldability
- Superior
impact toughness
- Excellent
low-temperature toughness
- Outstanding
fatigue resistance
- Good
corrosion resistance
- Excellent
dimensional stability
- High
structural integrity
- Long
service life
- Reliable
performance in pressure applications
Advantages
ASTM
A841 / A841M pressure vessel plates provide several benefits, including:
- Excellent
strength-to-weight ratio
- Outstanding
weldability without extensive heat treatment
- High
toughness
- Improved
fabrication characteristics
- Excellent
resistance to brittle fracture
- Long
service life
- Reduced
fabrication costs
- Reliable
performance under pressure
- Low
maintenance requirements
- Suitable
for demanding industrial applications
Available
Forms
ASTM
A841 / A841M products are commonly supplied as:
- Pressure
Vessel Plates
- Heavy
Steel Plates
- Boiler
Plates
- Structural
Plates
- Cut-to-Size
Plates
- Flame-Cut
Components
- Machined
Plates
- Custom
Fabricated Plates
Applications
Pressure Vessels
Used
for manufacturing welded pressure vessels operating under high pressure and
varying temperatures.
Boilers
Suitable
for boiler drums, steam generators, and auxiliary boiler equipment.
Petrochemical Industry
Applied
in reactors, separators, pressure drums, and process vessels.
Oil and Gas Industry
Used
for pressure equipment, storage vessels, and processing facilities.
Power Generation
Suitable
for boilers, heat recovery systems, condensers, and pressure-containing
equipment.
Chemical Processing Plants
Used
in pressure vessels handling corrosive chemicals and industrial process fluids.
Offshore Industry
Applied
in offshore platforms, process modules, and marine pressure equipment.
Storage Tanks
Suitable
for heavy-duty storage tanks and process tanks.
Refineries
Used
in refinery processing units and high-pressure equipment.
Heavy Engineering
Applied
in the fabrication of industrial equipment requiring high-strength pressure
vessel steel.
Quality
Testing
ASTM
A841 / A841M plates undergo comprehensive testing, including:
- Chemical
composition analysis
- Tensile
testing
- Yield
strength testing
- Elongation
testing
- Charpy
impact testing
- Ultrasonic
testing
- Hardness
testing
- Dimensional
inspection
- Surface
quality inspection
- Material
certification
Factors
to Consider When Selecting ASTM A841 / A841M Plates
Several
factors should be evaluated before selecting ASTM A841 / A841M plates:
- Grade
and class selection
- Operating
pressure
- Service
temperature
- Plate
thickness
- Weldability
requirements
- Impact
toughness requirements
- Fabrication
method
- Applicable
design codes
- Corrosive
environment
- Inspection
requirements
Why
Choose ASTM A841 / A841M Pressure Vessel Plates?
ASTM
A841 / A841M plates are preferred because they combine high strength, excellent
toughness, superior weldability, and reliable performance achieved through the
thermo-mechanical control process. Their ability to perform under demanding
pressure and low-temperature conditions makes them an excellent choice for
pressure vessels, boilers, offshore structures, and heavy industrial equipment.
Conclusion
ASTM A841 / A841M Pressure Vessel
Steel Plates are engineered to deliver outstanding mechanical performance,
excellent weldability, and superior toughness for critical pressure vessel
applications. Their combination of high strength, reliability, and fabrication
efficiency makes ASTM A841 / A841M one of the preferred materials for modern
pressure vessel construction.
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