Overview of ASTM A671 CC60 Class 43 Pipe
ASTM A671/A671M is the specification for electric-fusion-welded steel pipe made from pressure-vessel-quality plate, intended for high-pressure service at atmospheric and lower temperatures. The pipe is formed from plate and welded with a double-sided submerged arc weld, then heat treated and examined according to the class. It is produced in large diameters, normally 16 in, about 406 mm, and larger.
The designation CC60 Class 43 has two independent parts. CC60 names the plate material and its strength level: the pipe is made from A516/A516M Grade 60 plate, a killed fine-grain carbon steel. Class 43 names the heat treatment and examination requirements applied to the finished pipe. Each part is explained below.
What the Grade Means
In the A671 designation the two-letter prefix identifies the pressure-vessel plate specification from which the pipe is made, and the number states the minimum tensile strength in ksi. The grade CC60 therefore means pipe made from A516/A516M Grade 60, with a minimum tensile strength of 60 ksi, about 415 MPa.
| Grade | Plate specification | Steel type | Minimum tensile strength |
|---|---|---|---|
| CC60 | A516/A516M Grade 60 | killed fine-grain carbon steel | 60 ksi, about 415 MPa |
CC60 is made from A516 Grade 60, a killed fine-grain carbon steel plate with improved notch toughness for moderate and lower temperature service. The plate tensile range is 60 to 80 ksi.
In terms of strength, The minimum yield strength of the plate is 32 ksi, about 220 MPa..
How the A671 Class System Works
The class is a two-digit code. The first digit selects the heat-treatment family applied to the pipe after welding.
| Class family | Heat treatment applied to the pipe |
|---|---|
| 10 to 13 | None; delivered as welded |
| 20 to 23 | Stress relieved after welding |
| 30 to 33 | Normalized |
| 40 to 43 | Normalized and tempered |
| 50 to 53 | Quenched and tempered |
| 70 to 73 | Quenched and precipitation heat treated |
The second digit selects the examination level.
| Last digit | Radiography of the weld | Pressure test |
|---|---|---|
| 0 | Not required | Not required |
| 1 | Full-length radiography of each weld per ASME VIII UW-51 | Not required |
| 2 | Full-length radiography of each weld per ASME VIII UW-51 | Required per A530/A530M |
| 3 | Not required | Required per A530/A530M |
What Class 43 Means for This Pipe
Class 43 has two digits. The first digit 4 selects the heat-treatment family, which means the pipe is normalized and then tempered after welding. The second digit 3 selects the examination level, which means no full-length radiography is required by the class, but a hydrostatic pressure test is required in accordance with A530/A530M.
Taken together, Class 43 pipe is the pipe is normalized and then tempered after welding, and no full-length radiography is required by the class, but a hydrostatic pressure test is required in accordance with A530/A530M. These requirements are fixed at the time of ordering, recorded on the order documents and confirmed on the mill test certificate.
A516 grades respond well to normalizing, so classes in the 20 to 43 range are common; classes in the quenched families should be confirmed with the mill.
Typical Applications
CC60 pipe is used for pressure vessels, storage tanks and lower temperature piping where the fine-grain A516 plate family provides better toughness than ordinary carbon steel.
Manufacturing, Testing and Documentation
A671 pipe starts as pressure-vessel-quality plate supplied under the applicable plate standard. The plate is formed into a cylinder and the longitudinal seam is welded by the submerged arc process from both the inside and the outside, producing a full-penetration weld. After welding, the pipe receives the heat treatment of the selected class and then the examination and tests required by the class and by A671/A671M.
Testing normally includes chemical analysis of the heat, tensile testing, and the radiography and hydrostatic pressure tests required by the class. Charpy V-notch impact testing is performed when the design code or the purchase order requires it, and the plate may be ultrasonically examined under A435 or a supplementary requirement. Every pipe is traceable to its plate heat number, and the mill test certificate records the chemical analysis, mechanical test results, heat treatment details and examination results.
The available outside diameters, wall thicknesses and lengths depend on the plate widths and the forming and welding capability of the producing mill, so the required OD, wall, length and end finish should be confirmed with the supplier before ordering.
FAQ
Q1. What does the grade CC60 mean in the A671 designation?
The two-letter prefix identifies the plate specification, and the number states the minimum tensile strength in ksi. CC60 means pipe made from A516/A516M Grade 60 plate, a killed fine-grain carbon steel, with a minimum tensile strength of 60 ksi, about 415 MPa.
Q2. What does Class 43 mean?
Class 43 is read in two digits: the first digit selects the heat-treatment family, the pipe is normalized and then tempered after welding, and the second digit selects the examination level, which means no full-length radiography is required by the class, but a hydrostatic pressure test is required in accordance with A530/A530M.
Q3. What is the minimum tensile strength of CC60 pipe?
60 ksi, about 415 MPa. The number in the grade name states this value directly; it is a tensile value, not a yield value. The minimum yield strength of the plate is 32 ksi, about 220 MPa.
Q4. Does Class 43 define a service temperature?
No. A class defines heat treatment and examination only, never a service temperature. The safe operating temperature is set by the plate material, the impact test requirements and the governing design code; for the CC60 grade, the steel family and its qualified toughness determine the low-temperature limit.
Q5. What tests are performed on A671 pipe?
Every heat is verified by chemical analysis and tensile testing. The class determines whether full-length radiography of the longitudinal weld and a hydrostatic pressure test are required. Charpy impact testing, ultrasonic examination of the plate and other supplementary tests are added when the design code or the purchase order specifies them, and all results are reported on the mill test certificate.
Q6. How is A671 pipe manufactured and what sizes are available?
A671 pipe is formed from pressure-vessel-quality plate and welded with a double-sided submerged arc weld, then heat treated and examined per the class. It is produced in outside diameters of 16 in, about 406 mm, and larger, with wall thicknesses selected for the design pressure and lengths typically supplied in single or double random. Exact availability depends on the producing mill and must be confirmed before ordering.
