ASTM A672 / ASME SA-672 covers steel pipe that is electric-fusion-welded with filler metal added, fabricated from pressure-vessel-quality plate, and intended for high-pressure service at moderate temperatures. On this page the grade is C60 and the classes are 12, 22 and 32. The grade and the class are two different pieces of information: the grade names the plate, and the class names the heat treatment and the examination package applied to the finished pipe.
Grade C60 belongs to the C series of A672, which is built on ASTM A516 plate. The numeric part, 60, is the minimum tensile strength of the plate in ksi (60 ksi, equivalent to 415–550 MPa). Class 12, 22 and 32 all keep the same C60 chemistry and the same strength level; what changes between them is the thermal condition of the pipe body and, with it, the residual stress state and grain structure. All three of these classes also include radiographic examination of the weld and a hydrostatic pressure test, which is why the second digit of the class number matters as much as the first.
A672 pipe is a welded, plate-based product. It is not seamless pipe, and it is not an API 5L / ISO 3183 line pipe specification, although the same forming lines are often used for both. It exists to cover large diameters and heavy walls that are uneconomic or impossible to produce as seamless tube: the specification nominally starts at 16 in [400 mm] outside diameter and runs to a wall thickness of 3 in [75 mm] inclusive, with other dimensions available by agreement provided all other requirements are still met.
Standard Scope, Edition and Designation
The active edition is ASTM A672/A672M-19(2025), titled Standard Specification for Electric-Fusion-Welded Steel Pipe for High-Pressure Service at Moderate Temperatures. The corresponding ASME boiler and pressure vessel material designation is SA-672. The specification covers pipe electric-fusion-welded with filler metal added, fabricated from pressure-vessel-quality plate of several analyses and strength levels. Heat treatment may or may not be required to attain the desired properties or to comply with the applicable code, and supplementary requirements are provided for use when additional testing or examination is desired.
Section 1.2 nominally covers pipe 16 in [400 mm] in outside diameter or larger with wall thicknesses up to 3 in [75 mm], inclusive. Pipe having other dimensions may be furnished provided it complies with all other requirements of the specification. Section 1.3 states that the grade designates the type of plate used, while the class designates the type of heat treatment performed during manufacture, whether the weld is radiographically examined, and whether the pipe has been pressure tested.
| Element | Governing wording | What to put on the enquiry |
|---|---|---|
| Standard title | Electric-Fusion-Welded Steel Pipe for High-Pressure Service at Moderate Temperatures | ASTM A672/A672M (or ASME SA-672 if the code requires it) |
| Edition | Active edition A672/A672M-19(2025); the edition named in the purchase order or project specification governs | State the edition and the unit system explicitly |
| Units | SI and inch-pound values are regarded separately; inch-pound units apply unless the "M" designation is specified in the order | Specify "M" if SI is the controlling system |
| Grade | Designates the type of plate used (C60 = A516 Grade 60 plate series) | Grade C60 |
| Class | Designates heat treatment, radiography and pressure test (Section 1.3.3) | Class 12, 22 or 32 - one class per line item |
| Dimensions | OD 16 in [400 mm] and larger; wall up to 3 in [75 mm] inclusive | OD × wall, length, quantity, tolerances |
Class 12, 22 and 32 in the ASTM Class Designations
The class table in Section 1.3.3 is the single most useful lookup on this page. The first digit identifies the heat treatment on the pipe; the second digit identifies whether radiographic examination and the hydrostatic pressure test are required. The three classes named in the product title sit in the middle of the table: all have radiography under Section 9 and the pressure test under Section 8.3, and they differ only in heat treatment.
| Class | Heat treatment on pipe | Radiography (Sect. 9) | Pressure test (Sect. 8.3) |
|---|---|---|---|
| 10 | None | Not required | Not required |
| 11 | None | Required | Not required |
| 12 | None | Required | Required |
| 13 | None | Not required | Required |
| 20 | Stress relieved | Not required | Not required |
| 21 | Stress relieved | Required | Not required |
| 22 | Stress relieved | Required | Required |
| 23 | Stress relieved | Not required | Required |
| 30 | Normalized | Not required | Not required |
| 31 | Normalized | Required | Not required |
| 32 | Normalized | Required | Required |
| 33 | Normalized | Not required | Required |
| 40 | Normalized and tempered | Not required | Not required |
| 41 | Normalized and tempered | Required | Not required |
| 42 | Normalized and tempered | Required | Required |
| 43 | Normalized and tempered | Not required | Required |
| 50 | Quenched and tempered | Not required | Not required |
| 51 | Quenched and tempered | Required | Not required |
| 52 | Quenched and tempered | Required | Required |
| 53 | Quenched and tempered | Not required | Required |
Radiographic examination under Section 9 is made on the full length of each weld. Heat-treated classes are processed in temperature-controlled furnaces with recorded heat-treatment charts; the chart should be requested with the documentation package. Class 12 requires no post-weld heat treatment, Class 22 requires stress relieving to Section 5.3.1, and Class 32 requires normalizing to Section 5.3.2.
Technical Clarifications on the Retained Text
The table below is the line-by-line comparison between the wording retained from the original page and the governing wording of ASTM A672/A672M. It is provided so a buyer reading the original description is not left with a specification that would be rejected at technical bid evaluation.
| # | Retained original wording | Governing wording / correction | Why it matters |
|---|---|---|---|
| 1 | "high pressure service at atmospheric and lower temperatures" | A672 is for moderate temperatures. "Atmospheric and lower temperatures" is the title of ASTM A671. | Two different service envelopes; a low-temperature enquiry should be quoted against A671. |
| 2 | "mainly include CL12, CL22 and CL32 grades" | CL12/CL22/CL32 are classes. The grade is C60. | Grade and class are separate fields on the purchase order and on the MTC. |
| 3 | "16 inches (405 mm) outer diameter" | 405 mm is the inch-pound conversion used in A672-96; the current A672M wording is 16 in [400 mm] OD or larger. | Prevents a buyer from reading 405 mm as a fixed or maximum size. |
| 4 | "¼ inch (6.4 mm) wall thickness" | A wall of ¼ in [6.4 mm] or greater is the A671 lower bound. A672 sets an upper bound of 3 in [75 mm] inclusive. | Reverses the dimensional logic of the specification and changes the RFQ. |
| 5 | "Up to 250 mm Thickness" | Outside the nominal A672 scope. Other dimensions may be furnished only if all other requirements are still met. | A 250 mm wall would need explicit agreement and re-verification of the whole order. |
| 6 | "As Rolled, Normalizing Rolled, Thermomechanical Rolled / Formed ... BR / N / Q / T" | These are plate-mill / line-pipe delivery-condition codes. A672 classes are: none, stress relieved, normalized, normalized and tempered, quenched and tempered. | Quoting a delivery-condition code instead of a class leaves the heat treatment undefined. |
| 7 | "16" NB To 100" NB (Nominal Bore Size)" | A672 pipe is dimensioned by outside diameter. NB/NPS is an ASME B36.10 sizing system. | Large-diameter EFW is ordered by OD × wall, not by nominal bore. |
| 8 | "Schedule 20 To Schedule XXS" | Schedule designations belong to standard NPS sizes; custom large-diameter walls are stated in mm or inches. | Avoids ambiguity when the schedule does not map to the required wall. |
Chemical Composition of Grade C60
A672 derives its chemical requirements from the plate specification named by the grade. For C60 that is ASTM A516/A516M Grade 60. Carbon limits are thickness dependent, and manganese limits change at 1/2 in [12.5 mm]. The values below are the heat-analysis limits commonly tabulated for Grade 60 plate; the controlling figures are those of the plate edition named in the order and must be confirmed against the mill certificate.
| Element | Thickness condition | Limit |
|---|---|---|
| Carbon (C) | 1/2 in [12.5 mm] and under | 0.21 max |
| Carbon (C) | Over 1/2 in to 2 in [12.5 to 50 mm] incl. | 0.23 max |
| Carbon (C) | Over 2 in to 4 in [50 to 100 mm] incl. | 0.25 max |
| Carbon (C) | Over 4 in to 8 in [100 to 200 mm] incl. | 0.27 max |
| Carbon (C) | Over 8 in [200 mm] | 0.27 max |
| Manganese (Mn) | 1/2 in [12.5 mm] and under | 0.55–0.98 (0.79–1.30 permitted for Grade 60 plate in this range) |
| Manganese (Mn) | Over 1/2 in [12.5 mm] | 0.79–1.30 |
| Phosphorus (P) | All | 0.025 max |
| Sulfur (S) | All | 0.025 max |
| Silicon (Si) | All | 0.13–0.45 |
For each reduction of 0.01 percentage point below the specified carbon maximum, an increase of 0.06 percentage point above the specified manganese maximum is permitted, up to a maximum of 1.60 %. In addition to the plate analysis, A672 requires an analysis of each mill heat of plate material and an analysis of the finished deposited weld material from each 500 ft [150 m] or fraction thereof. That weld-metal analysis is specific to EFW pipe and is one of the checks a buyer should ask to see on the certificate package.
Mechanical Properties and Test Lot
The mechanical properties of C60 pipe follow A516 Grade 60 plate. One tension test specimen represents each lot of finished pipe, and one transverse guided-weld bend test (two specimens) represents each lot. Elongation is measured on both the 8 in [200 mm] and the 2 in [50 mm] gauge length, so the two figures should not be used interchangeably.
| Property | Requirement | Reference basis |
|---|---|---|
| Tensile strength | 60–80 ksi [415–550 MPa] | A516 Grade 60 plate, as referenced by A672 |
| Yield strength, minimum | 32 ksi [220 MPa] | A516 Grade 60 plate |
| Elongation in 8 in [200 mm], minimum | 21 % | Plate tensile test |
| Elongation in 2 in [50 mm], minimum | 25 % | Plate tensile test |
| Tension test | One specimen per lot of finished pipe | A672 mechanical test requirements |
| Transverse guided-weld bend test | Two specimens per lot of finished pipe | A672 mechanical test requirements |
Class does not change strength. Class 12, 22 and 32 do not raise the tensile or yield figures. Heat treatment changes the stress state and microstructure of the pipe; the specified strength remains that of the C60 plate. A request for higher strength should be handled by changing the grade (C65 or C70), not by changing the class.
Class 12 vs Class 22 vs Class 32: Selection
All three classes in the product title share the same radiography and pressure-test package. The decision between them is a heat-treatment decision driven by the design code, the design temperature, the weld residual stress and the required microstructure. The table below is a selection aid, not a substitute for the project piping code.
| Class | Heat treatment on pipe | What it changes | Examination package | State on the order |
|---|---|---|---|---|
| Class 12 | None (as welded) | No post-weld thermal cycle; the weld and HAZ keep the as-welded condition | Radiography (Sect. 9) + pressure test (Sect. 8.3) | Class 12, no PWHT |
| Class 22 | Stress relieved (Sect. 5.3.1) | Reduces welding residual stresses in the pipe body and weld region | Radiography (Sect. 9) + pressure test (Sect. 8.3) | Class 22, stress-relief chart required |
| Class 32 | Normalized (Sect. 5.3.2) | Refines and homogenises the grain structure of the pipe body | Radiography (Sect. 9) + pressure test (Sect. 8.3) | Class 32, normalizing chart required |
Class 22 is frequently specified where the design code calls for post-weld heat treatment or where residual stress is a documented concern. Class 32 is selected when normalizing is required by the construction code or by the purchaser's material specification, for example where uniform microstructure across the pipe body is a stated requirement. Class 12 is used where no heat treatment is required and the as-welded condition is acceptable to the design code. In every case the heat-treatment chart, radiography reports and hydrostatic test record should be listed as deliverables on the purchase order.
Dimensions, Tolerances and End Finish
Dimensional requirements come from the governing edition and from the project specification. A672 nominally starts at 16 in [400 mm] OD and tops out at 3 in [75 mm] wall; sizes outside these limits can be furnished if all other requirements of the specification are still satisfied. Because large-diameter EFW pipe is normally made to order, the OD, wall, length and end preparation should be specified as explicit values rather than by a schedule designation alone.
| Item | Reference / typical range | What the buyer should fix |
|---|---|---|
| Outside diameter | 16 in [400 mm] and larger nominally; larger diameters by agreement | OD in mm or inches, plus OD tolerance |
| Wall thickness | Up to 3 in [75 mm] inclusive nominally | Nominal wall, minus tolerance, and any corrosion allowance |
| Length | Single random, double random or fixed length to project requirement | Fixed length, random range and permitted shorts |
| Sizing reference | ASME B36.10 where NPS/schedule dimensions are used | Confirm whether OD × wall or NPS × schedule governs |
| Ends | Plain ends, bevelled ends, threaded ends or coupling as originally listed | Bevel angle, root face, root gap; end protection |
| Dimensional tolerance | To the governing edition of A672 and the project specification | OD, wall, out-of-roundness, straightness, length tolerance |
| Packing | Loose, bundle, wooden pallet/box, plastic wraps, end caps, bevel protectors (as originally listed) | Export packing, marking, lifting points, protection for coated ends |
ASTM A671 vs ASTM A672
A671 and A672 are companion EFW specifications written by the same subcommittee. They use similar welding, heat-treatment and dimensional concepts, but they are aimed at opposite ends of the temperature scale. The original description on this page uses the A671 service-temperature wording, so the distinction is set out here explicitly.
| Point | ASTM A671 / A671M | ASTM A672 / A672M |
|---|---|---|
| Standard title | Electric-Fusion-Welded Steel Pipe for Atmospheric and Lower Temperatures | Electric-Fusion-Welded Steel Pipe for High-Pressure Service at Moderate Temperatures |
| Service envelope | Atmospheric and lower temperatures; low-temperature toughness is central | High-pressure service at moderate temperatures |
| Dimensional scope | OD 16 in [400 mm] and larger; wall ¼ in [6.4 mm] and greater | OD 16 in [400 mm] and larger; wall up to 3 in [75 mm] inclusive |
| Impact testing | Built into the grade/class system with mandatory Charpy V-notch testing of weld and HAZ at the specified temperature | Not mandatory by default; additional testing is invoked through supplementary requirements on the order |
| Typical grade names | CC60, CC65, CC70 and low-temperature alloy grades | B60, B65, B70, C60, C65, C70 |
| ASME counterpart | SA-671 | SA-672 |
If the line operates at low ambient temperature or the design code calls for a guaranteed impact value, an A672 C60 order without a supplementary impact requirement is not equivalent to an A671 order. The test temperature, specimen location (base metal, weld, HAZ) and acceptance criteria must be written into the enquiry and the ITP.
Heat Treatment, NDT and Pressure Testing by Class
For the three classes on this page the examination package is identical: radiographic examination under Section 9 and a hydrostatic pressure test under Section 8.3. The difference is the thermal cycle. The table below maps the required checks so that an inspection and test plan can be written directly from it.
| Operation | Class 12 | Class 22 | Class 32 | Reference |
|---|---|---|---|---|
| No post-weld heat treatment | Required condition | Not applicable | Not applicable | Sect. 1.3.3 |
| Stress relieving | Not applicable | Required | Not applicable | Sect. 5.3.1 |
| Normalizing | Not applicable | Not applicable | Required | Sect. 5.3.2 |
| Radiography, full length of each weld | Required | Required | Required | Sect. 9 |
| Hydrostatic pressure test | Required | Required | Required | Sect. 8.3 |
| Tension test, one per lot | Required | Required | Required | Mechanical test requirements |
| Transverse guided-weld bend, two per lot | Required | Required | Required | Mechanical test requirements |
| Plate heat analysis + weld metal analysis each 500 ft | Required | Required | Required | Material analysis requirements |
Supplementary requirements are available where additional testing or examination is desired. Impact testing is the one that most often needs to be named explicitly: A672 is written for moderate-temperature service, so a Charpy V-notch requirement, test temperature and acceptance criteria must be stated on the order if the design involves low ambient or low operating temperatures. Ultrasonic examination, additional NDT after hydrotest and third-party witness points should be listed in the ITP in the same way.
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What does "Class 12, 22, 32" mean on an ASTM A672 C60 pipe?
Class is not a strength level. Under ASTM A672 Section 1.3.3 the class designates the heat treatment performed during manufacture, whether the weld is radiographically examined, and whether the pipe has been pressure tested. C60 is the grade and names the A516 Grade 60 plate; 12, 22 and 32 are three class conditions of that same material.
What is the difference between Class 12, Class 22 and Class 32?
Class 12 is supplied as welded with no post-weld heat treatment, Class 22 is stress relieved under Section 5.3.1, and Class 32 is normalized under Section 5.3.2. All three include radiographic examination of the weld under Section 9 and the hydrostatic pressure test under Section 8.3. The chemistry and the 415-550 MPa tensile / 220 MPa minimum yield requirements are identical.
Is ASTM A672 the same as ASTM A671?
No. A671 is written for atmospheric and lower temperatures and builds mandatory Charpy V-notch testing into its grade and class system. A672 is written for high-pressure service at moderate temperatures, where impact testing is invoked through supplementary requirements when the purchaser needs it. A671 also sets a minimum wall of 1/4 in [6.4 mm], while A672 sets a maximum wall of 3 in [75 mm].
Which plate is used for A672 Grade C60?
The C series uses ASTM A516 pressure-vessel plate, so C60 is built on A516 Grade 60. That plate carries a tensile strength of 60-80 ksi [415-550 MPa], a minimum yield of 32 ksi [220 MPa] and elongation of 21% in 200 mm or 25% in 50 mm. The governing values are those of the plate edition named in the purchase order and should be checked against the mill certificate.
What is the largest wall thickness covered by ASTM A672?
The specification nominally covers 16 in [400 mm] outside diameter or larger with wall thickness up to 3 in [75 mm] inclusive. Pipe with other dimensions may be furnished provided it still complies with all other requirements of the specification, so any size outside that range needs to be agreed explicitly on the order rather than assumed.
Does Class 22 require radiography and a hydrostatic test?
Yes. Class 22 is stress relieved and carries both radiography under Section 9 and the pressure test under Section 8.3. Radiographic examination is made on the full length of each weld. Note that the neighbouring classes are not equivalent: Class 21 omits the pressure test and Class 23 omits radiography.
Can A672 C60 be used for low-temperature service?
Not as a default. A672 is a moderate-temperature specification and impact testing is not mandatory unless supplementary requirements are named on the order. If the design involves low ambient or low operating temperatures, either order against ASTM A671 or specify the Charpy test temperature, specimen locations in base metal, weld and HAZ, and the acceptance criteria in the enquiry and the ITP.
What documents should be requested with an A672 C60 order?
At minimum: an EN 10204 3.1 mill certificate (3.2 where third-party witness is required), plate heat analysis and deposited weld-metal analysis, tension and transverse guided-weld bend results, radiography reports and images, the hydrostatic test record, and the heat-treatment chart for Class 22 or 32. WPS/PQR, welder qualifications, a dimensional report, marking list, ITP and packing list complete the traceability chain.
Is ASTM A672 C60 pipe seamless?
No. A672 covers electric-fusion-welded pipe made from plate with filler metal added, with a longitudinal weld that is examined over its full length. The seamless alternative for smaller diameters is a material such as ASTM A106, but a seamless product cannot be substituted for an A672 order without the purchaser's written acceptance, because the test lot and weld examination are defined around the EFW seam.
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