Quick Answer
Quick Answer
ASTM A53 covers black and hot-dipped galvanized welded and seamless steel pipe for mechanical and pressure applications. ASTM A106 covers seamless carbon-steel pipe for high-temperature service. Both have Grade A and B (A106 also has Grade C). A106 Grade B is the most-specified carbon steel pipe for process piping; A53 includes ERW and furnace-butt-welded types, making it unsuitable for the highest temperature services where A106 dominates.
ASTM A53/A53M and ASTM A106/A106M are the two most frequently cited carbon steel pipe standards in process plant and structural applications. A53 was originally a general-purpose pipe standard covering both welded and seamless pipe; A106 was developed specifically for high-temperature pressure service requiring seamless construction. Together they cover the majority of carbon steel piping in refineries, power plants, HVAC systems, and structural hollow sections.
Scope and Applicability
ASTM A53 Scope
- Covers seamless and welded (ERW and furnace-butt-welded) black and hot-dipped galvanized steel pipe
- Sizes: NPS ⅛ through NPS 26 (OD 10.3 mm to 660 mm)
- Intended for: mechanical and pressure applications, steam, water, gas, and air services
- Types: Type F (furnace-butt-welded), Type E (electric-resistance-welded ERW), Type S (seamless)
ASTM A106 Scope
- Covers seamless carbon steel pipe only — no welded forms
- Sizes: NPS ⅛ through NPS 48 (OD 10.3 mm to 1219 mm)
- Intended for: high-temperature service in petroleum refinery and power plant piping systems
- Grades: A, B, and C (Grade B is the dominant specification)
Grade Coverage
| Standard | Grade | Type/Form | Primary Application |
|---|---|---|---|
| A53 | A | Type E (ERW), Type S (SMLS), Type F | Low-pressure steam, HVAC, structural |
| A53 | B | Type E (ERW), Type S (SMLS) | General pressure piping |
| A106 | A | Seamless only | Moderate-temperature piping |
| A106 | B | Seamless only | High-temperature process piping (most common) |
| A106 | C | Seamless only | Highest-strength carbon steel pipe application |
Chemical Composition Requirements
ASTM A53 — Chemical Composition (wt%, ladle analysis)
| Element | Grade A | Grade B |
|---|---|---|
| C max | 0.25 | 0.30 |
| Mn | 0.95 max | 0.30–1.06 |
| P max | 0.05 | 0.05 |
| S max | 0.045 | 0.045 |
| Si min | — | — |
| Cu max | 0.40 | 0.40 |
| Ni max | 0.40 | 0.40 |
| Cr max | 0.40 | 0.40 |
| Mo max | 0.15 | 0.15 |
| V max | 0.08 | 0.08 |
For Type E (ERW) and Type S (SMLS) pipe, the limits above apply. Type F (furnace-butt-welded) is limited to Grade A only and is not suitable for pressure applications above 175 °C.
ASTM A106 — Chemical Composition (wt%, ladle analysis)
| Element | Grade A | Grade B | Grade C |
|---|---|---|---|
| C max | 0.25 | 0.30 | 0.35 |
| Mn | 0.27–0.93 | 0.29–1.06 | 0.29–1.06 |
| P max | 0.035 | 0.035 | 0.035 |
| S max | 0.035 | 0.035 | 0.035 |
| Si min | 0.10 | 0.10 | 0.10 |
| Cu max | 0.40 | 0.40 | 0.40 |
| Ni max | 0.40 | 0.40 | 0.40 |
| Cr max | 0.40 | 0.40 | 0.40 |
| Mo max | 0.15 | 0.15 | 0.15 |
| V max | 0.08 | 0.08 | 0.08 |
Key chemistry difference between A53 and A106:
- A106 specifies a minimum silicon of 0.10% to ensure adequate deoxidation for seamless production and elevated-temperature service
- A106 has lower P and S limits (0.035 max each) versus A53 (P 0.05, S 0.045 max)
- A106 specifies a minimum Mn based on carbon content (the lower the C, the lower the Mn floor)
Mechanical Properties
ASTM A53 — Mechanical Properties
| Property | Grade A | Grade B |
|---|---|---|
| Min Tensile Strength MPa (ksi) | 330 (48) | 415 (60) |
| Min Yield Strength MPa (ksi) | 205 (30) | 240 (35) |
| Elongation in 50 mm min % (longitudinal) | 35 | 30 |
| Bending test | Required (Type E and S) | Required |
| Flattening test | Required (Type E and S) | Required |
Type F pipe (furnace-butt-welded) has no tensile test requirement; instead a flattening test is mandatory. Type F is Grade A only.
ASTM A106 — Mechanical Properties
| Property | Grade A | Grade B | Grade C |
|---|---|---|---|
| Min Tensile Strength MPa (ksi) | 330 (48) | 415 (60) | 485 (70) |
| Min Yield Strength MPa (ksi) | 205 (30) | 240 (35) | 275 (40) |
| Elongation in 50 mm min % (longitudinal) | 35 | 30 | 30 |
| Elongation in 50 mm min % (transverse) | 25 | 16.5 | 16.5 |
A106 uses a formula-based minimum elongation: elongation% = 625,000 / UTS (psi) for longitudinal specimens, with floor values as above.
Hydrostatic Test Requirements
Both standards require each length of pipe to be hydrostatically tested at the mill.
ASTM A53 Hydrostatic Test Pressure
Test pressure is calculated using the formula:
P = 2St / D
Where:
- P = hydrostatic test pressure (psi)
- S = allowable fiber stress = 60% of specified min YS
- t = specified wall thickness (in.)
- D = specified outside diameter (in.)
Maximum test pressure: 2500 psi (17.2 MPa) for NPS ≤ 3; schedule-dependent for larger sizes.
ASTM A106 Hydrostatic Test Pressure
Same formula applies: P = 2St / D, with S = 60% of min yield strength for Grade B = 144 MPa (21,000 psi). The purchaser may waive the hydrostatic test and substitute nondestructive electric test (NDET) — typically electromagnetic inspection — by specifying the appropriate supplementary requirement.
ASME Equivalents
| ASTM Standard | Grade | ASME Equivalent | ASME Code Section |
|---|---|---|---|
| A53 Type E, Gr A | — | SA-53 Type E, Gr A | Sec II Part A |
| A53 Type E, Gr B | — | SA-53 Type E, Gr B | Sec II Part A |
| A53 Type S, Gr A | — | SA-53 Type S, Gr A | Sec II Part A |
| A53 Type S, Gr B | — | SA-53 Type S, Gr B | Sec II Part A |
| A106 Gr A | — | SA-106 Gr A | Sec II Part A |
| A106 Gr B | — | SA-106 Gr B | Sec II Part A |
| A106 Gr C | — | SA-106 Gr C | Sec II Part A |
SA-53 and SA-106 are adopted in ASME BPVC Section II Part A without technical changes. For pressure piping designed to ASME B31.3 (Process Piping) or B31.1 (Power Piping), the SA- designation is required for code compliance.
Temperature Service Limits
ASTM A53 (SA-53) — Allowable Stress Table (ASME B31.3)
| Temperature °C | Grade A SMLS MPa | Grade B SMLS MPa | Grade B ERW MPa |
|---|---|---|---|
| −29 to 38 | 103 | 103 | 103 |
| 100 | 103 | 103 | 96.5 |
| 150 | 103 | 103 | 96.5 |
| 200 | 103 | 103 | 96.5 |
| 260 | 96.5 | 96.5 | 89.6 |
| 315 | 93.1 | 93.1 | — |
| 370 | 82.7 | 82.7 | — |
Type E (ERW) pipe carries a weld joint efficiency factor of 0.85 under ASME B31.3, reducing the allowable stress. At elevated temperatures, ERW is not listed above 315 °C.
ASTM A106 (SA-106) — Allowable Stress Table (ASME B31.3)
| Temperature °C | Grade A MPa | Grade B MPa | Grade C MPa |
|---|---|---|---|
| −29 to 38 | 103 | 103 | 117 |
| 100 | 103 | 103 | 117 |
| 200 | 103 | 103 | 117 |
| 260 | 96.5 | 103 | 110 |
| 315 | 93.1 | 96.5 | 107 |
| 370 | 82.7 | 82.7 | 96.5 |
| 425 | 68.9 | 68.9 | 75.8 |
| 455 | 55.2 | 55.2 | 62.1 |
| 480 | — | — | — |
A106 Grade B is typically used to a maximum of approximately 425–455 °C in steam and hydrocarbon service. Above 480 °C, alloy steel (e.g., A335 P11, P22) is required.
Cross-Standard Equivalents
| ASTM | Grade | EN 10216-1 / EN 10217-1 | JIS G3454/G3455 | IS 1239 / IS 3589 |
|---|---|---|---|---|
| A53 Gr A | Type S/E | P195TR2 (approx) | STPG370 | Medium class (approx) |
| A53 Gr B | Type S/E | P235TR2 | STPG410 | IS 3589 Gr410 |
| A106 Gr A | Seamless | P235GH (EN 10216-2) | STPT370 | — |
| A106 Gr B | Seamless | P265GH / P235TR2 (EN 10216-1) | STPT410 | IS 3589 Gr410 (approx) |
| A106 Gr C | Seamless | P310GH (approx) | STPT480 | — |
EN 10216-1 covers seamless steel tubes for pressure purposes in ambient and elevated temperatures. P235TR2 (A53 Gr B equivalent) and P265GH (A106 Gr B equivalent) are the most referenced EN grades for carbon steel piping substitution.
MTC Verification Checklist
When verifying a mill test certificate for A53 or A106 pipe, confirm:
- Standard designation, grade, and type (for A53: Type E, S, or F) match the purchase order
- Heat number is traceable to pipe markings
- Carbon complies with the grade maximum (and note A106 has lower P and S limits than A53)
- Silicon ≥ 0.10% reported for A106 (a mandatory minimum — absence of Si on an A106 MTC is a deficiency)
- Yield strength and tensile strength meet grade minimums
- Elongation meets the specified gauge-length minimum
- Hydrostatic test: test pressure and pass/fail result recorded (or NDET if substituted by agreement)
- For high-temperature service: confirm A106 (seamless) was specified, not A53 Type E (ERW)
- ASME applications: SA-53 or SA-106 designation is stated, not just ASTM A-designation
Frequently Asked Questions
What is the main difference between ASTM A53 and ASTM A106?
The key differences are: (1) A106 is seamless only; A53 includes ERW and furnace-butt-welded pipe. (2) A106 is specified for high-temperature service and has a minimum silicon of 0.10%; A53 does not mandate a Si minimum. (3) A106 has lower phosphorus and sulfur limits (0.035 max) versus A53 (P 0.05, S 0.045). For any elevated-temperature pressure service above approximately 200 °C, A106 Grade B seamless is preferred and is required by most piping codes.
Can ASTM A53 Grade B ERW be used for high-temperature service?
A53 Grade B ERW can be used up to approximately 315 °C under ASME B31.3, but with a reduced allowable stress due to the weld joint efficiency factor of 0.85 applied to ERW pipe. For temperatures above 315 °C or where full joint efficiency is required, A106 Grade B seamless should be specified. A53 Type F (furnace-butt-welded) is generally limited to ambient-temperature non-pressure applications.
Is SA-106 Grade B the same as ASTM A106 Grade B?
Yes. ASME SA-106 Grade B adopts ASTM A106 Grade B into the ASME Boiler and Pressure Vessel Code Section II Part A without technical changes. For piping systems built to ASME B31.1 or B31.3, the purchase order must specify SA-106, not A106, to satisfy code material traceability requirements.
What is the EN equivalent of ASTM A106 Grade B?
The closest EN equivalent is P265GH per EN 10216-2 (seamless steel tubes for pressure purposes at elevated temperatures) or P235TR2 per EN 10216-1 (for ambient temperature applications). P265GH has a minimum yield of 265 MPa and is used in boiler and heat exchanger tubing, making it the closest match to A106 Gr B for elevated-temperature piping.
Does ASTM A53 cover galvanized pipe?
Yes. ASTM A53 covers both black (uncoated) and hot-dipped galvanized pipe. The galvanizing requirements are specified in the standard and include zinc coating weight and adhesion tests. Galvanized A53 pipe is commonly used in fire sprinkler systems, water supply, and gas distribution piping.
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