ASTM A106 Grade B: Complete Specification Guide for MTR Verification

What Is ASTM A106?

ASTM A106/A106M is the specification for seamless carbon steel pipe for high-temperature service. It is one of the most widely used pipe specifications in the pressure equipment, power generation, and process piping industries.

The specification covers three grades — A, B, and C — with increasing strength. Grade B is by far the most commonly specified, accounting for the majority of carbon steel seamless pipe in refinery, petrochemical, and power plant applications.

ASTM A106 pipe is used in applications governed by ASME B31.1 (Power Piping), ASME B31.3 (Process Piping), and ASME Boiler and Pressure Vessel Code construction. The corresponding ASME designation is SA-106, which adopts ASTM A106 with additional supplementary requirements for code construction.

What Are the ASTM A106 Grade B Chemical Composition Limits?

ASTM A106 Grade B chemical composition limits (heat analysis, per ASTM A106 Table 1):

• •Carbon (C): 0.30% max
• •Manganese (Mn): 0.29% to 1.06%
• •Phosphorus (P): 0.035% max
• •Sulfur (S): 0.035% max
• •Silicon (Si): 0.10% min
• •Chromium (Cr): 0.40% max
• •Copper (Cu): 0.40% max
• •Molybdenum (Mo): 0.15% max
• •Nickel (Ni): 0.40% max
• •Vanadium (V): 0.08% max

Product analysis limits are wider than heat analysis limits. For example, the product analysis carbon limit is 0.33% (vs 0.30% for heat analysis). This accounts for chemistry variation across the cross-section of the product.

Note: the sum of Cr, Cu, Mo, Ni, and V must not exceed 1.00%.

What Are the ASTM A106 Grade B Mechanical Property Requirements?

ASTM A106 Grade B mechanical property requirements (per ASTM A106 Table 2):

• •Tensile Strength: 60 ksi (415 MPa) minimum
• •Yield Strength: 35 ksi (240 MPa) minimum
• •Elongation (2 in.): 30% minimum (for standard round specimens)

Elongation requirements are adjusted for pipe wall thickness and specimen geometry. Thinner-wall pipe may have reduced elongation requirements calculated per the equations in ASTM A106 Section 7.

There is no maximum tensile or yield strength requirement in ASTM A106, unlike API 5L PSL2 where both minimum and maximum values apply. However, some purchaser specifications add maximum hardness requirements for sour service or NACE compliance.

What Should You Verify on Every ASTM A106 Grade B MTR?

When reviewing an ASTM A106 Grade B MTR, verify:

• •Grade designation: Confirm the MTR specifies Grade B (not Grade A or C). This determines which mechanical requirements apply.

2. Carbon content: 0.30% max (heat analysis). This is the most frequently marginal value — many Grade B heats have carbon between 0.25% and 0.30%.

3. Manganese range: 0.29% to 1.06%. Note this is a range, not just a maximum. Manganese below 0.29% is non-conformant.

4. Silicon minimum: 0.10% min. This is a minimum requirement, not a maximum. Silicon below 0.10% indicates insufficient deoxidation.

5. Yield strength: 35 ksi (240 MPa) minimum. Verify units — some mills report in MPa, others in ksi.

6. Elongation: 30% minimum for standard specimens. Check whether the reported value applies to a 2-inch or 8-inch gauge length, and verify the applicable elongation requirement for the specimen type.

7. Hydrostatic test pressure: ASTM A106 requires hydrostatic testing to specified pressures based on pipe size and wall thickness. The test pressure must be reported on the MTR.

What Is the Difference Between ASTM A106 and ASME SA-106?

ASME SA-106 adopts ASTM A106 identically for Boiler and Pressure Vessel Code construction. The key differences:

• •SA-106 material must be produced to the specific ASTM A106 edition referenced in the applicable ASME Code edition.
• •SA-106 may include additional supplementary requirements specified in ASME Section II, Part A.
• •Material certified to ASTM A106 can generally be used as SA-106, provided it meets the same specification edition and any ASME supplementary requirements.

The MTR should reference the applicable specification — either ASTM A106 or ASME SA-106 — as specified in the purchase order. For ASME Code construction, SA-106 is the correct designation.

How Does MTR.AI Verify ASTM A106 Compliance?

MTR.AI has the complete ASTM A106 specification logic built in — all three grades, both heat and product analysis limits, mechanical property requirements, and hydrostatic test pressure calculations.

When you upload an ASTM A106 Grade B MTR, MTR.AI extracts every reported value and compares it against Table 1 (chemistry) and Table 2 (mechanicals). It checks the manganese range (not just maximum), verifies the silicon minimum, and flags any value at or near the specification limit.

The result is a complete compliance report with element-level verdicts — no manual table lookups, no unit conversion errors, no missed non-conformances.