SA-350 vs SA-105

A comparison between SA-350 and SA-105

(Ref: ASME BPVC Ed 2019)

Similarities

(Considering LF2 grade of SA-350)

1. Min. Tensile Strength: 70,000 PSI

2. Min. Yield Strength: 36,000 PSI

3. Min. Elongation: 22%

4. Min. Reduction in Area: 30

5. Max. Allowable Stress at 100F: 20,000 PSI

6. Max. Allowable Stress at 800F: 12,000 PSI

7. P-No. 1, Group No. 2

Differences

1. Application

SA-350: For low-temperature service with Charpy V-notch impact testing

SA-105: For Ambient and higher temperature service

2. Manufacturing Process

SA-350: Manufacturing Process is specified.

Melting Process — The steel shall be produced by any of the following primary processes: open-hearth, basic oxygen, electric furnace, or vacuum-induction melting (VIM). The primary melting may incorporate separate degassing or refining and may be followed by secondary melting using electroslag remelting (ESR), or vacuum-arc remelting (VAR).

The steel shall be fully killed, fine-grain practice.

SA-105: Manufacturing Process is not specified.

3. Impact testing

SA-350: Impact testing is mandatory

SA-105: Impacting test is not mandatory, but if done, minimum design metal temperature (MDMT) could be reduced.

4. Heat Treatment

SA-350: Mandatory Heat Treatment is specified.

Forgings of grades other than Grade LF787 shall be furnished in the normalized, or in the normalized and tempered, or in the quenched and tempered condition.

SA-105: Heat Treatment is required only in special cases

[5.1.1 Flanges above Class 300

5.1.2 Flanges of special design where the design pressure at the design temperature exceeds the pressure-temperature ratings of Class 300, Group 1.1,

5.1.3 Flanges of special design where the design pressure or design temperature are not known,

5.1.4 Piping components other than flanges that meet both of the following criteria: (1) over NPS 4 and (2) above Class 300, and

5.1.5 Piping components of Special Class2 other than flanges which meet both of the following criteria: (1) over NPS 4 and (2) when the working pressure at the operating temperature exceeds the tabulated values for Special Class 300, Group 1.1.]

5.2 Heat treatment, when required by 5.1 shall be annealing, normalizing, or normalizing and tempering or quenching and tempering in accordance with Specification A 961

5. Hardness Range

SA-350: Max. 197

SA-105: max. 187

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