What Is ASTM A105?

What Does ASTM A105 Mean?

ASTM A105 is a material specification for forged carbon steel components used in pressure piping systems at ambient and higher temperatures. It covers forged parts such as flanges, fittings, valves, and other pressure-containing components. Issued by ASTM International, the specification defines requirements for chemical composition, mechanical properties, heat treatment, and testing.

The designation ASTM A105 identifies a material specification rather than a pipe size, pressure class, or flange dimension.The full standard designation is ASTM A105/A105M — Standard Specification for Carbon Steel Forgings for Piping Applications.
The term can be understood as follows:

Term	Meaning
ASTM	ASTM International, the standards organization
A105	Specification number for carbon steel forgings
A105/A105M	Inch-pound and SI-unit versions of the specification
Carbon steel	The material category
Forgings	Components manufactured through a forging process
Piping applications	Components intended for pressure piping systems

ASTM A105 applies to forged piping components for ambient and higher-temperature pressure service. The standard includes flanges, fittings, valves, and similar components.
It is important not to interpret “A105” as a pipe grade. A105 is primarily associated with forged pressure-piping components.

ASTM A105 Specification

ASTM A105/A105M covers forged carbon steel piping components for pressure systems at ambient and elevated temperatures. The specification applies to components such as flanges, forged fittings, valves, and other parts manufactured to standard or customer-specified dimensions.
The main ASTM A105 specification requirements are summarized below.

Specification	ASTM A105/A105M
Material	Forged carbon steel
Product Type	Flanges, fittings, valves, and other pressure piping components
Tensile Strength	70 ksi (485 MPa) min
Yield Strength	36 ksi (250 MPa) min
Elongation in 2 in.	22% min
Reduction of Area	30% min
Hardness	187 HBW max
Carbon	0.35% max
Manganese	0.60–1.05%
Phosphorus	0.035% max
Sulfur	0.040% max
Silicon	0.10–0.35%
Copper	0.40% max
Nickel	0.40% max
Chromium	0.30% max
Molybdenum	0.12% max
Vanadium	0.08% max
Common Heat Treatment	Annealing, normalizing, or normalizing and tempering, when required

Chemical Composition of ASTM A105

Element	Composition (%)
Carbon (C)	≤ 0.35
Manganese (Mn)	0.60 – 1.05
Phosphorus (P)	≤ 0.035
Sulfur (S)	≤ 0.040
Silicon (Si)	0.10 – 0.35
Copper (Cu)	≤ 0.40
Nickel (Ni)	≤ 0.40
Chromium (Cr)	≤ 0.30
Molybdenum (Mo)	≤ 0.12

Heat Treatment Requirements
ASTM A105 components may be supplied in a normalized, normalized and tempered, or quenched and tempered condition.
Heat treatment is required for components with section thickness >4 inches.
Normalizing is often applied to improve mechanical consistency and grain refinement.
In some cases, stress relieving may be performed after machining or welding to minimize residual stresses.

Mechanical Properties of ASTM A105

Property	Value
Tensile strength (psi) min	70,000 psi
Yield strength (psi) min	36,000 psi
Elongation in 2″ (%) min	22%
Reduction of area (%) min	30%
Brinell Hardness (BHN) max	187

ASTM A105 Equivalent Material

Engineers and buyers often look for ASTM A105 equivalent materials when sourcing forged carbon steel components from different countries and standards. While ASTM A105 is the most widely used specification for forged flanges, fittings, and valves in North America, several comparable grades are available worldwide.
The most common direct equivalent is ASME SA105, which shares the same chemical composition, mechanical properties, and application requirements. ASTM A105N is another commonly specified grade, referring to ASTM A105 material supplied in the normalized condition for improved grain structure and mechanical consistency.
For low-temperature applications, ASTM A350 LF2 is often selected as an alternative because it provides enhanced impact toughness and better performance in cold environments.
When a cast component is required instead of a forging, ASTM A216 WCB is generally considered the closest casting equivalent to ASTM A105.
Common international equivalents include:

Region	Grade
Europe	P245GH, GS-C25
Japan	SFVC1
China	20Mn

Although these materials offer similar performance, material substitution should always be verified against project specifications, operating temperatures, pressure requirements, and applicable industry standards.
ASME SA105 is the corresponding ASME Code designation based on ASTM A105 requirements. For a detailed comparison, see our guide to ASTM A105 vs ASME SA105.

ASTM A105 Temperature Range

ASTM A105 is intended for pressure piping components used at ambient and elevated temperatures. The allowable service temperature depends on the applicable pressure-temperature rating, design conditions, and construction code.

Typical Applications of ASTM A105

Its mechanical properties make it especially well-suited for both high-temperature and high-pressure environments.

Certifications & Standards of ASTM A105

ASTM A105 vs A350 LF2 Flanges: Key Differences and Material Selection

ASTM A105 and ASTM A350 LF2 are both forged carbon steel materials used for flanges and other pressure-containing components. The main difference is their suitability for low-temperature service. A105 is commonly selected for general and elevated-temperature applications, while A350 LF2 is designed for applications where impact toughness at low temperatures is required.

Feature	ASTM A105	ASTM A350 LF2
Material Type	Forged carbon steel	Forged carbon steel
Main Service	General and elevated-temperature service	Low-temperature service
Tensile Strength	≥ 485 MPa	≥ 485 MPa
Yield Strength	≥ 250 MPa	≥ 250 MPa
Impact Testing	Not generally required by the material specification	Required for LF2 Class 1 when specified by the applicable requirements
Low-Temperature Toughness	Limited compared with LF2	Improved through impact testing and material requirements
Typical Applications	Oil & gas, refineries, steam and industrial piping	LNG, low-temperature piping, offshore and cold-service applications
Cost & Availability	Generally lower cost and widely available	Generally higher cost due to additional requirements

Choose ASTM A105 when the piping system operates within its allowable temperature range and does not require specific low-temperature impact toughness. Choose ASTM A350 LF2 when the design requires verified impact toughness for low-temperature service.The final material selection should be based on the applicable ASME pressure-temperature ratings, design temperature, impact testing requirements, and project specifications rather than temperature alone.

ASTM A105 Welding

ASTM A105 is generally considered a weldable forged carbon steel. Its relatively low carbon content allows it to be welded using common processes such as SMAW, GTAW, and GMAW. However, the welding procedure should consider the component thickness, carbon equivalent, service conditions, and applicable welding code.

ASTM A105 Welding Procedure
For pressure-containing components, welding should follow a qualified Welding Procedure Specification (WPS). Low-hydrogen welding practices are recommended to reduce the risk of hydrogen cracking. Common filler metals include E7018 electrodes for SMAW and suitable ER70-series filler metals for GTAW or GMAW, depending on the qualified WPS.

Preheat and PWHT
Preheating may be required based on material thickness, carbon equivalent, restraint, and welding conditions. The required temperature should be established by the qualified WPS rather than using a single value for all A105 components.For weld repairs, ASTM A105 includes specific requirements for post-weld heat treatment (PWHT). The repair procedure and subsequent heat treatment must comply with the applicable ASTM A105 requirements and construction code.

ASTM A105 Welding Considerations

Factor	Key Requirement
Weldability	Generally good
Welding Processes	SMAW, GTAW, GMAW
Filler Metal	Selected according to WPS
Preheat	Based on WPS and welding conditions
Hydrogen Control	Low-hydrogen practice recommended
PWHT	Applicable to weld repairs and code requirements

For critical piping applications, ASTM A105 welding should be qualified and controlled according to the applicable ASME Section IX and project requirements.

ASTM A105 Pressure Class

ASTM A105 specifies the forged carbon steel material, not the pressure class of a flange. The pressure class is defined by the applicable flange standard, such as ASME B16.5 or ASME B16.47.
ASTM A105 flanges may be specified with pressure classes such as:
Class 150
Class 300
Class 400
Class 600
Class 900
Class 1500
Class 2500
Here, ASTM A105 identifies the flange material, while the Class designation defines its pressure-temperature rating.
For example, an ASTM A105 Class 300 flange is not simply rated for 300 psi. Its allowable working pressure depends on the pressure class, operating temperature, flange size, material group, and applicable standard. The allowable pressure generally decreases as operating temperature increases.
Therefore, ASTM A105 alone cannot determine the working pressure of a flange. The A105 material specification and the applicable ASME pressure-temperature rating must be considered together when selecting a flange for a piping system.

FAQ

Is ASTM A105 carbon steel or stainless steel?
ASTM A105 is carbon steel. It is not a stainless steel specification.

What are ASTM A105 flanges?
ASTM A105 flanges are carbon steel forged flanges manufactured from material meeting ASTM A105 requirements. Their dimensions and pressure class are normally specified by another applicable standard, such as ASME B16.5.

What is ASTM A105 used for?
ASTM A105 is commonly used for carbon steel flanges, forged fittings, valve components, and similar pressure-containing piping components.

Is A105 the same as A105N?
Not exactly. A105 identifies the material specification, while “A105N” is commonly used to indicate a normalized condition. The required heat treatment should be confirmed from the applicable specification and purchase order.

What is the difference between A105 and A234 WPB?
A105 is primarily a specification for forged carbon steel components, while A234 WPB is commonly used for wrought carbon steel butt-welding fittings.

What is the difference between A105 and A350 LF2?
A105 is commonly used for general pressure-piping service. A350 LF2 is intended for applications requiring low-temperature toughness and impact testing requirements.