ASTM A105 Specification

What is ASTM A105?

ASTM A105/A105M is a forged carbon steel material standard developed by the American Society for Testing and Materials (ASTM), specifically for the manufacture of pipe flanges, valves, fittings and other high-pressure components.

Scope of application:
ASTM A105 and ASME SA105 cover seamless forged carbon steel pipe components for normal and high temperature pressure systems.

This standard specification is mainly applicable to various pipe fittings in pipeline systems, such as pipe flanges, elbows, tees, reducers, valves and other various parts, and is widely used in pipeline connections and transportation systems in industries such as petroleum, chemical, power, and construction. It can be ordered according to customer dimensions or industry standards (such as MSS, ASME and API specifications), all of which are included in the scope of application.

Applicable temperature:
Conventional range: -29°C ~ 425°C
Low temperature limit: impact test is required below -29°C (such as A350 LF2 is more applicable)
High temperature risk: graphitization may occur at >425°C, and it is recommended to use chromium-molybdenum steel (such as A182 F11) instead.

Chemical composition (%):

A105 material has clear content regulations for major elements such as carbon, silicon, manganese, sulfur, and phosphorus. Its key parameters are as follows:

Carbon (C) ≤ 0.35
Silicon (Si): 0.10~0.35
Manganese (Mn): 0.60 ~ 1.05
Phosphorus (P) ≤ 0.035
Sulfur (S) ≤ 0.040

In addition. It may also contain a certain amount of copper, nickel, molybdenum, vanadium, chromium and other elements as needed.

Mechanical properties:

Tensile strength ≥ 485 MPa;
Yield strength ≥ 250 MPa;
Elongation after fracture ≥ 22% (gauge length 50mm);
Sectional shrinkage ≥ 30%;
Hardness ≤ 187 HB (Brinell).

Manufacturing process:

- Forging: The forging ratio is usually required to be greater than 5. Through multiple upsetting and drawing processes, the defects such as pores and looseness in the raw materials are eliminated, the grains are refined, and the density and uniformity of the materials are improved. The alloy is forged between 1,700 degrees Fahrenheit and 2,200 degrees Fahrenheit, and then quenched and tempered.

- Heat treatment: Generally, the heat treatment process of normalizing and tempering is adopted to eliminate forging stress, improve the organizational structure of the material, improve its comprehensive performance, and provide a good organizational state for subsequent processing and use.

Except for flanges above 300 pounds, special design flanges with unknown design pressure or design temperature, and parts above 4 inches NPS and above 300 pounds, heat treatment is not a mandatory requirement. If heat treatment is required, annealing, normalizing, normalizing and tempering, normalizing quenching and tempering, etc. should be used.

Typical application scenarios:

Oil and gas: pipeline flanges, valve housings (Class 150~2500).
Power industry: medium and low pressure steam systems (≤425°C).
Chemical equipment: pipe fittings for non-corrosive media (such as water, oil, and air).
General industry: pump and compressor inlet and outlet connectors.

Common product forms:

Flanges: butt welding flanges (WN), socket welding flanges (SW), blind flanges (BL), etc.
Fittings: elbows, tees, reducers (must comply with ASME B16.9/B16.11).
Valve components: valve body, valve cover.

Supporting standards and certifications:

Manufacturing standards: ASME B16.5 (flanges), ASME B16.11 (socket welding pipe fittings).
Special certification: NACE MR0175 (resistance to hydrogen sulfide corrosion, sulfur/phosphorus content must be controlled).

Inspection and test requirements:

- Appearance inspection: The surface of the pipe fittings should be smooth, without defects such as cracks, folds, scars, burrs, etc., and the surface roughness should meet the requirements of relevant standards.

- Dimensions and tolerances: The outer diameter, wall thickness, length, angle and other dimensions of the pipe fittings should meet the tolerance range specified in the standard to ensure the interchangeability and sealing of the pipe fittings during installation and use.

- Physical and chemical performance tests: Including tensile tests, impact tests, hardness tests, etc., to verify whether the material meets the mechanical performance requirements specified in the standard. At the same time, tests such as chemical composition analysis may also be carried out to ensure that the chemical composition of the material meets the requirements.

- Non-destructive testing: Ultrasonic testing, magnetic particle testing or penetration testing are usually used to perform non-destructive testing on pipe fittings to detect defects such as cracks that may exist inside and on the surface.

Comparison of A105 with other carbon steel materials:

ASTM A105: General forged carbon steel, cost-effective, commonly used in medium and low pressure, non-corrosive media environments.
ASTM A182 F304: Stainless steel material, corrosion-resistant, high cleanliness. Commonly used in the chemical and food industries.
ASTM A350 LF2: Excellent low-temperature toughness (-46°C), commonly used in LNG and cryogenic pipelines.
ASTM A694 F60: High strength (yield ≥ 415 MPa), commonly used in high-pressure oil and gas pipelines.

Notes on A105 material selection:

1. Avoid over-temperature use:
>425°C can be used for a long time, graphitization may occur, resulting in a decrease in strength. It is recommended to use A182 F11/F22 (chrome-molybdenum steel) instead.
Impact test is required when it is below -29°C, and it is recommended to use A350 LF2 at extremely low temperatures (such as below -46°C).

2. Corrosive environment
Poor corrosion resistance and easy to rust. In humid, acidic or salt spray environments, an anti-corrosion layer must be applied or stainless steel (such as A182 F316) must be selected.

3. Insufficient hardness and wear resistance
The hardness is low (≤187 HB), which is not suitable for high wear conditions (such as media containing solid particles). The surface is easy to scratch, and a hardened layer needs to be welded or a wear-resistant alloy needs to be used.

4. Welding process
Preheating (about 150°C) and interlayer temperature control are required to prevent cold cracks.

5. Special environmental restrictions
NACE MR0175 is not met: high sulfur environment (acidic oil and gas) requires strict sulfur control (S≤0.02%), and ordinary A105 may not meet the standard.

Conclusion:

ASTM A105 is the "Gold Standard" for carbon steel flanges and pipe fittings. With good mechanical properties and cost advantages, it has become the preferred material for industries such as oil and power. However, materials must be selected carefully in high temperature, low temperature or corrosive environments!

Read more: Types and specifications of forged flanges or Stainless steel pipe fittings vs Carbon steel pipe fittings