ASTM A106 Pipe

ASTM A106—Standard Specification for Seamless Carbon Steel Pipe for High-Temperature Service

ASTM A106 pipe is always produced by the seamless method and can be bent, coiled and flanged.

Sizes

1” – 26” dependent on OD vs Wall Ratio

ASTM A106 Seamless Pipes (also known as ASME SA106 pipes) are commonly used in the construction of oil and gas refineries, power plants, petrochemical plants, boilers and ships. These pipes must transport fluids and gases at higher temperatures and pressures. ASTM A106 pipe includes three grades, A106 Grade A, A106 Grade B, and A106 Grade C. Among them, grade A has relatively lower strength requirements; grade B is widely used and has a better overall performance balance; grade C has higher standards in strength and toughness, and can cope with more stringent high-temperature and high-pressure scenarios.

About ASTM A106 Grade B:
ASTM A106 Grade B Pipe (also known as ASME SA106 GR.B pipes)  is used in power plants, boilers, petrochemical plants, oil and gas refineries, and ships where the piping must transport hot or cold liquids and gases under high pressures and temperatures. A106 GR. B Carbon Steel Seamless Pipes, A106 Gr B Sch 40 pipe, ASTM A106 Grade B Pipe Suppliers is available in various weights, sizes, and black and galvanized grades both seamless and electric welded. ASTM A106 Grade B Pipe sizes, less than 2" is it normally delivered as a cold drawn product. 2" and up are usually hot finished.

About ASTM A106 Grade C:
ASTM A106 Grade C Pipe (also known as ASME SA106 GR.C pipes) is a carbon-manganese steel pipe for high-temperature large-diameter boilers and superheaters. Its chemical composition is simple and similar to 20G carbon steel, but its carbon and manganese content is higher, so its yield strength is about 12% higher than that of 20G, and its plasticity and toughness are not bad. The steel has a simple production process and good cold and hot workability. Using it to replace 20G headers (economizer, water wall, low-temperature superheater and reheater header) can reduce the wall thickness by about 10%, which can save material costs, reduce welding workload, and improve headers The stress difference at start-up.

Mechnical Properties  of ASTM A106:

ASTM A106	Grade A	Grade B	Grade C
Tensile Strength (Mpa)	≥330	≥415	≥485
Yield Strength (Mpa)	≥205	≥240	≥275
Elongation (%)	≥35	≥30	≥30

Key differences:
Grade C has the highest strength (yield strength ≥ 275MPa) and is suitable for extreme high-pressure environments, such as supercritical boiler pipes.
Grade B is the most commonly used (yield strength ≥ 240MPa), suitable for medium and high-pressure scenarios such as refineries and power plants.
Grade A has the lowest strength and is suitable for general industrial uses such as low-pressure steam and water transportation.

Chemical Composition of ASTM A106:

Element	Grade A	Grade B	Grade C
Carbon max. %	0.25	0.30	0.35
Manganese %	0.27 – 0.93	0.29 – 1.06	0.29 – 1.06
Phosphorus max %	0.035	0.035	0.035
Sulfur max %	0.035	0.035	0.035
Silicon, min %	0.10	0.10	0.10

Chemical composition characteristics:

Carbon element (C): The carbon content of grade A does not exceed 0.25%, the carbon content of grade B is 0.25-0.30%, and the carbon content of grade C is 0.30-0.35%. Carbon is a key factor affecting strength. The gradual increase in content corresponds to a gradual increase in strength, but too high a carbon content will also increase the tendency to harden and affect toughness, so the carbon content of each grade has a strict range.

Manganese (Mn): The manganese content is roughly 0.29-1.06% in the three grades. Manganese can refine grains, strengthen ferrite, provide additional tensile and compressive resistance for steel pipes, and assist in improving overall mechanical properties.
Silicon (Si): The silicon content is maintained at around 0.10%. It mainly plays a deoxidizing role, purifies molten steel, indirectly guarantees the quality of steel, and makes the internal structure more uniform.

Impurity control: The content of phosphorus and sulfur impurity elements is strictly limited, not exceeding 0.035%. The purpose of limiting impurities is to avoid inclusions, which will weaken the force performance of steel pipes and reduce their reliability.

Comparison of typical application scenarios:

A106 GR.A: Commonly used in low-pressure fluid transportation and building structure fields, such as general industrial pipelines and low-pressure steam systems.
A106 GR.B: Commonly used in petrochemical, electric power, and boiler fields, such as refinery pipelines, power plant steam pipes, and high-pressure boiler pipes.
A106 GR.C: Commonly used in ultra-high pressure and high temperature systems and nuclear power fields, such as supercritical power plants, deep-sea oil and gas extraction, and auxiliary pipelines of nuclear power plants.

Key differences:
Grade B is the most widely used, covering more than 90% of high-temperature and high-pressure pipeline needs, such as cracking units in refineries.
Grade C is used in more severe environments, such as supercritical pressure boilers (>22.1MPa).
Grade A has a lower cost and is suitable for non-critical low-pressure systems.

How to choose the right grade?

Temperature ≤450°C, pressure ≤5MPa → Grade A (economical)
Temperature ≤650°C, pressure ≤15MPa → Grade B (most commonly used)
Temperature ≤700°C, ultra-high pressure conditions → Grade C (special needs)

Comparison of A106 pipe with other standards:

ASTM A53: low-pressure general-purpose pipeline, weldable, low strength, not suitable for high temperatures.
API 5L: long-distance oil and gas pipelines, focusing on pressure resistance & corrosion resistance, not emphasizing high temperature performance.
ASTM A335: Alloy steel high temperature pipe, containing Cr-Mo alloy, temperature resistance >700°C.

Manufacturing process:
ASTM A106 seamless steel pipe can be manufactured by two processes: cold drawing and hot rolling. The two processes differ in production process, precision, surface quality, minimum size, mechanical properties, organizational structure, etc. For example, the precision and surface quality of cold drawn tubes are usually higher than those of hot rolled tubes, but the minimum size is larger, and the mechanical properties and organizational structure are slightly different. The hot rolling process is more suitable for large-scale production.

① Main production process of hot-rolled seamless steel pipe:
Pipe blank preparation and inspection → pipe blank heating → perforation → pipe rolling → steel pipe reheating → sizing (reducing) diameter → heat treatment → finished pipe straightening → finishing → inspection (non-destructive, physical and chemical, bench inspection) → storage

② Main production process of cold-rolled (drawn) seamless steel pipe:
Blank preparation → pickling and lubrication → cold rolling (drawing) → heat treatment → straightening → finishing → inspection

There are two methods of cold processing: one is the cold drawing method, which is to pull the steel pipe through the pipe drawing die to make the steel pipe gradually thinner and elongated; the other method is the cold rolling method, which is a method of applying the hot rolling mill invented by the Monnesmann brothers to cold processing. Cold processing of seamless steel pipes can improve the dimensional accuracy and processing finish of steel pipes, improve the mechanical properties of materials, etc.

ASTM A106 seamless steel pipes are widely used in various industries, including petroleum, chemical, boilers, power stations, ships, machinery manufacturing, automobiles, aviation, aerospace, energy, geology, construction and military industry. These industries have different requirements for steel pipes, but ASTM A106 seamless steel pipe, as a universal material, can meet the basic needs of most industries.

Process:
The steel shall be killed steel, with the primary meltling process being open-hearth,basic-oxygen,or electric-furnace,possibly combined with separate degassing or refining. If secondary melting, using electroslag remelting or vacuum-arc remelting is subsequently employed, the heat shall be defined as all of the ingots remelted from a single primary heat.

Steel cast in ingots or strand cast is permissible. When steels of different grades are sequentially strand cast, identification of the resultant transition material is required. The producer shall remove the transition material by any established procedure that positively separates the grades.

Heat treatment:
Hot-finished pipe need not be heat treated.When hot finished pipe is heat treated, it shall be heat treated at a temperature of 1200°F(650℃) or higher.

Cold drawn pipe shall be heat treated after the final cold draw pass at a temperature of 1200°F(650℃) or higher.

Bending requirements:
For pipe NPS2(DN50) and under, a sufficient length of pipe shall stand being bent cold through 90°around a cylindrical mandrel, the diameter of which is twelve times the outside diameter(as shown in ASME B 36.10M) of the pipe,without developing cracks. Wehn ordered for close coiling, the pipe shall stand being bent cold through 180°around a cylindrical mandrel. the diameter of which is eight times the outside diameter (as shown in ASME B 36.10M) of the pipe, without failure.

Hydrostatic test:
Each length of pipe shall be subjected to the hydrostatic test without leakage through the pipe wall.

As a alternative to the hydrostatic test at the option of the manufacturer or where specified in the purchase order, it shall be permissible for the full body of each pipe to be tested with a nondestructive electric test.

Where the hydrostatic test and the nondestructive electric test are omitted and the lengths marked with the letters"NH",the certification,where required,shall clearly state"Not Hydrostatically Tested" , and the letters"NH" shall be appended to the product specification number and material grade shown on the certification.

Non-destructive electric test:
As an alternative to the hydrostatic test at the option of the manufacturer or where specified in the purchase order as an alternative or addition to the hydrostatic test, the full body of each pipe shall be tested with a nondestructive electric test. In such cases. the marking of each length of pipe so furnished shall include the letters"NDE".It is the intent of this nondestructive electric test to reject pipe with imperfections the produce test signals equal to or greater than that produced by the applicable calibration standard.

Where the nondestructive electric test is performed, the lengths shall be marked with the letters"NDE". The certification, where required, shall state"Nondestructive Electric Tested" and shall indicate which of the tests was applied. Also, the letters"NDE"shall be appended to the product specification number and material grade shown on the certification.

The ultrasonic testion referred to in this specification is capable of detecting the presence and location of significant longitudinally or circumferentially oriented imperfections:however,differently oriented imperfections. Ultrasonic testing is not necessarily capable of detecting short, deep imperfection.

The eddy current examination referened in this sepcification has the capability of detecting significant imperfections,especially of the short abrupt type.

The flux leakage examination referred to in this specification is capable of detecting the presence and location of signficant longitudinally or transversely oriented imperfections,however,different techniques need to be employed for the detection of such differently oriented imperfections.