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Seamless Carbon Steel Pipe

OD Range :

6 mm – 610 mm (customizable)

WT Range :

1 mm – 50 mm (customizable according to standards and requirements)

Length :

6 m – 12 m (can be cut to specified lengths or customized to customer requirements)

Tolerance :

Outer diameter ±1%, Wall thickness ±10%, Length ±0.5% (per ASTM standard)

Material :

ASTM A106 Grade B, ASTM A53 Grade B, API 5L B, Q235, Q345, and other carbon steel materials

Standard :

ASTM A106, ASTM A53, API 5L, EN 10255, and other international standards

Surface :

Black Painted, Rust-proof Oil Coating, Hot-dip Galvanized, Pickled

Application :

High-temperature steam pipelines, boiler piping systems, petroleum, chemical, construction, mechanical equipment, and pressure pipeline systems

I. Introduction to Seamless Carbon Steel Pipes

Seamless carbon steel pipes are tubes manufactured without welded seams, formed entirely by extrusion or piercing of steel billets. Unlike welded pipes, they are produced through hot-working processes that ensure uniform wall thickness, high strength, and excellent pressure-bearing capacity. These pipes find extensive applications in industrial and municipal sectors, particularly for high-pressure, thick-walled, and critical transportation pipelines.

i. Key Features

High Strength and Pressure Resistance: Seamless construction ensures stable performance under high-pressure conditions.
Uniform Wall Thickness: Guarantees safe and reliable fluid transportation while minimizing weak points.
Exceptional Durability: Suitable for long-term operation and harsh environments.
Excellent Workability: Supports secondary processing such as bending, cutting, and welding.

ii. Common Applications

Oil and natural gas transmission pipelines
Chemical, boiler, and steam piping systems
High-pressure hydraulic and liquid transfer lines
Building structural and mechanical equipment piping

II. Common Parameters for Seamless Carbon Steel Pipes

Parameter Name	Value / Range	Description
Material	Carbon Steel	Commonly Q195, Q215, Q235, ASTM A106 Gr.B, etc.
Outer Diameter (OD)	6 mm – 660 mm	Can be customized for larger diameters upon request
Wall Thickness (WT)	2 mm – 60 mm	Selected according to design pressure; thick-wall pipes suitable for high pressure
Tolerance	±0.5% – ±1%	Allowable deviation for outer diameter and wall thickness
Length	6 m – 12 m	Cut-to-length available; special lengths can be customized
Type	Seamless	Suitable for high-pressure and thick-wall applications
Standard	ASTM A106, ASTM A53, API 5L, EN 10216-1	Common international standards
Surface Finish	Black oxide, hot-dip galvanized, epoxy coating, plastic lining	Selected based on application; optional anti-corrosion treatment
End Treatment	Plain, beveled, threaded	Easy installation; compatible with flanges or welding
Density	7.85 g/cm³	Theoretical density, used for weight calculation
Theoretical Weight	Calculated based on OD and WT	Useful for construction, design, and logistics calculations
Maximum Working Pressure	≤10 MPa (Low Pressure) / ≤25 MPa (Medium Pressure)	Determined by wall thickness and material grade
Operating Temperature	-20°C – 450°C	For high or low temperatures, select corresponding material grade

III. Core Process Types for Seamless Carbon Steel Pipes

(1) Hot-Rolled Piercing Method
Process Principle: A heated steel billet is formed into a hollow tube blank via a piercing machine or rollers, then hot-rolled to adjust outer diameter and wall thickness.
Characteristics:

Excellent wall thickness uniformity
High pressure-bearing capacity
Suitable for small to medium-large diameter pipes
Common Applications: Oil, gas, boiler piping

(2) Hot Extrusion Method
Process Principle: A heated billet is extruded through a die under high pressure to form a tube blank, followed by hot rolling to achieve final sizing.
Characteristics:

High wall thickness precision
Smooth inner surface
Suitable for thick-walled large-diameter pipes
Common Applications: High-pressure transmission pipelines, boilers, chemical process piping

(3) Cold Drawing/Cold Rolling Method for Seamless Steel Tubes
Process Principle: Further stretching or rolling of hot-rolled tube blanks via cold drawing or cold rolling to achieve higher dimensional accuracy and smoother surfaces.
Characteristics:

High dimensional accuracy, smooth appearance
Good wall thickness uniformity
Slightly higher strength than hot-rolled tubes
Common Applications: Mechanical structures, hydraulic pipes, precision industrial piping

(4) Special Process for High-Pressure Boiler Tubes
For boilers and high-pressure steam pipelines, heat treatment (normalizing, annealing, quenching and tempering) is required to enhance high-temperature and pressure resistance.
Characteristics:

Excellent high-temperature strength
Capable of withstanding high-pressure steam or liquids
Common Applications: Boilers, high-pressure steam pipelines

Summary:
Hot-Rolled Piercing Method: Suitable for general-purpose, industrial, and transport pipelines; lower cost.
Hot extrusion method: Suitable for thick-walled, large-diameter pipes with high precision and quality.
Cold drawing/cold rolling method: Suitable for high-precision, small-diameter mechanical pipes.
High-pressure boiler tube process: Suitable for high-temperature, high-pressure operating conditions.

IV. Practical Standards Comparison Table for Seamless Carbon Steel Pipes

Standard Name	Applicable Medium	Allowable Pressure / Temperature Range	Manufacturing Process	Typical Applications	Inspection Methods / Certification
ASTM A106 Gr.B / C	Water, steam, oil, gas	≤25 MPa / -29°C to 450°C	Hot-rolled seamless	High-temperature & high-pressure fluid transportation, boiler tubes	Dimensional inspection, NDT, MTC
ASTM A53 Gr.B	Water, gas, steam	≤10 MPa / -20°C to 350°C	Hot-rolled seamless / ERW welded	Municipal water supply, low-pressure gas lines, structural piping	Dimensional check, wall thickness inspection, MTC
API 5L PSL1 / PSL2	Oil, natural gas, oil & gas transmission	≤25 MPa / -30°C to 50°C	Hot-rolled seamless / welded	Oil pipelines, natural gas pipelines	Radiographic testing, ultrasonic testing, MTC
EN 10216-1	Water, gas, steam, chemical liquids	≤20 MPa / -20°C to 400°C	Hot-rolled seamless	Industrial pipelines, general pressure fluid transportation	Dimensional measurement, ultrasonic testing
DIN 2448 / DIN 1629	Water, gas, oil	≤16 MPa / -20°C to 350°C	Hot-rolled seamless	Industrial pipelines, mechanical structures	Dimensional measurement, visual inspection
GB/T 8162	Water, low-pressure oil & gas	≤10 MPa / -20°C to 300°C	Hot-rolled seamless	Municipal water supply/drainage, low-pressure gas pipelines	Dimensional check, wall thickness inspection
GB/T 8163	Water, oil, gas	≤10 MPa / -20°C to 350°C	Hot-rolled seamless / welded	Municipal piping, industrial fluid transportation	Dimensional inspection, ultrasonic testing
GB/T 5310	High-pressure boiler steam	≤25 MPa / 450°C to 500°C	Hot-rolled seamless	High-pressure boiler piping, heat exchangers	Dimensional inspection, NDT, heat treatment records

V. Selection Table for Seamless Carbon Steel Pipes for Industrial Fluid Conveyance

Fluid Type / Application	Common Standards	Pipe Size Range OD (inch / mm)	Wall Thickness Range WT (mm)	Allowable Working Pressure (MPa)	Features / Typical Use
Water, Steam	ASTM A106 Gr.B / GB/T 8162	1/2″ – 24″ (21.3 – 609.6)	2 – 60	≤25	Suitable for high-temperature steam and water transportation; strong pressure resistance
Oil Transportation	ASTM A106 Gr.B / API 5L PSL1	1/2″ – 24″ (21.3 – 609.6)	3 – 50	≤25	Used for crude oil and refined oil pipelines
Natural Gas / Fuel Gas	ASTM A53 Gr.B / API 5L PSL1	1/2″ – 20″ (21.3 – 508)	2 – 40	≤20	Medium- and low-pressure gas transmission; safe and reliable
Chemical Liquids	EN 10216-1 / GB/T 8163	15 – 600 mm	2 – 50	≤20	Chemical plant process piping; optional internal lining or coating for corrosion resistance
High-Temperature & High-Pressure Fluids	ASTM A106 Gr.C / GB/T 5310	1/2″ – 24″ (21.3 – 609.6)	3 – 60	≤25	For boilers, high-temperature hot water, and steam pipelines
Precision Fluids	ASTM A519 / Cold-drawn Seamless	1/4″ – 4″ (6 – 114.3)	1 – 20	≤10	Mechanical hydraulics, pharmaceutical, and food industry fluid transmission

VI. Seamless Carbon Steel Pipe Standards and Chemical Composition Comparison Table

Standard	Steel Grade	C (%)	Mn (%)	P (%)	S (%)	Si (%)
ASTM A106	Gr.B	0.28 max	0.29–0.60	0.035 max	0.035 max	0.10–0.35
ASTM A106	Gr.C	0.30–0.35	0.29–0.60	0.035 max	0.035 max	0.10–0.35
ASTM A53	Gr.B	0.30 max	0.29–1.06	0.035 max	0.035 max	0.10–0.30
API 5L	PSL1 Gr.B	0.28 max	0.30–1.06	0.035 max	0.035 max	0.10–0.30
API 5L	PSL2 X42-X52	0.26–0.28	0.50–1.20	0.025–0.030	0.025–0.030	0.10–0.35
GB/T 8162	Q235	0.22 max	0.30–0.65	0.035 max	0.035 max	0.10–0.35
GB/T 8163	Q235 / Q345	0.22–0.30	0.30–0.70	0.035 max	0.035 max	0.10–0.35
EN 10216-1	P235TR1 / P265TR1	0.17–0.22	0.30–0.65	0.025 max	0.025 max	0.10–0.30

VII. Mechanical Properties Comparison Table for Seamless Carbon Steel Pipes for Industrial Fluid Conveyance

Standard	Steel Grade	Yield Strength σy (MPa)	Tensile Strength σb (MPa)	Elongation δ5 (%)	Impact Toughness KV (J)
ASTM A106	Gr.B	205 min	330–480	30 min	—
ASTM A106	Gr.C	230 min	415–550	25 min	—
ASTM A53	Gr.B	205 min	340–470	25 min	—
API 5L	PSL1 Gr.B	245 min	415–530	25 min	—
API 5L	PSL2 X42	290 min	415–535	23 min	27 min (–20°C)
API 5L	PSL2 X52	355 min	450–585	21 min	27 min (–20°C)
GB/T 8162	Q235	235 min	370–500	26 min	—
GB/T 8163	Q235	235 min	370–500	26 min	—
GB/T 8163	Q345	345 min	470–630	21 min	—
EN 10216-1	P235TR1	235 min	360–510	25 min	—
EN 10216-1	P265TR1	265 min	410–560	23 min	—

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1. Pipe Size Chart (OD, Wall Thickness, Weight) — Common Sizes

Outside Diameter (OD) mm	Outside Diameter (OD) inch	Wall Thickness (mm)	Wall Thickness (inch)	Weight (kg/m)
21.3 mm	1/2″	2.77	0.109″	2.08
26.7 mm	3/4″	2.87	0.113″	2.51
33.4 mm	1″	3.38	0.133″	3.38
42.2 mm	1-1/4″	3.56	0.140″	4.63
48.3 mm	1-1/2″	3.68	0.145″	5.44
60.3 mm	2″	3.91	0.154″	7.77
73.0 mm	2-1/2″	5.16	0.203″	12.7
88.9 mm	3″	5.49	0.216″	17.3
114.3 mm	4″	6.02	0.237″	24.3
141.3 mm	5″	6.55	0.258″	34.5
168.3 mm	6″	7.11	0.280″	45.4
219.1 mm	8″	8.18	0.322″	73.3
273.1 mm	10″	9.27	0.365″	106.0
323.9 mm	12″	9.53	0.375″	129.0
355.6 mm	14″	9.53–12.70	0.375–0.500″	140–185
406.4 mm	16″	9.53–12.70	0.375–0.500″	165–225
457.0 mm	18″	12.70	0.500″	255
508.0 mm	20″	12.70	0.500″	285
610.0 mm	24″	12.70–20.00	0.500–0.787″	350–520

2. Thickness Range (All Standard Specs)

Schedule 10 / 20 / 40 / 80 / 160 / XXS
Thickness range: 2 mm – 50 mm

3. Outside Diameter Range

10.3 mm – 1016 mm
(½” – 40″)

4. Length (Standard)

5.8 m / 6 m / 11.8 m / 12 m
Random Length (RL)
Double Random Length (DRL)
Fixed length available

5. Common Material Grades

适用：ASTM A106 / ASTM A53 / API 5L / ASTM A333 等

ASTM A106 Gr.A / Gr.B / Gr.C
ASTM A53 Gr.A / Gr.B
API 5L Gr.B / X42 / X52 / X60 / X65

Common Standards for Seamless Carbon Steel Pipes

i. American Standards (ASTM / ASME)

Standard	Description	Application / Scope
ASTM A106	Carbon steel seamless pipe for high-temperature service	Conveying steam, water, gas, and high-temperature fluids
ASTM A53	Ordinary carbon steel pipe, including seamless and welded pipes	Water supply, gas transportation, structural piping
ASTM A333	Carbon and low-alloy steel seamless pipe for low-temperature service	Conveying low-temperature liquids and gases
ASME SA106 / SA53	Equivalent to ASTM standards	Boiler, pressure vessel, and piping design

ii. API Standards

Standard	Description	Application / Scope
API 5L	Seamless and welded pipes for oil and gas pipelines	Conveying oil, natural gas, and oil & gas pipeline transportation

iii. European Standards (EN / DIN)

Standard	Description	Application / Scope
EN 10216-1	Seamless carbon steel tubes	General applications, pressure pipelines, and industrial piping
DIN 2448 / DIN 1629	Seamless steel pipes	Water supply, boiler service, and industrial applications

iv. Chinese Standards (GB/YB)

Standard	Description	Application / Scope
GB/T 8162	Seamless steel pipes for fluid transportation	Low-pressure transmission of water, oil, gas, and other fluids
GB/T 8163	Seamless and welded steel pipes for fluid transportation	Municipal water supply and low-pressure gas pipelines
GB/T 5310	Seamless steel tubes for high-pressure boiler service	High-pressure piping for steam boilers and hot-water boilers

Step	Process	Description
1	Raw Material Inspection	Inspect round billet/ingot quality.
2	Heating	Heat billets in a rotary furnace.
3	Piercing	Use a piercing mill to create a hollow shell.
4	Elongation	Elongate and thicken/resize the hollow tube.
5	Hot Rolling	Roll to required diameter and wall thickness.
6	Sizing / Reducing	Final dimension sizing for accuracy.
7	Cooling	Air cooling or controlled cooling.
8	Straightening	Make pipe straight and uniform.
9	Cutting	Cut to required lengths (6m/12m).
10	Heat Treatment (If required)	Normalize or anneal for improved properties.
11	NDT Testing	UT/ET/Hydrostatic testing for defects.
12	Surface Cleaning	Remove oxide scale by shot blasting.
13	Marking & Coating	Apply markings, varnish, black painting or anti-rust oil.
14	Final Inspection & Packing	Inspect, bundle, and prepare for shipment.

Seamless Carbon Steel Pipe Inspection Checklist

1. Appearance and Dimensions Inspection

Inspection Item	Inspection Content	Acceptance Criteria (Value)	Tools / Methods
Appearance Quality	No cracks, folds, laps, dents, scabs, or hard spots on the surface	Not allowed	Visual inspection, flashlight, magnifier
Outside Diameter (OD)	Nominal size deviation (per standard)	±1% or ±0.5 mm (whichever is greater)	Vernier caliper, OD gauge
Wall Thickness (WT)	Nominal wall thickness deviation	-12.5% to +12.5%	Ultrasonic thickness gauge, micrometer
Ovality	Max OD difference / Min OD difference	≤ 0.5%	OD gauge
Straightness	Bending per meter	≤ 1.5 mm/m	Steel ruler, level
Length	Fixed length or double random length	±10 mm	Steel tape

2. Chemical Composition (ASTM A106 Grade B as an example)

Element	Standard Requirement (wt%)
C (Carbon)	≤ 0.30
Mn (Manganese)	0.29 – 1.06
P (Phosphorus)	≤ 0.035
S (Sulfur)	≤ 0.035
Si (Silicon)	≥ 0.10
Cr (Chromium)	≤ 0.40
Cu (Copper)	≤ 0.40
Mo (Molybdenum)	≤ 0.15
Ni (Nickel)	≤ 0.40

3. Mechanical Properties

Item	Requirement	Acceptance Value
Yield Strength	≥ 240 MPa	Not less than 240 MPa
Tensile Strength	≥ 415 MPa	Not less than 415 MPa
Elongation	≥ 30% (standard specimen)	Not less than 30%
Hardness (optional)	HBW ≤ 187	Not more than 187 HBW

4. Flattening Test

Item	Requirement
No cracks on the specimen surface after flattening to the specified distance	Pass
Flattening ratio	Calculated by OD/WT ratio according to the standard table (generally can be flattened up to 60% of the pipe diameter)

5. Flare Test (Optional)

Item	Requirement
Flare angle 37° or 60°	No cracks at the pipe end
Final flare diameter	Expanded to 1.15D–1.2D according to the standard diameter

6. Eddy Current, Ultrasonic Testing (NDT) Non-Destructive Testing

Inspection Item	Acceptance Criteria
UT (Ultrasonic Testing)	Defect echoes ≥ 5% of wall thickness are not allowed
ET (Eddy Current Testing)	Continuous or persistent signal defects are not allowed
RT (Radiographic Testing, optional)	Cracks, slag inclusions, or lack-of-penetration defects are not allowed

7. Hydrostatic Test

Item	Acceptance Criteria
Test Pressure	≥ 60 MPa (6000 psi) or according to the formula P = 2St/D
Holding Time	≥ 5 seconds
Leak Detection	No leakage, wet spots, or rupture allowed

Frequently Asked Questions About Seamless Carbon Steel Pipes for Industrial Fluid Conveyance

i. Why are seamless carbon steel pipes more suitable than welded pipes for industrial fluid transportation?

Answer:
Seamless carbon steel pipes lack welded joints, offering superior structural integrity, higher pressure resistance, and enhanced leak prevention.
Their uniform wall thickness minimizes weak points, making them ideal for high-pressure, long-distance pipelines.
For transporting high-temperature steam, petroleum products, natural gas, and similar fluids, they deliver greater safety and reliability than welded pipes.
Seamless pipes are the preferred choice, particularly in medium-to-high-pressure systems, extended pipelines, and critical industrial projects.

ii. What are the common issues encountered with seamless carbon steel pipes during use?

Answer:
Corrosion: Long-term conveyance of water or chemical liquids can lead to rusting if the pipes lack internal/external anti-corrosion coatings or cathodic protection.
Scaling/Blockage: High impurity levels in water or chemical liquids may cause deposits to form inside pipes, restricting flow.
Leakage Points: Despite high strength, improper installation at welded joints or flange connections may cause water/gas leaks.
Bending/Deformation: Improper transportation or installation can cause pipe bending, reducing fluid conveyance efficiency.

iii. How to select the appropriate standard and grade?

Answer:
Select standards based on fluid type, temperature, pressure, and environmental conditions.
High-temperature, high-pressure steam or hot water → ASTM A106 Gr.B/C, GB/T 5310
Municipal water supply, low-pressure gas → ASTM A53 Gr.B, GB/T 8162
Oil and gas transmission → API 5L PSL1/PSL2
Chemical industry liquids → EN 10216-1 or GB/T 8163
When selecting standards, consider allowable working pressure, temperature range, chemical composition, and mechanical properties.

iv. What precautions should be taken during transportation and installation of seamless carbon steel pipes?

Answer:
During transportation: Avoid collisions or drops between pipes. Secure them using wooden crates or slings.
Storage: Protect against moisture, rain, and prolonged sun exposure. Prevent water accumulation inside or outside the pipes.
Installation: Ensure supports are secure. Maintain horizontal support spacing according to design specifications. Use proper techniques for bends or connections to avoid damaging the pipe walls.
Flanges and joints: Ensure tight alignment to guarantee sealing and prevent leaks.

v. How can service life be extended?

Answer:
Anti-corrosion treatment: Apply coatings, hot-dip galvanizing, or epoxy coatings to internal and external surfaces to extend service life.
Optimize design pressure and flow velocity: Avoid excessive pressure or high flow rates that cause wear.
Conduct regular inspections: Check for pipe corrosion, bending, deposits, and leak points.
Select appropriate material grades: Use high-strength grades like Gr.C or X52 for high-pressure or high-temperature fluids.

vi. How to verify the reliability of pipe quality?

Answer:
Mill Test Certificate: Require suppliers to provide a Mill Test Certificate (MTC) containing information on chemical composition, mechanical properties, dimensional inspection, etc.
Non-Destructive Testing: Opt for ultrasonic or radiographic inspection to ensure no internal defects in the pipes.
Dimensional Tolerance Check: Verify that outer diameter, wall thickness, length, and straightness meet standards.
Brand and Supplier Credentials: Select manufacturers with quality assurance and export experience to mitigate risks.