This page provides standard seamless pipe dimensions for industrial, mechanical, and pressure applications. You can review common seamless steel pipe sizes, including outside diameter (OD), wall thickness, schedule reference, and length range.
For complete material grades, production capability, and export support, please visit our seamless steel pipe product page for more commercial information.
Standard Seamless Pipe Dimensions Overview
Seamless pipes are widely used in oil and gas, high-pressure transmission, boilers, hydraulic systems, and mechanical processing industries. Compared with welded pipes, seamless steel pipes are commonly selected for applications requiring higher pressure resistance and tighter tolerance control.
This page mainly focuses on seamless pipe dimensions and size reference. If you need broader pipe specification comparison, you may also review our steel pipe dimensions resource page.
Pipe Schedule Chart unit in mm as below, view here for Pipe Schedule Chart in inch.
Seamless steel pipe sizes are defined by outer diameter (OD), wall thickness (WT), and pipe schedule (SCH).
Standard ranges include:
OD: 1/2" to 36" (21.3 mm – 914.4 mm)
Wall Thickness: 2.11 mm to 60 mm
Schedules: SCH10, SCH20, SCH40, SCH80, SCH160, STD, XS, XXS
| DN | NPS (inch) | Outside Diameter (mm) | Schedule 5S | Schedule 10S | Schedule 20S | Schedule 40S | Schedule 80S | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| WT (mm) | Weight (kg/m) | WT (mm) | Weight (kg/m) | WT (mm) | Weight (kg/m) | WT (mm) | Weight (kg/m) | WT (mm) | Weight (kg/m) | |||
| 3 | 1/8" | 10.3 | 1.2 | 0.2 | 1.24 | 0.28 | 1.5 | 0.33 | 1.73 | 0.37 | 2.41 | 0.47 |
| 6 | 1/4" | 13.7 | 1.2 | 0.37 | 1.65 | 0.49 | 2 | 0.58 | 2.24 | 0.63 | 3.02 | 0.8 |
| 10 | 3/8" | 17.1 | 1.2 | 0.47 | 1.65 | 0.63 | 2 | 0.74 | 2.31 | 0.84 | 3.2 | 1.1 |
| 15 | 1/2" | 21.3 | 1.65 | 0.8 | 2.11 | 1 | 2.3 | 1.07 | 2.77 | 1.27 | 3.73 | 1.62 |
| 20 | 3/4" | 26.7 | 1.65 | 1.03 | 2.11 | 1.28 | 2.55 | 1.52 | 2.87 | 1.69 | 3.91 | 2.2 |
| 25 | 1" | 33.4 | 1.65 | 1.3 | 2.77 | 2.09 | 2.55 | 1.94 | 3.38 | 2.5 | 4.55 | 3.24 |
| 32 | 1-1/4" | 42.2 | 1.65 | 1.65 | 2.77 | 2.7 | 3 | 2.9 | 3.56 | 3.39 | 4.85 | 4.47 |
| 40 | 1-1/2" | 48.3 | 1.65 | 1.91 | 2.77 | 3.11 | 3 | 3.55 | 3.68 | 4.05 | 5.08 | 5.41 |
| 50 | 2" | 60.3 | 1.65 | 2.4 | 2.77 | 3.93 | 3 | 4.24 | 3.91 | 5.44 | 5.54 | 7.48 |
| 65 | 2-1/2" | 73 | 2.11 | 3.69 | 3.05 | 5.26 | 4 | 6.81 | 5.16 | 8.63 | 7.01 | 11.41 |
| 80 | 3" | 88.9 | 2.11 | 4.51 | 3.05 | 6.45 | 4 | 8.37 | 5.49 | 11.29 | 7.62 | 15.27 |
| 100 | 4" | 114.3 | 2.11 | 5.84 | 3.05 | 8.36 | 4.5 | 12.18 | 6.02 | 16.07 | 8.56 | 22.32 |
| 125 | 5" | 141.3 | 2.77 | 9.47 | 3.4 | 11.57 | 5 | 16.8 | 6.55 | 21.8 | 9.53 | 30.97 |
| 150 | 6" | 168.3 | 2.77 | 11.32 | 3.4 | 13.84 | 6.35 | 25.36 | 7.11 | 28.26 | 10.97 | 42.56 |
| 200 | 8" | 219.1 | 2.77 | 14.79 | 3.76 | 19.96 | 6.35 | 33.31 | 8.18 | 42.55 | 12.7 | 64.64 |
| 250 | 10" | 273.1 | 3.4 | 22.63 | 4.19 | 27.78 | 6.35 | 41.77 | 9.27 | 60.31 | 12.7 | 96.01 |
| 300 | 12" | 323.8 | 3.96 | 31.25 | 4.57 | 36 | 6.35 | 49.7 | 9.53 | 73.88 | 12.7 | 132.05 |
The dimensions above are provided for general reference. Actual seamless pipe sizes, tolerance, and schedule availability may vary according to standard system and mill production range.
The dimensions of seamless steel pipe are primarily determined by three parameters: outer diameter, wall thickness, and length.
Outer Diameter Range
Small Diameter Seamless Steel Pipe: The outer diameter is typically 6mm to 89mm.
Medium Diameter Seamless Steel Pipe: The outer diameter is typically 89mm to 219mm.
Large Diameter Seamless Steel Pipe: The outer diameter is typically 219mm or greater.
Wall Thickness Range
Conventional wall thicknesses are categorized into three types:
SCH5S to SCH160 Standard Wall Thickness Series
XS/XXS Thickened Series
ST Special Thin Wall Series
Thin-Wall Seamless Steel Pipe: The wall thickness is typically 1mm to 6mm.
Thick-Walled Seamless Steel Pipe: Wall thickness is typically 6mm or thicker, with some reaching 50mm or thicker.
Length Specifications
Fixed Lengths: Commonly available in three standard lengths: 6m, 9m, and 12m.
Multiple Lengths: Specific multiples of length produced to order.
Special Lengths: Determined based on production conditions, generally ranging from 4 to 12m.
Common Specifications
Small Diameters: Examples include Φ25×2.5, Φ32×3, and Φ57×3.5.
Medium Diameters: Examples include Φ89×4, Φ108×4.5, and Φ159×6.
Large Diameters: Examples include Φ219×8, Φ273×10, and Φ325×12.
Seamless Steel Pipe Size Overview Table
Below is an overview of common seamless steel pipe dimensions, including outer diameter (OD) and wall thickness (WT). For a complete seamless dteel pipe OD WT chart, please refer to the detailed table below.
| Pipe Type | Outer Diameter (OD) | Wall Thickness (WT) | Length | Typical Examples |
|---|---|---|---|---|
| Small Diameter | 6–89 mm | 1–6 mm | 6–12 m | Φ25×2.5, Φ32×3 |
| Medium Diameter | 89–219 mm | 5–16 mm | 6–12 m | Φ89×4, Φ108×4.5 |
| Large Diameter | 219 mm+ | 6–50+ mm | 6–12 m | Φ219×8, Φ273×10 |
If you need project-specific dimensions, you can submit your request through our pipe quotation page for confirmation.
Seamless pipe dimensions are generally defined by outside diameter, wall thickness, and schedule system. Different industries may follow different standards depending on application and pressure requirements.
When selecting seamless steel pipes, buyers should confirm:
OD and wall thickness
Schedule system
Pressure requirement
Material grade
Length requirement
Applicable standard
For structural or general-purpose welded applications, you may also compare dimensions with our ERW steel tube products.
Pipe Size Reference by Application
Typical size ranges and standards for different seamless pipe applications are summarized below.
Carbon Steel Pipe Size (API & ASTM)
| Standard | Size Range (NPS) | OD Range (mm) | Schedule Range | Typical Application |
|---|---|---|---|---|
| API 5L | 2" – 24" | 60.3 – 610 mm | SCH40 – SCH160 | Oil & gas transmission |
| ASTM A106 | 1/8" – 26" | 10.3 – 660 mm | SCH20 – SCH160 | High-temperature service |
| ASTM A53 | 1/8" – 26" | 10.3 – 660 mm | SCH20 – SCH80 | Structural & low-pressure piping |
Boiler Tube Size Range
| Parameter | Value | Standard | Notes |
|---|---|---|---|
| Outer Diameter (OD) | 10.2 – 139.7 mm | ASTM A192 / GB5310 | ≥26.9 mm typically hot rolled |
| Wall Thickness (WT) | 0.5 – 16 mm | ASTM A210 | Designed for high pressure |
| Length | Up to 12 m | — | Fixed or random length |
| Application | — | — | Boilers, superheaters |
Precision Tube Size Range
| Specification Parameter | Dimension Range / Value | Applicable Standard | Key Technical Feature |
|---|---|---|---|
| Outer Diameter (OD) | 10 – 120 mm | EN 10305-1 | High dimensional accuracy for precision applications |
| Wall Thickness (WT) | 0.5 – 5 mm | DIN 2391 | Tight tolerance control ensures consistent performance |
| Length | 4 – 8 m | — | Cold drawn process ensures smooth surface finish |
| Dimensional Tolerance | ±0.1 mm | — | Suitable for precision machining and hydraulic systems |
Hydraulic Tube Size Range
| Specification Item | Specification Value / Range | Standard Reference | Technical Description |
|---|---|---|---|
| Outer Diameter (OD) | 4 – 130 mm | EN 10305-4 | Optimized for hydraulic and precision tube systems |
| Material Grade | E235 / E355 | DIN 2391 | High strength with excellent machinability performance |
| Delivery Condition | NBK (Normalized + Phosphated) | — | Improved surface protection and corrosion resistance |
| Application Field | Hydraulic & Pneumatic Systems | — | Suitable for high-pressure fluid transmission lines |
1. Rolling Process Parameters
The piercing mill's rolling angle and rolling speed directly affect the pipe's outer diameter accuracy. The reduction and number of rolling passes during cold rolling determine wall thickness variation. Fluctuations in process parameters can also lead to dimensional deviations.
2. Raw Material Quality
The diameter, roundness, and material uniformity of the tube billet are all transferred to the finished product. If the tube billet exhibits ovality, it can easily result in an out-of-round outer diameter of the steel pipe.
3. Temperature Control
Excessively high or uneven heating temperatures can cause inconsistent tube billet deformation, and differences in cooling rates can cause dimensional shrinkage deviations, especially in high-precision cold-drawn tubes.
4. Equipment Accuracy
Mechanical clearances and die wear in equipment such as rolling mills and sizing mills directly affect the consistency of pipe diameter and wall thickness. Older equipment can exacerbate dimensional fluctuations.
5. Subsequent Processing
Improper operation in processes such as straightening and cutting can lead to deviations in pipe straightness or length.
Q1: What are standard seamless pipe dimensions?
A1: Standard seamless pipe dimensions include outside diameter, wall thickness, schedule, and length range.
Q2: What is the difference between seamless and welded pipe dimensions?
A2: Seamless pipes usually provide higher pressure resistance and tighter tolerance control compared with welded pipes.
Q3: Are seamless pipe dimensions based on OD or ID?
A3: Most seamless pipe dimensions are based on outside diameter (OD) and wall thickness.
Q4: Can seamless pipes be customized?
A4: Yes. Length, thickness, and processing can often be customized depending on order requirements.
Q5: Are all seamless pipe sizes available in stock?
A5: Availability depends on mill production schedule and inventory conditions.
Looking for seamless pipe quotation based on exact dimensions? Send us your required OD, thickness, schedule, grade, and quantity.
For faster response, please submit your inquiry through our seamless steel pipe contact page.
