Pipe and Tube Difference: Everything You Need to Know
In the steel manufacturing sector, steel pipes and steel tubes may appear similar, but they differ significantly in purpose and sizing. Both have hollow, cylindrical shapes, yet their applications and measurement standards are distinct. These differences impact how they are used across various industries.
This blog explores the key pipe and tube difference, covering their dimensions, manufacturing and typical applications. Understanding these distinctions helps industries select the right product for their specific needs.
What is a Pipe?
Steel pipe is a hollow, round section engineered primarily to move products like fluids, gases, slurries, pellets, and powders safely and efficiently. Commercial production dates back to the early 19th century, and today pipe is specified wherever reliable pressure conveyance and durability are required.
In city infrastructure, steel pipes run underground for water and gas distribution. In buildings, they’re often called out as conduit to shield electrical wiring. Thanks to high strength at relatively low weight, pipe also finds its way into bicycle frames and automotive components. You’ll see steel pipes in refrigeration and HVAC, heating and plumbing systems, and in everyday fixtures like flagpoles and street/area light poles.
What is a Tube?
The term tube covers hollow sections in round, square, rectangular, and oval profiles used in pressure equipment, mechanical assemblies, and instrumentation systems.
Steel tubing can be produced from combinations of iron, carbon, manganese, with alloy additions such as vanadium and zirconium. Like pipe, tube is made as seamless or welded. In seamless production, a solid billet is formed into a cylinder, then pierced and elongated to final length and wall. Welded tube starts from a coil/strip that is slit, formed into a round, and edge-welded. From there, it can be cut to length as a round tube or sized into square, rectangular, or oval sections.
Difference between Pipe and Tube Diameter
When placing an order for a tube, dimensions are typically given as outside diameter (OD) and wall thickness. In some cases, buyers specify OD & ID or ID & wall. Note that the ID (inner diameter) is often a calculated value, while wall thickness may be referenced by a gauge number. In many catalogs, lower gauge numbers correspond to heavier walls/larger effective OD. By contrast, pipe is ordered using the NPS (Nominal Pipe Size) system, where you specify the nominal diameter (pipe size) along with the schedule (wall designation). This is a core pipe vs tube difference: tubes are dimensioned by actual OD/ID and wall; pipes use NPS and schedule for flow and pressure service.
Pipe and Tube Manufacturing Process
Pipe vs Tube Tolerance and Application
The core pipe vs tube difference lies in tolerances and end use. Steel pipes are primarily specified for moving liquids and gases, so capacity, pressure rating, and allowable tolerance bands are critical to ensure safe flow and service life.
Steel tubes are typically chosen for structural and mechanical duties. In agriculture, for example, tubes are used to fabricate pivots and frames, where consistent OD/ID, wall thickness, and straightness support load-bearing performance.
Manufacturing routes also separate the two. Tubes are produced to tighter dimensional tolerances and therefore require more extensive process control, testing, and inspection to meet standards and specification limits. Because of the precision and quality checks involved, tube production generally carries higher cost, driven by labor, energy, and material utilization. Pipe construction is typically simpler and more scalable, which helps reduce unit cost for many applications.
Steel Pipe and Tube Difference at a Glance
What is the difference between pipe and tube? To understand this in a better manner, below is a table illustrated to explain the pipe and tube difference:
Parameters | Steel Pipe | Steel Tube |
Dimensions | Pipe dimensions use outside diameter (OD) and wall thickness (WT); these determine inside diameter (ID). Formula: ID = OD − 2 × WT. The ID largely governs the pipe’s flow capacity. | Tube dimensions are stated directly as OD and WT (in inches or millimeters). These values define the tube’s hollow cross-section with emphasis on exact size and fit. |
Wall thickness | The wall is designated by Schedule (e.g., Sch. 40). Two pipes with different NPS (Nominal Pipe Size) but the same Schedule will have different actual walls in inch/mm terms. | Wall is expressed in inches or millimeters; tubing may also use gauge notation, tied to target tolerances and application. |
Types (shapes) | Round only. | Round, square, rectangular, oval. |
Production range | Very broad—large diameters available (up to ~80 in and beyond, depending on mill). | Typically narrower for precision tubing (to ~5 in OD common), with larger sizes available in mechanical/structural tubes. |
Tolerances & strength | Tolerances are defined but more forgiving; strength is usually not the primary sizing driver (flow/pressure is). | Manufactured to strict tolerances (straightness, roundness, wall, surface). Mechanical strength and dimensional accuracy are key acceptance criteria. |
Production process | Often produced to stock on highly automated pipe mills running continuously; global distributor inventories are common. | More processing-intensive with additional sizing and inspection steps; can be longer and more labor-intensive overall. |
Delivery time | Typically shorter due to standardized specs and broad stock. | Generally longer because of tighter tolerances and added QA steps. |
Market price | Lower cost per ton on average than comparable tubes. | Higher cost driven by lower mill throughput per hour and stricter tolerance/inspection requirements. |
Materials | Available in a wide range of materials and grades for pressure service. | Common in carbon steel, low-alloy, stainless, and nickel alloys; mechanical/structural tubes are often carbon steel. |
End connections | Most common: beveled, plain, and threaded (screwed) ends. | Threaded and grooved ends are available for faster on-site assembly; ends may also be plain for fabrication. |
Stellar Alloys: Your Trusted Steel Pipe and Tube Supplier
Understanding the distinctions between steel pipes and tubes is crucial for making the right choice in any industrial application. Consider factors like dimensions, strength, material, and purpose to ensure optimal performance and cost efficiency in your project.
As a leading steel pipe and tube supplier, Stellar Alloys offers a comprehensive range of high-quality steel pipes and tubes, trusted by industries for reliable products and expert service.
Frequently Asked Questions About Pipe and Tube
Steel pipes are primarily used for transporting fluids and gases in industries like construction, oil and gas, plumbing, and water supply. They are also used structurally in automotive parts, refrigeration, heating, scaffolding, and street lighting.
Steel pipes are generally stronger, more durable, and better suited for high-pressure and high-temperature applications than PVC. While PVC is corrosion-resistant and cost-effective in the short term, steel pipes offer longer service life and higher strength.
Steel pipes are measured by inside diameter (ID) and are primarily intended for transporting fluids or gases. Steel tubes are measured by outside diameter (OD), available in multiple shapes (round, square, rectangular), and used mainly for structural and mechanical applications requiring precision.
Steel tubes are commonly available in standard lengths of 6 meters (approximately 20 feet) but can vary depending on manufacturing and customer requirements.
The three main types are:
- Carbon Steel Pipe: Most common, used for general applications.
- Stainless Steel Pipe: Corrosion-resistant, used in chemical and food industries.
- Galvanized Steel Pipe: Coated with zinc for corrosion protection, used in outdoor and water systems.
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