- Key Takeaways
- Understanding Standard Metal Tube Sizes
- Key Differences: Tubing vs. Piping
- International Sizing Standards
- Common Material Specifications
- How to Choose Metal Tube Sizes
- Beyond the Standard Chart
- Conclusion
- Frequently Asked Questions
Key Takeaways
- Standard metal tube sizes specify outside diameter, wall thickness, and length to be interchangeable in fabrication and construction. Measure outside diameter with a caliper and note dimensions in millimeters for global consistency.
- Wall thickness dictates strength, pressure rating, and weight. Select thickness for your calculated loads and safety factors and confirm in mm or gauge wall thickness prior to order.
- Inside diameter controls flow and internal clearance and is obtained by subtracting twice the wall thickness from the outside diameter. Apply this rule of thumb when engineering fluid systems or designing fittings.
- Follow standards (ASTM, EN, JIS etc.) to meet tolerances, dimensions, and material requirements at your project location or compliance needs, and download dimension charts for reference.
- Match material choice to application needs. Compare steel, aluminum, and copper properties. Then check availability, price, and lead time to balance performance with budget.
- For nonstandard requirements, ask for custom specifications such as outer diameter, wall thickness, length, material, and manufacturing process. Verify supplier capabilities, minimum quantities, and lead times prior to ordering.
Standard metal tube sizes are ranges of outer diameter and wall thickness defined by common industry tables and standards. Sizes depend on material, country, and usage and range from a few millimeters to hundreds of millimeters in diameter with walls from sub-millimeter to tens of millimeters thick.
Pipes and structural tubing have nominal sizes and actual measurements. The meat discusses common standards, how to measure, and selection tips.
Understanding Standard Metal Tube Sizes
Standard metal tube sizes are a collection of outside diameter (OD), wall thickness, and length dimensions that parts mate and systems perform. Standardization is important as it ensures interoperability in fabrication, construction, and manufacturing and relates to specifications from organizations like ASME B36.10 and B36.19.
Tube sizing ties to ordering basics: shape, dimensions, thickness, and weight, along with manufacturer capabilities that can change the final product.
1. Outside Diameter
OD (outside diameter) is the most common way to refer to metal tubes. It determines how tubes mate with connectors, fittings, and structural components and frequently determines the nominal pipe size (NPS) in conjunction with pipe schedules. Measure OD with a caliper or micrometer to be safe. Tape measures can be deceiving on small diameters.
Typical ODs are 6.35 mm (1/4″), 12.7 mm (1/2″), 21.3 mm (3/4″), 25.4 mm (1″), 33.4 mm (1-1/4″), 42.2 mm (1-1/2″), 48.3 mm (1-7/8″) and 60.3 mm (2-3/8″) with bigger sizes in trade ranges. Various standards and materials have slightly different nominal numbers. Refer to ASME or EN tables for the exact OD to NPS mapping.
OD selection influences tooling, connection technique, and design composition. When engineering, verify the source’s ability to manufacture the desired OD in necessary tolerances, as not every mill can offer every size or alloy.
2. Wall Thickness
Wall thickness is an important measure that directly impacts strength, pressure rating, and weight. It is measured in either millimeters, inches, or gauge numbers. Thicker walls provide greater load capacity, but add weight and cost, while thinner walls conserve metal but reduce pressure capability.
Choose wall thickness to correspond with load and pressure requirements. For steel tubing, typical sizes are Sch 40 and Sch 80, with historical standards being WGT (weight type). They include typical thicknesses for each OD. Check ASME B36 steel standards.
Typical wall thicknesses are 1.2 mm, 2.0 mm, 3.0 mm, 4.5 mm, and 6.35 mm in gauges such as 18 gauge, which is approximately 1.22 mm, and 14 gauge, which is approximately 1.63 mm.
3. Inside Diameter
Inside diameter (ID) equals outer diameter (OD) minus two times the wall thickness and defines the flow area for fluids and gases. ID is important for flow rates, pressure drop, and anything that fits inside the tube.
Calculate ID quickly: ID equals OD minus two times wall thickness. Remember, nominal pipe sizes are unintuitive. NPS and schedule specify wall thickness, not ID, directly.
Be sure to check ID when designing systems that need an exact internal space. Always request specific size and tolerance charts from your suppliers.
4. Lengths
Single random, double random, and cut-to-length or fixed lengths are the standard tube lengths. One note is that suppliers might stock tubes by the meter or by the foot. It just depends on countries, and providing cut-to-length can minimize waste onsite.
Standard lengths expedite installation and reduce cost. Custom lengths fit unique projects. Know your standard metal tube sizes.
5. Tolerances
Tolerances are permissible variations in measurements during production and they impact fit and strength. Tighter tolerances are great for precision parts and they’re more expensive.
Standards like ASTM, EN, and JIS specify tolerance levels. Check tolerance charts for serious engineering. Keep in mind, manufacturer capability can change attainable tolerances, so verify prior to final spec.
Key Differences: Tubing vs. Piping
Tubing and piping may appear similar, yet they serve distinct functions and follow different sizing conventions. Understanding these differences is essential for interpreting standard steel tubing size charts, particularly when working with rectangular steel tubing and its applications in piping systems.
Measurement and size identification
Tubing is specified by its precise outer diameter (OD) and wall thickness, usually in millimeters (e.g., 25.4 mm OD with 1.5 mm wall). This makes it easy to mate fittings and to engineer systems that rely on precise dimensional control.
Piping uses NPS and schedule number, with NPS being a name that does not precisely equal pipe OD. For example, a 25 mm NPS (1-inch NPS) pipe comes with an OD around 33.4 mm. That mismatch is important when you require exact joins or when converting from tube to pipe material or vice versa.
Wall thickness and tolerances
Wall thickness for pipe is categorized by schedule (Schedule 40, Schedule 80, etc.), which clusters thickness ranges according to internal pressure capacity. Tubing manufacturers control wall thickness much more tightly.
Tolerances are smaller and consistent across runs. In larger ODs, this tighter tolerance can be the difference between a part that fits and one that doesn’t. Tighter tolerance and uniform wall thickness mean tubing is better where precise flow cross-section or mechanical fit count.
Shape, finish, and manufacturing standards
Pipes are almost always round. Tubes can be round, square, rectangular, or custom, so tube selection enables structural and design applications beyond basic fluid flow.
Pipe production is based on standardized nominal outside diameter tables and schedules. Tube manufacturing emphasizes accuracy in outside diameter and controlled wall thickness and may involve smoother internal or external finishes. This tighter control and finish quality usually translate into higher material cost for tubing compared to pipe.
Applications, industries, and cost
Tubing shows up in aerospace, pharmaceutical, food, and precision mechanical assemblies where dimension, surface finish, and smooth flow are a must. Piping reigns in oil and gas, chemical plants, power plants, and building services.
Some industries use both: a refinery may use pipe for main flow lines and tubing for instrumentation or heat exchangers. Due to tighter tolerances and finishing, tubing is typically more expensive than pipe.
A key difference between tubing and piping is a summary chart of outer diameter, wall thickness, nominal pipe size, schedule, typical uses, and cost that helps clarify selection for design and procurement.
International Sizing Standards
International size standards specify nominal sizes, tolerances, and test requirements for rectangular steel tubing and other types, ensuring they fit and perform across borders. By consulting the appropriate steel tubing standard for a project based on location, application, and regulatory requirements, businesses can avoid ordering mistakes and guarantee conformity with material and test specifications.
ASTM Standards
ASTM rules North American steel tubing and pipe sizes and is referenced for structural and mechanical applications. Among the key specifications are ASTM A500 for cold-formed welded and seamless structural tubing and ASTM A513 for mechanical tubular sections used in machinery, each specifying rectangular steel tubing sizes, wall thicknesses, and allowed grades. Additionally, the steel tube suppliers stock steel tubing that meets these standards, ensuring a wide range of products is available for various projects.
ASTM documents further cover testing procedures like tensile and flattening tests and connect to pipe tables such as ASME B36.10M and B36.19M for schedules. Use these printable ASTM dimension charts for fast on-site checks. They map NPS to actual outside diameters and indicate common wall thicknesses by schedule, which is crucial for obtaining the right specifications for your project.
ASTM sizing typically references NPS, which links to ISO 6708 and DN equivalents. Many ASTM sizes have a one-to-one correlation with DN despite inch-based names. Remember that schedules and wall thickness are different and can influence fit-up on international projects.
ASTM is required when sourcing material in North America or from a supplier who uses U.S. Practice. For precise requirements, consider consulting the rectangular tube supplier for available steel tube specifications and guidance on the correct tubing for your needs.
EN Standards
EN standards define the tube sizes, tolerances and structural use across Europe. EN 10210 hot finished structural hollow sections and EN 10219 cold formed welded hollow sections cover dimensional tolerances as well as allowed steel grades and delivery conditions in metric units.
EN uses DN as the generic size and usually provides both metric and imperial to facilitate cross-border work. Verify outside diameter, wall thickness and tolerances in EN tables because it may not be the same as ASTM or JIS exactly. Check EN compliance when specifying for European projects and see harmonized standards and CE marking rules if relevant.
JIS Standards
JIS is the Japanese Industrial Standard and is in metric units with its own dimension tables. JIS G3444 and JIS G3466 are common for square, rectangular, and circular structural tubes, and they specify sizes, wall thicknesses, and testing rules.
JIS sizes may correspond with DN sizes but can vary in tolerance and schedule of walls. Refer to JIS charts when purchasing from Japanese mills or importing components.
Refer to JIS tables with ISO 6708 mappings when aligning NPS and DN equivalents to prevent ordering mismatches.
Common Material Specifications
Metal tubes are manufactured from various materials, each having its own unique properties that make it ideal for specific applications. Align the material spec with needs such as strength, corrosion resistance, weight, thermal conductance, and machinability.
Material grade charts should be reviewed prior to ordering to verify that material grades are appropriate for the service environment, pressure, temperature, and regulatory limits.
Carbon steel is common for structural and pressure work. Specs such as ASTM A513, A1085, and A519 describe it by yield, tensile, and elongation figures. It is frequently specified along with necessary surface finish and weldability characteristics.
Stainless and alloy steels offer higher corrosion resistance and strength. Shared grades and heat-treatment specifications are listed on grade charts. They are used where exposure or hygiene are a factor.
Aluminum alloys are lightweight and corrosion resistant. Alloys 6061 and 6063 have temper and allowable stresses, making them handy in aircraft and structural skeletons.
Copper and copper alloys are chosen for thermal conductivity and ease of joining. Types K, L, and M are indicated to have wall thickness and pressure ratings and sizes in nominal diameters.
Special or high-performance alloys are selected for elevated temperature or chemical service. Specs point to other standards and tests.
Steel Tubing
Steel tubing is the most popular group for structural, mechanical, and pressure applications. ASTM A513 specifies numerous welded and drawn carbon steel tubes for mechanical purposes, while A519 outlines carbon and alloy steel seamless tubing for high-temperature service. A1085 covers welded structural tubing, which is essential for various projects. Mechanical properties, such as yield, tensile, and elongation, are crucial when selecting a grade for load-bearing components, especially when considering the rectangular steel tubing sizes needed for specific applications.
Forms available include seamless, welded, and DOM (drawn over mandrel). Sizes vary widely, with outer diameters ranging from 1/2 inch to 12 inches or more, and wall thicknesses ranging from 0.065 inch to 1/2 inch and beyond. The steel tubing options cover a range of applications, ensuring that you can find the right specification for your project needs.
Forms available: seamless, welded and DOM (drawn over mandrel). Sizes vary: outer diameters range from 1/2 inch to 12 inches or more and wall thicknesses range from 0.065 inch to 1/2 inch and beyond.
Some specifications call for Type 2 steels, which offer better corrosion resistance and higher strength where necessary. For those looking to customize their tubing, a custom tubing option is available, allowing customers to meet specific requirements. This is particularly important for businesses needing precise dimensions.
In summary, understanding the mechanical properties and available rectangular tube sizes is crucial for selecting the right steel tubing for your applications. With a wide range of products available, including seamless and welded options, you can ensure that your project meets the highest standards of quality and performance.
OD (in) | Wall (in) | Common Grade |
|---|---|---|
1/2 | 0.065 | A513 ERW |
2 | 0.120 | A519 C |
8 | 0.250 | A1085 HSS |
Aluminum Tubing
Aluminum tubing provides low weight and corrosion resistance for aerospace, transport, and building facades. Alloys 6061 (structural) and 6063 (architectural, anodizing) are common and are listed with temper and mechanical limits in alloy charts.
Tubes come round, square, and rectangular and are used where reduced mass or good finish is necessary. Standard aluminum tube sizes feature typical outer diameters ranging from approximately 6 mm to 200 mm, accompanied by wall thicknesses spanning between 0.5 mm and 6 mm, contingent upon the specific shape and intended function.
Choice should be based on yield and ultimate strength from the alloy chart in addition to allowable deflection for structural applications.
Shape | Typical Sizes (mm) | Wall (mm) |
|---|---|---|
Round | 10–100 | 0.8–6.0 |
Square | 20 by 20 to 100 by 100 | 1.0 to 5.0 |
Rectangular | 30 by 20 to 200 by 100 | 1.2 to 6.0 |
Copper Tubing
Copper tubing is used for plumbing, HVAC, and refrigeration due to high thermal conductivity and corrosion resistance in many waters. Types K, L, and M vary in thickness and pressure ratings, with K being the thickest for buried or higher-pressure lines and M being thinner for low-pressure domestic distribution.
Copper is sized by nominal diameter and available in coils or straight lengths. Application requirements (water, refrigerant, gas) versus type and pressure tables.
Nominal (in) | Type K wall (in) | Type L wall (in) | Common Use |
|---|---|---|---|
1/4 | 0.035 | ||
0.028 | Refrigeration | ||
1/2 | 0.049 | 0.035 | Domestic water |
1 | 0.109 | 0.083 | Service mains |
How to Choose Metal Tube Sizes
Selecting tube sizes begins with a focused vision of what the tube needs to accomplish and the conditions it will encounter. Think function, load, flow and fabrication limits before choosing outer diameter, wall thickness, shape or material.
Here are the main considerations when choosing tube sizes:
- Application function: structural, fluid, or decorative
- Shape: Round, square, or rectangular and its effect on load.
- Dimensions: OD (outer diameter), ID, and length
- Wall thickness: in millimeters (or gauge)
- Material: steel grade, alloy, corrosion resistance
- Weight and density: calculated per shape and material
- Manufacturer capabilities: sizing and fabrication limits
- Cost, stock levels, lead time, and shipping
Application Needs
Determine the tube’s role initially—support a beam, transport fluid, or create a façade. That decision drives almost every other choice.
Environmental risks matter: corrosion, chemicals, high or low temperatures, and UV exposure change material choice. Select shape for design and load: round tubes resist torsion and are common for fluid lines; square or rectangular tubes suit frames where flat surfaces help join parts.
List every requirement: max span, live and dead loads, pressure, required finish, weldability, and any regulatory limits. Remember four main tube specs: shape, dimensions, thickness, and weight. Each affects strength, machinability, and formability.
Consult local norms and standard charts. A typical entry might read OD 50.8 mm (2 in), wall 12.7 mm (0.5 in), length 6.1 m (20 ft).
Load Capacity
Determine anticipated loads, pressures, and stresses to select a safe tube size. Apply section modulus, moment of inertia, and pressure-area formulas for the probable load scenarios.
Look up steel grade yield strength, including a safety margin. Wall thickness and material grade determine the tube’s capacity to handle heavy or dynamic loads. Thicker walls increase stiffness and weight.
Use engineering tables or software to find minimum outside diameter and wall thickness to resist bending, buckling, or internal pressure. Determine the yield strength required and select a safety factor for critical structures.
If in doubt, opt for a higher grade or thicker wall and check with a structural engineer. Remember weight formulas: round tubing weight equals 3.69 multiplied by the outside diameter minus wall thickness multiplied by wall thickness, square equals 4.704 multiplied by outside diameter multiplied by wall thickness multiplied by wall thickness, rectangular equals 4.704 multiplied by the length plus the short side divided by two minus wall thickness multiplied by wall thickness.
Note density references such as 0.289 pounds per cubic inch (approximately 7.99 grams per cubic centimeter) for quick checks.
Cost and Availability
Check local and online suppliers for price and stock. Standard sizes typically cost less and ship faster than custom sized materials.
Check lead times and minimum order quantities. Check to see if your fabricator can bend, cut, or weld your selected tube. Fabrication ability differs by manufacturer and can limit available sizes.
Consider shipping weight and apply the weight formulas above and metric conversions to calculate approximate freight and handling charges.
Weigh performance versus budget. When possible, select a standard tube size that satisfies specifications instead of a custom size that increases cost and delay.
Beyond the Standard Chart
Standard pipe and tube charts address common ODs, nominal sizes and wall schedules, but many projects fall outside those ranges. Some designs need odd diameters, thicker walls for high pressure, exotic alloys for corrosion or shaped sections that a standard chart doesn’t list. When out-of-the-box solutions can’t satisfy performance or compliance requirements, bespoke efforts are required.
Below are the takeaways designers and procurement teams should consider when venturing past standard chart sizes.
Customization
Identify OD, wall thickness, length, and material up front. These four items establish the parameters of any custom order and cut down on back and forth. Detail drawings with tolerances, weld locations, end preparations, and any required heat treatments or inspections help your maker meet your design intent.
Custom tubes may be non-round, oval, or rectangular in shape and may be made in special alloys or clad constructions for corrosion or temperature service. Finish choices matter. Polished, annealed, coated, or bare will change lead time and cost.
Create a checklist before contacting suppliers: dimensions, mechanical properties, environmental loads, inspection needs, applicable codes, and acceptance tests. Engineers should check with manufacturers for feasibility and testing requirements because safety and performance of non-standard pipes may not always be well established.
Manufacturing Impact
Alternative manufacturing processes alter tube characteristics and cost. Seamless, welded, and cold-drawn provide different strengths, tolerances, and surface finishes. Seamless may fit high pressure, welded is typically cheaper for larger sizes, and cold drawn reduces tolerances.
Others enable you to achieve the higher yield strength or tighter dimensional control required for precision assemblies or harsh service. Manufacturing decisions impact permissible wall thicknesses and minimum bend radii, which connects back to design for manufacturability.
Go through process capabilities and typical tolerances with suppliers to match final use and to understand inspection regimes and testing needs.
Sourcing Reality
Availability depends on supplier stock, local demand, and ongoing material creation that broadens choices such as lighter or more rust-resistant metals. Verify lead times and minimum order quantities upfront.
Custom orders can add weeks or months and might need batch testing or special certifications. Establish connections to dependable distributors who can offer technical assistance and maintain backup suppliers on file to prevent schedule risk.
Think regulatory controls in oil and gas. Non-standard pipes require additional paperwork, third-party inspection or approval. Cost and complexity increase as you customize, but custom tailored pipes can achieve performance or design benefits simply not possible with standard stock.
Conclusion
Standard tube sizes provide a transparent foundation to the majority of constructions and fixes. Metric outer diameter and wall numbers dovetail with common wall types, for example, thin-wall for frames and thick-wall for load components. For instance, a 25 mm outer diameter tube with a 2 mm wall is suitable for a bike rack. A 50 mm outer diameter tube with a 6 mm wall is ideal for a gate post. Match material to use: steel for strength, aluminum for light weight, and stainless for rust resistance.
Utilize the above size chart and selection guide to verify fit, strength, and price. Want an instant fit for your work? Send your part load, length, and environment and receive size options and material selections.
Frequently Asked Questions
What are the most common standard metal tube sizes?
Typical tubing sizes, including rectangular steel tubing, vary from approximately 6 mm to 114 mm OD for general purposes. There are larger sizes available, and standard charts from ISO, EN, and ASTM provide exact specifications for each size and application.
How is tubing different from piping?
Tubing, particularly structural steel tubing, is sized by outer diameter and wall thickness to ensure a precise fit and strength. For projects requiring specific dimensions, rectangular steel tubing sizes are essential, while piping is typically sized by nominal bore for fluid conveyance.
Which international standards govern tube sizes?
Main standards are ISO (international), EN/DIN (European/German), and ASTM/ASME (U.S.), which include specifications for structural steel tubing. Each sets dimensions, tolerances, and testing. Always double-check what standard you need for your industry and location.
What materials and specifications should I consider?
Common metals include stainless steel, carbon steel, copper, and aluminum. When considering corrosion resistance and strength, it’s essential to match material specifications, like ASTM A269 for stainless steel tubing, to the environment and load.
How do I choose the right tube size quickly?
To ensure the correct match function for flow or structural load, consult the structural steel tubing specifications, including OD and wall thickness tables for strength and fit, while verifying pressure, temperature, and material compatibility.
Can I substitute pipe for tubing or vice versa?
Different sizing conventions, tolerances, and pressure ratings can cause mismatches in steel tubing. For safety and performance, verify engineering compatibility before swapping, adhering to appropriate specifications.
