Stainless Steel Pipe Size Chart in mm and Inches

Use This Stainless Steel Pipe Size Chart To Compare Common Pipe Sizes, Nominal Pipe Size (NPS), Nominal Bore (NB), Outside Diameter (OD), Inside Diameter (ID), Wall Thickness And Schedule In Millimetres And Inches.

A 2-Inch Stainless Steel Pipe Has A Standard Outside Diameter Of 60.3 Mm (2.375 Inches). Its Inside Diameter Depends On The Selected Wall Thickness Or Schedule.

For Final Selection, Confirm The Stainless Steel Grade, Pipe Type, Dimensional Standard, Schedule, Pressure Design, Operating Temperature, Quantity And Required Length.

Stainless steel pipe size is normally identified using nominal pipe size (NPS) or nominal bore (NB), not by the actual inside diameter. The outside diameter is standardized for each nominal size, while the inside diameter changes according to wall thickness or schedule.

The values above are common reference dimensions. Always check the complete size, schedule, material specification and applicable standard before ordering.

A stainless steel pipe size chart is a dimensional reference showing how pipe sizes are identified and measured. It may include nominal pipe size (NPS), nominal bore (NB), nominal diameter (DN), outside diameter (OD), inside diameter (ID), wall thickness, schedule and nominal weight.

Nominal size is a standardized designation and should not be treated as the exact measured outside or inside diameter. For example, a 2-inch pipe has a standard OD of 60.3 mm, rather than 50.8 mm.

The correct chart helps engineers, fabricators, contractors, procurement teams and buyers compare pipe dimensions, check fitting compatibility and prepare technical purchase specifications.

The table below shows common stainless steel pipe nominal sizes, NB or DN designations and standard outside diameters. The OD remains standardized for a nominal size, while the ID changes with wall thickness.

This table provides nominal sizes and standard outside diameters. It does not provide a single inside diameter for each size because the ID depends on the selected schedule or wall thickness.

NB means nominal bore, OD means outside diameter and ID means inside diameter. These terms describe different aspects of pipe identification and measurement.

• NB: A nominal designation used to identify pipe size.
• DN: A nominal diameter designation commonly used in metric specifications.
• OD: The actual outside diameter of the pipe.
• ID: The internal opening available for fluid flow.

The nominal ID can be calculated using:

ID = OD − (2 × wall thickness)

The calculated ID uses nominal OD and nominal wall thickness. Actual measured dimensions may vary within the tolerances allowed by the applicable product and dimensional standards.

A stainless steel pipe diameter chart helps identify the actual outside diameter corresponding to a nominal pipe size. This is particularly useful when checking pipe compatibility with fittings, valves, flanges, equipment and existing piping.

Pipe schedule identifies a standardized wall-thickness series. For a given nominal pipe size, a heavier schedule generally has a thicker wall and a smaller internal diameter. The standard outside diameter normally remains the same for that nominal size.

Common stainless steel schedule designations include 5S, 10S, 40S and 80S. Exact values depend on nominal size and the applicable dimensional standard.

Stainless steel pipe dimensions are commonly checked against ASME B36.19M, which covers welded and seamless wrought stainless steel pipe. Do not assume that a carbon-steel schedule table under ASME B36.10M has identical values for every stainless steel pipe size.

Verify schedule and wall-thickness values against the latest approved dimensional reference before using them for design, pressure calculations or procurement.

Stainless steel pipe dimensions include nominal size, NB or DN, OD, ID, wall thickness, schedule, length and nominal weight. The following table shows how each dimension is used.

Nominal pipe sizes are often written in inches, while actual outside diameter and wall thickness are usually shown in millimetres. Nominal size should not simply be multiplied by 25.4 to determine the actual pipe OD.

For example, 2 inches multiplied by 25.4 equals 50.8 mm, but the standardized outside diameter of NPS 2 pipe is 60.3 mm. This is why a standard pipe chart should be used instead of a simple unit conversion.

Read the nominal size, OD, schedule and wall thickness together. Do not use the nominal size alone to estimate the actual bore or flow area.

For example, a requirement for a 2-inch stainless steel pipe, Schedule 40S means:

• 2 inch: Nominal pipe size.
• 50 NB / DN 50: Nominal size designation.
• 60.3 mm: Standard outside diameter.
• 40S: Stainless steel schedule designation.
• 3.91 mm: Nominal wall thickness for the selected size and schedule.
• ID: Calculated from OD and wall thickness.

The final purchase description should also identify the stainless steel grade, pipe type, applicable product specification, length, quantity, end finish and testing or certification requirements.

Selecting a stainless steel pipe size requires more than matching an inch or NB designation. Consider the service conditions, required flow, connections, material grade and applicable engineering standard.

• Flow rate: Select an appropriate internal diameter for the required flow and allowable pressure loss.
• Operating pressure: Confirm the required wall thickness and schedule through the applicable design code.
• Operating temperature: Check the temperature limits and material properties for the application.
• Material grade: Select SS 304, SS 316L, duplex or another grade according to corrosion, temperature and service requirements.
• Pipe type: Specify seamless or welded construction where required by the design or product specification.
• Connections: Match the OD and wall details with fittings, valves, flanges and equipment.
• Standard: Confirm the applicable dimensional and material standards before ordering.
• Installation: Consider pipe weight, supports, available space, bending, fabrication and handling.

When requesting a quotation, provide the stainless steel grade, NPS or NB size, schedule or wall thickness, seamless or welded type, applicable standard, quantity and required length.

• Stainless Steel Pipe Weight Chart
• Stainless Steel Pipe Thickness Chart
• SS 304 Seamless Tubes
• SS 316L Seamless Pipes
• Request Stainless Steel Pipe Sizes and Pricing

Request Stainless Steel Pipe Sizes and Pricing

Kamal Steels supplies stainless steel pipes in different grades, sizes, schedules and specifications. Send your required grade, size, schedule, pipe type, quantity and length to confirm availability and receive technical and commercial details.

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