Pipe Wall Thickness Chart: SCH 5S to SCH XXS (ASME B36.10 / B36.19)

Pipe Wall Thickness Overview

Pipe wall thickness is the dimension between the outer and inner surfaces of the pipe, measured in millimeters (or inches for US customary). It is the single most important dimensional parameter determining pressure capacity, weight, and cost. Wall thickness is specified by the Schedule (SCH) designation, which provides a standardized system for selecting the appropriate thickness for a given nominal size and service condition. The measurement of wall thickness can be performed using calipers (direct measurement of accessible pipe ends) or ultrasonic thickness gauges (non-destructive measurement of installed pipe).

Two standards govern pipe wall thickness: ASME B36.10 for carbon and alloy steel, and ASME B36.19 for stainless steel. The two standards use different wall thickness values for the same nominal Schedule designation. The most obvious difference is the "S" suffix in stainless steel schedules (SCH 5S, 10S, 40S, 80S), which indicates these are from the B36.19 standard. For SCH 40S and 80S, wall thicknesses are generally identical to the carbon steel equivalents for sizes 12" and below, but SCH 5S and 10S have thinner walls unique to stainless steel.

Carbon Steel Wall Thickness Chart (ASME B36.10)

1/2" - 4" Carbon Steel Pipe Schedule Wall Thickness

6" - 12" Carbon Steel Pipe Schedule Wall Thickness

14" - 24" Carbon Steel Pipe Wall Thickness

For pipe sizes 14" and above, the wall thicknesses for SCH 20, 30, 40, 60, and 80 are specified. Notably, 14" and above uses Standard (STD) weight walls rather than the SCH 40 designation for the thinner schedule. STD for 14" pipe is 9.53 mm, which is equivalent to SCH 20 for some sizes. The maximum wall thickness available as standard for these sizes is typically SCH 80 (12.70 mm for most diameters) or XS (Extra Strong).

Stainless Steel Wall Thickness Chart (ASME B36.19)

1/2" - 4" Stainless Steel Pipe Schedule Wall Thickness

6" - 12" Stainless Steel Pipe Schedule Wall Thickness

Wall Thickness for Stainless Steel Schedule Series

SCH 5S is the thinnest wall series in the stainless steel schedule system. With wall thicknesses as low as 1.65 mm for small bores, SCH 5S is designed for low-pressure sanitary and beverage applications where pressure containment is not the primary requirement. The thin walls reduce weight and cost while providing adequate flow capacity for gravity-fed and low-pressure systems.

SCH 10S is slightly thicker than SCH 5S and is commonly used in food and pharmaceutical processing, dairy production, and light chemical applications where moderate pressures (up to 10-15 bar) are encountered. The additional wall thickness provides improved structural integrity while maintaining light weight and good weldability.

SCH 40S is the standard wall thickness for stainless steel pipe, with wall thickness values generally identical to carbon steel SCH 40 for sizes 12" and below. This allows the same fittings to be used for both carbon and stainless steel pipe of the same schedule, simplifying procurement and inventory management.

SCH 80S provides extra-strong walls for high-pressure stainless steel piping systems. Like SCH 40S, the wall thicknesses are identical to carbon steel SCH 80 for sizes 12" and below, ensuring fitting compatibility across materials.

Thin Wall vs Thick Wall: Performance & Cost Analysis

Thin-wall pipes (SCH 5S, 10S) offer advantages in material cost, weight, and ease of welding, but are limited to low-pressure applications and have reduced corrosion allowance. Standard-wall pipes (SCH 40, STD) provide the best balance of strength, weight, and economy for general industrial applications. Thick-wall pipes (SCH 80, 160, XXS) support higher pressures and provide additional corrosion allowance but at significantly higher material cost - typically 40-100% more than SCH 40 for the same nominal size. The economic analysis must consider not only the material cost but also the increased welding time, heavier supports, and higher transportation costs associated with thicker walls.

Wall Thickness Tolerance

Per ASTM A530/A999, the wall thickness tolerance for seamless pipe is typically +20% / -12.5% for sizes up to 4" and +22.5% / -12.5% for larger sizes. For welded pipe, tolerances are generally +15% / -10%. These tolerances mean that the minimum wall thickness at the thinnest point could be 12.5% less than the nominal schedule thickness. Engineers must account for this negative tolerance when calculating minimum wall thickness for pressure design. Many specifications require ordering to a minimum wall (min wall) specification, which ensures that no point on the pipe falls below the specified minimum thickness.

Wall Thickness & Weight

Pipe weight increases linearly with wall thickness. A 4-inch SCH 80 pipe weighs approximately 39% more than SCH 40 per meter (22.32 vs 16.08 kg/m). This additional weight impacts not only material cost but also the cost of supports, foundations, and transportation. For large-diameter, thick-wall pipe, the weight difference can translate into tens of thousands of dollars in additional structural steelwork and civil works costs.

Wall Thickness & Pressure Rating

Per Barlow's formula (P = 2St/D), the pressure rating is directly proportional to wall thickness. A pipe with twice the wall thickness has approximately twice the pressure rating (assuming constant OD and allowable stress). This relationship is the primary driver of schedule selection: higher-pressure systems require thicker walls. For detailed pressure rating calculations, see our Pipe Pressure Rating Guide.

How to Measure Pipe Wall Thickness

Ultrasonic thickness (UT) gauges are the standard tool for non-destructive wall thickness measurement. The gauge sends high-frequency sound waves through the pipe wall and measures the time for the echo to return. This method can measure wall thickness from one side of the pipe, making it ideal for in-service inspection. Calipers can measure wall thickness at pipe ends during fabrication. Key considerations include surface preparation (remove loose scale and coatings), couplant selection (gel for rough surfaces), and calibration on a known-thickness standard.

Our Supply Capability

ManufacturerPipe supplies all schedule wall thicknesses from SCH 5S through XXS. We maintain inventory of the most common schedules (SCH 40, 80, 160) in carbon, alloy, and stainless steel. For special requirements, we offer non-standard wall thickness customization for projects where standard schedule increments are either insufficient or provide excessive conservatism.

Need Pipe Wall Thickness Guidance?

Contact our engineering team for wall thickness selection assistance and competitive pricing on all schedules.

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• Stainless Steel Pipe
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