Schedule Steel Pipe Dimensions Chart (SCH 10 to XXS)

Schedule 10 Pipe Dimensions

The lightest wall thickness in the carbon steel pipe schedule system is Schedule 10. SCH 10 pipes are utilised in HVAC ductwork connections, low-pressure water lines, fire sprinkler distribution, and dry sprinkler systems when weight reduction is important. They are also utilised in food processing, pharmaceutical, and architectural piping where appearance and weight are more important than pressure capacity.

The full Schedule 10 steel pipe dimensions per ASME B36.10M are listed below.

Standard: ASME B36.10M. All dimensions in mm. Weight in kg/m for carbon steel.

Schedule 20 Pipe Dimensions

ASME B36.10M defines Schedule 20 as a light-wall standard for pipes NPS 8 inches and larger. Since smaller pipes lack this thickness, engineers select it for low to medium pressure needs. You will find it in water lines, drainage headers, fire mains, and ventilation systems across industrial plants and various large-scale commercial building projects today.

The Schedule 20 steel pipe dimensions per ASME B36.10M are listed below.

Schedule 40 Steel Pipe Dimensions

Schedule 40 is the most widely used pipe schedule worldwide. It provides a balanced combination of wall thickness, pressure rating, and cost, making it the default choice for general-purpose water, gas, air, and structural applications. Schedule 40 and Standard Weight (STD) are equivalent for NPS 1/8 inch through NPS 10 inch. From NPS 12 inch upwards, the wall thicknesses diverge.

The complete Schedule 40 steel pipe dimensions per ASME B36.10M are listed below, including outside diameter, wall thickness, inside diameter, and weight per metre.

Schedule 80 Steel Pipe Dimensions

Schedule 80 pipes feature thicker walls than Schedule 40 for the same OD, boosting pressure ratings and mechanical strength. For high-pressure gas, chemical processing, and steam lines where impact or corrosion risk exists, SCH 80 works best. Notably, Schedule 80 and Extra Strong (XS) offer identical specifications for sizes up to NPS 8 inch. For NPS 10 and larger, their wall thicknesses diverge.

Schedule 80 pipes have a smaller interior diameter than Schedule 40 pipes of the same NPS because the OD is fixed and the wall is thicker. This reduces flow capacity and must be considered in hydraulic design.

Schedule 120 Pipe Dimensions

Schedule 120 is a heavy-wall specification engineered for high-pressure and high-temperature service. ASME B36.10M sets this for sizes 4 inches and up. It is the middle option for Schedule 80 and Schedule 160. Schedule 120 is the preferred choice for steam headers, boiler feed water lines and refinery piping when Schedule 80 is insufficient, but Schedule 160 is excessive.

The Schedule 120 steel pipe dimensions per ASME B36.10M are listed below.

Standard: ASME B36.10M. All dimensions in mm. Weight in kg/m for carbon steel. SCH 120 is not defined for NPS sizes below 4 inch.

Schedule 160 Pipe Dimensions

Sch 160 is a very heavy-wall pipe used for high-pressure and high-temperature service, including hydraulic systems and steam lines. It is defined for NPS 1/2"12" in ASME B36.10M. Schedule 160 is not the same as XXS, although they are close in wall thickness at some sizes. Compare these values in the table below.

Standard: ASME B36.10M. All dimensions in mm. Weight in kg/m for carbon steel.

XXS (Double Extra Strong) Steel Pipe Dimensions

XXS (Double Extra Strong, also called XXH or DEXS) is the heaviest wall-thickness in the traditional STD, XS, and XXS system. It is used for high-pressure applications such as sour gas transport, subsea pipelines, hydraulic systems, and critical process lines. XXS is defined only for smaller sizes and is generally not available above NPS 8". Refer to the table below for dimensions

Schedule 40 vs Schedule 80 Steel Pipe Comparison

Schedule 40 and Schedule 80 for the same NPS differ in significant dimensions, as shown in the table below. ODs are identical for both schedules. Only wall thickness, internal diameter, and weight vary. Utilise this table to rapidly identify if your application needs SCH 40 to SCH 80 upgrade.

Key rule: If Schedule 40 meets design pressure, utilise it. Lower cost, higher flow capacity. Only use Schedule 80 for pressure rating, corrosion allowance, or mechanical load.

Steel Pipe Schedule Pressure Ratings (Carbon Steel ASTM A106 Grade B)

Per ASME B31.3, the pressure ratings below are approximate maximum permissible working pressures (MAWP) for carbon steel ASTM A106 Grade B pipe at 38C. Pressure rating decreases with pipe size and operating temperature. Always check your service conditions with your piping engineer and the code.

Important: These are ambient temperature reference values. Carbon steel's allowed stress and pressure rating decreases above 100C. Refer to the material standard and consult your engineering team for stainless steel, duplex, and alloy pipe schedules.

NPS to DN Conversion Chart (Nominal Pipe Size to Nominal Diameter)

NPS (Nominal Pipe Size) is the North American designation used in ASME standards. DN (Diametre Nominal) is the equivalent metric designation used in ISO, DIN, and EN standards. For NPS 4 and above, DN equals NPS multiplied by 25 exactly. Below NPS 4, the relationship is not a round multiplication. Use the table below as the definitive reference.

How to Read a Steel Pipe Schedule Chart

A pipe schedule chart contains six pieces of information for every pipe size. Reading the chart correctly takes only four steps, given below. This section explains each column, walks through one complete row as a worked example, and shows the formulas you can use to verify any value yourself.

1. Step 1: Find your pipe size in the NPS or DN column
   Every schedule chart has NPS (Nominal Pipe Size) in inches in the first column. The second column is DN (Diameter Nominal) in millimetres. We utilise NPS for American and project specs. We also use DN for European and Indian projects. A 4-inch pipe is equivalent to DN 100. Find your size in either column and read across the row.
2. Step 2: Read the OD value (the actual outside diameter)
   The third column displays the outside diameter in mm. This represents the true external diameter of the pipe and is the most significant value in the chart. OD remains unaffected by the schedule. Both SCH 40 and SCH 80 four-inch pipes possess an outside diameter of 114.3 mm. Always dimension fittings, flanges, and supports according to outer diameter (OD), not nominal pipe size (NPS).
3. Step 3: Read the wall thickness for your chosen schedule
   The wall thickness column indicates the pipe wall thickness in mm. This value is different for the schedule. The higher the schedule number, the thicker the wall. Pipe wall thickness impacts weight and pressure capability. Follow the schedule in your project drawing or BOQ.
4. Step 4: Calculate or read the inside diameter (ID)
   The ID represents the bore where fluid flows. It is computed as OD minus twice the wall thickness. For a 4-inch SCH 40 pipe, ID = 114.3 - (2 6.02) = 102.26 mm. The chart already shows this value, but knowing the formula allows you to validate any row.
5. Worked Example: Reading a 4 inch Schedule 40 row
   In order to ensure that you have a complete comprehension of the significance of each value, the following table explains on each column of the NPS 4-inch Schedule 40.

Steel Pipe Schedule Applications Guide

The schedule you select determines the pressure capacity, weight, and cost of your piping system. The table below lists the typical applications and industries for each major schedule.

Pro tip: SCH 40 carbon steel (ASTM A106 Grade B or IS 1239 medium class equivalent) is used in 80% of Indian industrial and construction applications. Only use SCH 80 or heavier where the line pressure calculation, corrosion allowance, or project specification requires it.

Why Source Schedule Steel Pipe from Sachiya Steel International

Sachiya Steel International Pvt. Ltd. stocks and supplies Schedule 10, 20, 40, 80, 120, 160, and XXS carbon and stainless steel pipes in Mumbai. We stock seamless (ASTM A106 Grade B, ASTM A53) and ERW. Mill test certificates are on every ex-stock merchandise in our warehouse for prompt shipment.

• SCH 10 to XXS ex-stock: NPS 1/2 inch to NPS 24 inch available from our Mumbai warehouse without minimum lead time.
• ASTM A106 Gr. B and ASTM A53: carbon steel seamless and ERW, certified to ASME B36.10M.
• ASTM A312 stainless: SS 304, SS 316L, and duplex grades in standard schedules per ASME B36.19M.
• Mill Test Certificates (MTC): provided signed and stamped per EN 10204 3.1 with every shipment.
• Traceability: heat number and cast number traceable back to original mill for all orders.
• Value-added processing: cut-to-length, end beveling, threading, hydrostatic testing, and coating available in-house.
• PAN-India dispatch: export-ready documentation for GCC, Africa, and Southeast Asia buyers.
• Quote turnaround: written quote with price, lead time, and stock status within working hours via WhatsApp or email.