Schedule 40 Black Iron Pipe

These dimensions align with ASTM A53 Schedule 40 manufacturer data and the ASME B36.10 dimensional system. NPT threads-per-inch values follow ASME B1.20.1.

Schedule 80 Black Steel Pipe Quick Chart

Black iron pipe is a long-standing trade term generally referring to uncoated black steel pipe. Modern products commonly sold for these applications are produced to standards such as ASTM A53 rather than being literal wrought-iron pipe. ASTM A53/A53M-24 explicitly covers black steel pipe, hot-dip galvanized steel pipe, welded pipe, and seamless pipe.

In modern trade usage, black iron pipe generally means black or uncoated steel pipe, but black steel pipe is the technically clearer term. The dark surface comes from the mill or manufacturing finish rather than a zinc galvanizing layer. Manufacturers commonly list standard steel pipe with finish options including black and hot-dip galvanized under the same base product line. This chart uses both terms because users search both.

For the complete OD reference across every material system, see the Pipe Outside Diameter Chart.

For the complete ID reference and calculation methodology, see the Pipe Inside Diameter Chart.

These dimensions match Wheatland’s published ASTM A53 Schedule 40 submittal data and confirm compatibility with welding, threading, and grooving for common sizes.

Useful for heavier-duty mechanical and process contexts; see the Schedule 80 Pipe Chart for the complete dataset.

At the same NPS, both schedules normally share the same OD; the difference is entirely in wall thickness, ID, and weight.

Potential schedules under ASME B36.10 can include 10, 20, 30, 40, 60, 80, 100, 120, 140, and 160, depending on NPS. Not every schedule exists at every size. See the Pipe Schedule Chart for the complete schedule availability reference.

The current ASTM A53/A53M-24 specification covers seamless and welded pipe, black and hot-dipped galvanized steel pipe, from NPS 1/8 through NPS 26, with specified wall thicknesses and applicable testing requirements. Dimensional data in this chart is tied to ASME B36.10 where appropriate, since A53 defines the product and material requirements while B36.10 defines the dimensional system.

ASME B36.10-2022 applies to welded and seamless wrought steel pipe dimensional standardization, providing NPS/DN designations, outside diameter, wall thickness, and nominal weight. This standard governs dimensions; ASTM A53 governs the material and product requirements for the black or galvanized finish. These are two separate layers of the same pipe specification.

Availability of a given type depends on size, grade, and manufacturer. For example, some manufacturers use A53 Type F Grade B for certain smaller Schedule 40 products and Type E Grade B for larger products. Do not assume all black pipe uses one universal manufacturing type.

Grades affect mechanical requirements such as minimum yield and tensile strength. Grade does not change the basic NPS dimensional designation by itself; a Grade A and Grade B pipe of the same NPS and schedule share identical OD, wall thickness, and ID.

For the complete multi-material weight reference, see the Pipe Weight Chart and Steel Pipe Weight Chart.

Manufacturer and trade data commonly list 20 ft and 21 ft as standard lengths for black steel pipe, depending on the specific product and market. Do not assume every black pipe product comes only in those lengths; verify actual stock lengths with the supplier before finalizing a material order.

Use ASME B1.20.1-2013 (R2018), which covers NPT and related inch pipe-thread series and remains in effect under stabilized maintenance. For detailed thread geometry, see the NPT Thread Chart and Pipe Thread Chart.

Black steel pipe produced to ASTM A53 is commonly specified as suitable for welding, threading, or grooving depending on the product. Dimensions of the base pipe remain tied to the relevant NPS and schedule regardless of end preparation.

Fittings are selected by nominal pipe size, not measured OD labels. A 1/2-in black pipe uses a 1/2-in threaded fitting, and a 3/4-in black pipe uses a 3/4-in fitting, but the actual OD remains larger than the nominal designation in both cases.

ASTM A53 covers both black steel and hot-dipped zinc-coated steel pipe. Actual applicable service and code requirements should still be checked; do not assume every application allows either finish interchangeably. See the Galvanized Pipe Size Chart for the galvanized-specific reference.

Steel pipe is the broad category, while black iron pipe usually refers to a particular black-finish carbon steel pipe product or trade category. Not every steel pipe product should automatically be called black iron pipe; the term typically implies the specific uncoated finish and common ASTM A53 product line discussed throughout this chart.

For nominal 1/2-in, black steel pipe has an OD of 0.840 in, while standard plumbing copper tube of nominal 1/2-in size uses a different OD system entirely, with an actual OD of approximately 0.625 in. Do not assume direct dimensional interchangeability between these two nominal size systems. See the Copper Pipe Size Chart for complete copper dimensional data.

IPS-based PVC pipe often shares familiar outside diameters with NPS steel pipe. But the materials differ in joining method, temperature performance, pressure and service rules, and code applicability. Similar OD does not mean black steel and PVC are interchangeable for a given application. See the PVC Pipe Size Chart for complete PVC dimensional data.

Black steel pipe is commonly used in fuel gas piping systems. Pipe diameter selection for gas service depends on gas demand, allowable pressure drop, gas properties, developed length, fittings, and applicable code sizing tables, not on the dimensional chart alone.

Gas pipe capacity depends on inlet pressure, allowable pressure drop, gas specific gravity, developed length, fittings, demand in BTU/h or CFH, and the applicable sizing method specified by the governing fuel gas code. This chart provides dimensional data only; it does not replace a proper code-based gas pipe sizing calculation.

ASTM A53 Schedule 40 black steel pipe is available in versions that are UL Listed and FM Approved for sprinkler applications in listed sizes. Product listing and fire-system design requirements, not the dimensional chart alone, control actual sprinkler system use. This page provides dimensional reference only, not sprinkler system design guidance.

Black steel pipe is used in general applications such as steam, compressed air, mechanical piping, and industrial service, subject to material grade, pressure and temperature limits, the applicable piping code, and joining method. Generic black pipe is not automatically suitable for every pressure and temperature service; verify the correct grade, schedule, and code requirements for the specific application.

Since the OD is normally the same for both schedules at a given NPS, you need wall thickness, ID, or product marking to tell them apart. For NPS 2, Schedule 40 has a wall of 0.154 in while Schedule 80 has a wall of 0.218 in.