Pipe by Schedule — Companion Article

What this tool does

The page shows the outside diameter, wall thickness, inside diameter, weight, inside area, and metal area of a pipe for one NPS and one schedule or wall. It reads two interim tables: ASME B36.10 welded and seamless wrought steel pipe, and the ASME B36.19 stainless S schedules 5S, 10S, 40S, and 80S.

It has two lookups. Pipe by schedule reads the row for a schedule, an identification, or a plain wall. Pipe by wall thickness finds the row for a wall you type, or the nearest rows either side of it.

The lookup runs in the browser. Opening /tools-training/pipe-by-schedule/ with no query shows NPS 6, Schedule 40 (STD), in imperial units.

When to use it

Use it when the NPS and schedule are on the line list and you need the dimensions: the bore for a flow check, the weight for a support load, or the wall for a thickness check. Use the wall lookup when a drawing or a vendor gives a wall and you want to know which schedule it is.

Use it to tell a carbon steel schedule from a stainless S schedule. Schedule 40 and Schedule 40S are separate rows. At many sizes they share a wall. At NPS 12 and above they do not.

Use the NPS / DN / OD cross-reference when you only need the size match between NPS and DN. Use the wall thickness calculator when you need a required wall from pressure.

Inputs

1. Lookup tab: Pipe by schedule, or Pipe by wall thickness.
2. Size. The list reads NPS with its DN, for example NPS 2 (DN 50). It runs from NPS 1/8 to NPS 80, 44 sizes. The page opens on NPS 6.
3. Schedule, on the schedule tab. The list holds every row stored for the size, thinnest first within each table. A row with a schedule number reads Schedule 40 (STD). A row with an identification and no number reads XXS, wall 0.436 in. A row with neither reads Plain wall 0.083 in. Choosing a new size selects Schedule 40 where it exists.
4. Wall thickness and its unit, in or mm, on the wall tab.
5. Display units: Imperial (in, lb/ft) or SI (mm, kg/m). The other unit stays on the same line.

A query opens a row directly, for example /tools-training/pipe-by-schedule/?nps=2&schedule=40S. For the wall lookup use ?nps=2&mode=wall&wall=0.200&unit=in. Add display=si for SI. Give a schedule with the NPS on the schedule lookup.

How it works

On the schedule tab the page reads the stored row for the NPS and the schedule you chose. The outside diameter, wall, and weight are the table cells.

On the wall tab the page compares your wall with every row stored for the NPS. A wall within 0.0005 in, or 0.005 mm when you type millimetres, is an exact match. At NPS 2 a wall of 3.91 mm returns both Schedule 40 and Schedule 40S, because both rows carry that wall. Otherwise the page returns the nearest stored wall below and the nearest above, the closer one first. Below the thinnest or above the thickest wall there is only one neighbour.

The inside diameter is the outside diameter minus twice the wall. The inside area and the metal area are worked from those diameters. These three figures are labelled derived. The weight is the table weight, not a figure the page works out.

Inch and millimetre cells are both stored. They are not converted from each other on the page.

Understanding the result

Each result is a card. The heading names the NPS, the DN, the schedule, and the identification, for example NPS 6, DN 150, schedule 40, STD. A nearest row adds (nearest) to the heading.

The card lists Match (Exact or Nearest), Outside diameter, Wall thickness, Inside diameter (derived), Weight, Inside area (derived), Metal area (derived), and Key. The key is the row id, for example NPS-2-SCH-40S.

The line under the result is the provenance note for the table the row came from. A B36.19 row shows the B36.19 note. A B36.10 row shows the B36.10 note.

Some rows carry a warning. Three rows hold a corrected printed value and ask you to check against the ASME errata: NPS 2 Schedule 160, NPS 8 with a 1.125 in wall, and NPS 42 with a 0.875 in wall. NPS 18 Schedule 40S and 80S show the kg/m weight as not printed, because the source table does not print it.

Engineering considerations

STD and Schedule 40 are the same wall only up to NPS 10. At NPS 12 STD is 0.375 in and Schedule 40 is 0.406 in. Check which one the line class names.

An S schedule is a stainless table, not a carbon steel schedule with a letter added. Use 5S, 10S, 40S, and 80S for ASME B36.19 stainless pipe. The millimetre outside diameter in the two tables can be rounded differently. NPS 2 is 60.32 mm in the B36.10 row and 60.3 mm in the B36.19 row, from the same 2.375 in.

A plain wall row has no schedule number. It is a wall the table lists for that size. NPS 76 and NPS 80 are plain wall only, so the schedule list at those sizes holds walls, not schedules.

The derived inside diameter is the nominal bore. It does not take off mill tolerance, corrosion allowance, or lining.

Example

NPS 2, Schedule 40S, imperial display. Key NPS-2-SCH-40S:

• Outside diameter 2.375 in (60.3 mm).
• Wall thickness 0.154 in (3.91 mm).
• Inside diameter 2.067 in (52.48 mm), derived.
• Weight 3.66 lb/ft (5.44 kg/m).
• Inside area 3.356 in² (2163.1 mm²), derived.
• Metal area 1.075 in² (692.7 mm²), derived.

The same size at Schedule 40 (STD) is the B36.10 row. It has the same 0.154 in wall. Its outside diameter reads 2.375 in (60.32 mm) and its inside diameter 2.067 in (52.50 mm).

NPS 6, Schedule 40 (STD), the row a direct visit shows. Outside diameter 6.625 in (168.28 mm), wall 0.280 in (7.11 mm), inside diameter 6.065 in (154.06 mm), weight 18.99 lb/ft (28.26 kg/m).

NPS 4, Schedule 80 (XS). Outside diameter 4.500 in (114.30 mm), wall 0.337 in (8.56 mm), inside diameter 3.826 in (97.18 mm), weight 15.00 lb/ft (22.32 kg/m).

Wall lookup, NPS 2, 0.200 in. No row is within 0.0005 in. The page returns the plain wall 0.188 in first, as the closer wall, then Schedule 80 (XS) at 0.218 in. Both cards are marked Nearest.

Standards/references (licensed vs interim)

Both tables are interim data from public sources, pending the licensed standard.

The note on a B36.10 row reads: Interim data from ASME B36.10-2022 Table 2-1 numeric extract, not licensed ASME text. Verify against the current edition of ASME B36.10 before use.

The note on a B36.19 row reads: Interim data from the public ASME B36.19M-2018 Table 2-1, not licensed ASME text. Verify against the current edition of ASME B36.19 before use.

A citation of a standard number is not a copy of the standard. This article does not reproduce the tables. These interim figures will be replaced by licensed ASME data when it is available.

Limitations/disclaimer

The page is a table lookup. It does not calculate a required wall, check a pressure, or replace ASME B36.10 or ASME B36.19.

• The S schedules stored are 5S, 10S, 40S, and 80S, from NPS 1/8 to NPS 30 where the 2018 table prints a wall. NPS 30 has 10S only. Other S schedules are not stored.
• NPS 76 and NPS 80 are plain wall only. A schedule number at those sizes is refused.
• Three rows carry a corrected printed value. Check them against the ASME errata.
• NPS 18 Schedule 40S and 80S have no printed kg/m weight.
• Inside diameter, inside area, and metal area are derived from the outside diameter and the wall. They do not allow for mill tolerance or corrosion.
• The page does not list material grades, pressure ratings, or end preparations.

Use the tool

Calculate now: Pipe by schedule

Related tools

• NPS / DN / OD cross-reference for the size match between NPS and DN on outside diameter. Read the NPS / DN / OD companion article.
• Wall thickness for a required wall from pressure. Read the wall thickness companion article.
• Pipe volume and weight for contents and filled weight. Read the pipe volume and weight companion article.
• Pipe properties for section properties. Read the pipe properties companion article.
• Flange datasheet for the weld-neck flange that meets the pipe. Read the flange datasheet companion article.