NAICS 331511

Overview

The North American Industry Classification System (NAICS) is the federal standard for categorizing business establishments to support the collection, analysis, and publication of statistics on the U.S. economy. Developed under the Office of Management and Budget with the Economic Classification Policy Committee, Statistics Canada, and Mexico’s INEGI, NAICS replaced the SIC in 1997 and is currently maintained on the 2022 vintage basis. ¹
U.S. industry code 331511 covers establishments primarily engaged in pouring molten pig iron or iron alloys into molds to make iron castings (for example, cast iron manhole covers, cast iron pipe, and cast iron skillets). Establishments in this industry purchase iron produced elsewhere; when casting is followed by further manufacturing of finished products, classification shifts to the industry of the finished good. ²

What this NAICS covers

• Pouring molten pig iron or iron alloys into molds or dies to produce castings. ²
• Manufacturing cast iron components such as manhole covers and similar municipal castings. ²
• Casting iron pipe and other iron cast products identified in official examples (e.g., cookware like skillets). ²
• Casting iron pipe fittings and couplings without machining. ²
• Performing routine casting finishing steps typical for foundries (e.g., cleaning and deburring). ³
• Producing iron castings while purchasing iron from other establishments, not smelting primary iron on site. ²

Related NAICS and PSC codes

Type	Code	Descriptor
NAICS	331512	Steel Investment Foundries
NAICS	331513	Steel Foundries (except Investment)
NAICS	331523	Nonferrous Metal Die-Casting Foundries
NAICS	331524	Aluminum Foundries (except Die-Casting)

Classification notes and boundaries

• Foundries that cast iron and then further manufacture into finished products are classified by the finished product’s industry, not in 331511. ²
• Casting iron pipe fittings and couplings without machining is in 331511; fittings made from purchased pipe or plastics are classified elsewhere. ²
• Nonferrous metal casting is outside 331511 and falls under the nonferrous foundries group (e.g., 331523, 331524). ²
• Forging and stamping do not use molten metal and are excluded from primary metal manufacturing; these are classified in subsector 332 Fabricated Metal Product Manufacturing. ²

Frequently asked questions

• What activities define NAICS 331511?
  Establishments pour molten pig iron or iron alloys into molds to produce castings. Illustrative products include cast iron manhole covers, cast iron pipe, and cast iron cookware. The iron used is purchased from other producers rather than smelted on site. ²

• Are machining or finishing operations part of this industry?
  Foundries may perform standard finishing like cleaning and deburring on their castings. More extensive operations such as precision machining to tight tolerances are classified in the industry of the finished product rather than in the foundry industries. ³

• How does 331511 differ from 331513?
  331511 covers iron castings, while 331513 covers steel castings (except investment). Each code is defined by the metal cast and the process (investment vs. other), with establishments purchasing metal from other producers. ²

• Where are cast iron pipe and fittings classified?
  Manufacturing cast iron pipe and fittings, and casting iron couplings and pipe fittings without machining, is classified in 331511. Products made from purchased metal pipe or plastics are classified in different NAICS codes. ²

• What is the current NAICS vintage used in federal manufacturing data?
  The 2022 Economic Census and related manufacturing statistics are published on a 2022 NAICS basis, which is the current classification vintage for sector 31–33 (Manufacturing). ⁴

Useful resources

• G2X — NAICS 331511
• U.S. Census Bureau — NAICS Search and 2022 NAICS overview. ¹
• U.S. Census Bureau — NAICS 3315/331511 detailed industry descriptions and cross-references. ²
• U.S. Census Bureau — 2022 Economic Census: Manufacturing (NAICS 31–33) data resources. ⁴
• U.S. Census Bureau — Employer Categories showing Foundries (includes 331511). ⁵

References

1. U.S. Census Bureau, NAICS Search and Introduction to NAICS (2022 vintage). https://www.census.gov/naics/?details=33111&input=33111&year=2022
2. U.S. Census Bureau, NAICS Sector 31–33 archives page with 3315/331511 definitions and cross-references. https://www.census.gov/naics/resources/archives/sect31-33.html
3. U.S. Census Bureau, NAICS Sector 31–33 archives page — Foundries group notes (cleaning/deburring; manufacturing boundaries). https://www.census.gov/naics/resources/archives/sect31-33.html
4. U.S. Census Bureau, 2022 Economic Census — Manufacturing (NAICS 31–33). https://www.census.gov/data/tables/2022/econ/economic-census/naics-sector-31-33.html
5. U.S. Census Bureau, Employer Categories and Corresponding Establishment NAICS Industries — Foundries. https://www.census.gov/programs-surveys/esp/guidance/employer.html