40 CFR § 420.81 - Specialized definitions.

---
identifier: "/us/cfr/t40/s420.81"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 420.81 - Specialized definitions."
title_number: 40
title_name: "Protection of Environment"
section_number: "420.81"
section_name: "Specialized definitions."
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "N"
subchapter_name: "EFFLUENT GUIDELINES AND STANDARDS"
part_number: "420"
part_name: "IRON AND STEEL MANUFACTURING POINT SOURCE CATEGORY"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "33 U.S.C. 1311, 1314, 1316, 1317, 1318, 1342, and 1361."
regulatory_source: "47 FR 23284, May 27, 1982, unless otherwise noted."
cfr_part: "420"
---


# 420.81 Specialized definitions.

(a) The term *salt bath descaling, oxidizing* means the removal of scale from semi-finished steel products by the action of molten salt baths other than those containing sodium hydride.

(b) The term *salt bath descaling, reducing* means the removal of scale from semi-finished steel products by the action of molten salt baths containing sodium hydride.

(c) The term *batch, sheet and plate* means those descaling operations that remove surface scale from sheet and plate products in batch processes.

(d) The term *batch, rod and wire* means those descaling operations that remove surface scale from rod and wire products in batch processes.

(e) The term *batch, pipe and tube* means those descaling operations that remove surface scale from pipe and tube products in batch processes.

(f) The term *continuous* means those descaling operations that remove surface scale from the sheet or wire products in continuous processes.

(g) The term *batch* means those descaling operations in which the products are processed in discrete batches.