49 CFR § 230.24 - Maximum allowable stress.

---
identifier: "/us/cfr/t49/s230.24"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "49 CFR § 230.24 - Maximum allowable stress."
title_number: 49
title_name: "Transportation"
section_number: "230.24"
section_name: "Maximum allowable stress."
chapter_name: "FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION"
part_number: "230"
part_name: "STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "49 U.S.C. 20103, 20107, 20702; 28 U.S.C. 2461 note; and 49 CFR 1.89."
regulatory_source: "64 FR 62865, Nov. 17, 1999, unless otherwise noted."
cfr_part: "230"
---


# 230.24 Maximum allowable stress.

(a) *Maximum allowable stress value.* The maximum allowable stress value on any component of a steam locomotive boiler shall not exceed 
1/4 of the ultimate tensile strength of its material.

(b) *Safety factor.* When it is necessary to use the code of original construction in boiler calculations, the safety factor value shall not be less than 4.