Stress-Corrosion Cracking

Stress-corrosion cracking (hyphenated variant) is an alternate written form of stress corrosion cracking (SCC), referring to the same failure mechanism in which tensile stress, a susceptible material, and a specific corrosive environment act together to propagate cracks subcritically through a metal at stress intensity levels well below the fracture toughness of the material in the absence of the corrosive environment.

Key Takeaways

The hyphenated form "stress-corrosion cracking" and the unhyphenated form "stress corrosion cracking" refer to the same phenomenon; both are used in technical literature, standards documents, and regulatory filings, with the choice reflecting author preference or house style rather than any technical distinction.
NACE MR0175 / ISO 15156, the governing standard for sour service material selection, uses the unhyphenated form "stress corrosion cracking" and the abbreviation SCC, which is the more common convention in current industry standards.
The three prerequisite conditions for stress-corrosion cracking are always the same regardless of hyphenation: a susceptible material, a specific corrosive environment matched to that material's susceptibility, and sufficient sustained tensile stress.
In the oil and gas context, the most commonly encountered forms are sulfide stress cracking (SSC) in H2S environments affecting high-strength steels, chloride stress-corrosion cracking in stainless steels, and carbonate-bicarbonate stress-corrosion cracking in external pipeline environments.
Prevention strategies are material-based (selecting resistant alloys), environmental (inhibitor injection, coating, deaeration), stress-based (heat treatment to reduce residual stress, design to minimize stress concentration), or operational (reducing operating pressure below critical thresholds for susceptible materials).

Fast Facts

The hyphenated form "stress-corrosion cracking" appears in older literature (pre-1980s) more frequently than in modern standards, which have largely standardized on the unhyphenated abbreviation SCC. ASTM G129 (Practice for Slow Strain Rate Testing to Evaluate the Susceptibility of Metallic Materials to Environmentally Assisted Cracking) uses both forms, reflecting the historical variability. The key practical implication of the hyphenation issue is recognizing that when regulatory documents, engineering reports, or failure analyses refer to stress-corrosion cracking, stress corrosion cracking, or SCC, they are all describing the same failure mechanism and the same body of standards and literature applies.

What Is Stress-Corrosion Cracking?

Stress-corrosion cracking is the same mechanism as stress corrosion cracking (SCC) — the hyphen is a grammatical variant, not a technical distinction. Both terms describe the phenomenon in which a metal component fails by cracking under conditions of simultaneous tensile stress and exposure to a specific corrosive environment, producing brittle fracture at stresses well below the material's normal fracture resistance.

For the complete technical description of the mechanism, material-environment systems, testing standards, and mitigation strategies, see the primary entry at stress corrosion cracking and the abbreviation entry at SCC.

The practical importance of recognizing this nomenclature equivalence is that all relevant standards (NACE MR0175 / ISO 15156, NACE SP0204, API RP 1176, ASTM G49, ASTM G129) and regulatory requirements apply equally whether the failure mechanism is called stress-corrosion cracking or stress corrosion cracking in the document being reviewed. Engineers searching for failure analysis literature, regulatory requirements, or testing methods should include both forms in database searches to avoid missing relevant references.

Stress-Corrosion Cracking in Oil and Gas Practice

Canada (CER / AER): Canadian regulatory documents including CER pipeline integrity management requirements and AER well completion directives use both hyphenated and unhyphenated forms depending on the era of the document and the drafting convention used. The AER's sour service requirements in Directive 008 reference NACE MR0175 / ISO 15156, which uses "stress corrosion cracking" (unhyphenated). Engineers reviewing older Alberta regulatory records may encounter the hyphenated form; the requirements and standards referenced are the same.

United States (PHMSA / NACE): PHMSA regulations use "stress corrosion cracking" (unhyphenated) consistently in 49 CFR 192 and 195 and in related advisory bulletins. NACE International's standards database, now maintained by AMPP, uses SCC as the abbreviation and unhyphenated full form in current documents. Older NACE publications and some API recommended practices may use the hyphenated form.

Norway (Sodir / NORSOK): NORSOK standards use the unhyphenated English form "stress corrosion cracking" consistent with ISO and NACE conventions. Norwegian-language petroleum publications use the equivalent Norwegian term, but engineering documentation for international operations is standardized in English following ISO terminology.

Middle East (Saudi Aramco): Saudi Aramco Engineering Standards reference NACE MR0175 / ISO 15156 and use "stress corrosion cracking" (unhyphenated) in technical documents. The abbreviation SCC appears in Aramco's failure analysis and materials selection documentation consistent with international convention.

Stress-corrosion cracking is the same as stress corrosion cracking and is abbreviated SCC. Closely related mechanisms under the umbrella of "environmentally assisted cracking" include sulfide stress cracking (SSC), hydrogen embrittlement, hydrogen-induced cracking (HIC), and corrosion fatigue. The terms "environmentally assisted cracking" (EAC) and "environment-assisted cracking" are broader umbrella terms that include all of these mechanisms.

Tip: When writing engineering documents, failure reports, or regulatory submissions that will be shared internationally, standardize on the unhyphenated "stress corrosion cracking" and the abbreviation SCC, consistent with current ISO, NACE (AMPP), and API usage. This avoids confusion and ensures the document aligns with the terminology used in the standards it references. The hyphenated form is grammatically defensible but creates unnecessary search and cross-reference issues in an industry where database keyword matching is used to track failure modes across large asset populations.

FAQ

Is there any technical difference between stress-corrosion cracking and stress corrosion cracking?
No. The hyphen in "stress-corrosion cracking" reflects a grammatical choice — "stress-corrosion" as a compound modifier before "cracking" — but carries no technical distinction from "stress corrosion cracking." Both forms appear in the scientific and engineering literature and both refer to the same mechanism. NACE MR0175 / ISO 15156, the most authoritative standard for this failure mode in oil and gas service, uses the unhyphenated form and the abbreviation SCC.

What is the relationship between SCC and environmentally assisted cracking?
Environmentally assisted cracking (EAC) is the umbrella term covering all cracking mechanisms in which a chemical environment facilitates crack initiation or propagation in metals under stress. SCC (stress corrosion cracking) is the most broadly used form of EAC and encompasses all cases where the combined action of stress and specific environment enables subcritical crack growth. Hydrogen embrittlement, sulfide stress cracking (SSC), corrosion fatigue, and liquid metal embrittlement are all specific forms of EAC that share some features with classical SCC but involve distinct mechanisms that are distinguished in ASTM, NACE, and ISO test standards.

Why This Entry Matters

Nomenclature consistency in technical and regulatory documentation reduces the risk of search-and-retrieval failures that can lead engineers or regulators to miss critical failure mode information. Identifying stress-corrosion cracking (hyphenated) and stress corrosion cracking (unhyphenated) as the same phenomenon ensures that professionals reviewing historical records, failure databases, and regulatory archives retrieve the complete body of relevant information regardless of the era or drafting convention of the source document.