Category
Materials, Welding & Coatings
Subcategory
Materials
Applicable standards
3
Issuing bodies
3
Description
Material requirements for wet H₂S refinery service (downstream).
Applicable Standards (3)
API — 1 standard
API 571
Damage Mechanisms Affecting Fixed Equipment in the Refining Industry
Catalog of ~70 damage mechanisms (corrosion, cracking, metallurgical, mechanical, environmental).
Key requirements (5)
- Catalog of >70 damage mechanisms in refining and petrochemical service.
- For each mechanism: description, materials affected, factors, appearance, prevention/mitigation.
- Examples: high-temp H2S corrosion, naphthenic acid corrosion, polythionic acid SCC, CUI, MIC.
- Hydrogen damage: HTHA per Nelson curves (now revised post-Tesoro 2010 incident).
- Used as input to RBI (API 580/581) and inspection planning.
ISO — 1 standard
ISO 15156 (series) / NACE MR0175
Petroleum and natural gas industries — Materials for use in H2S-containing environments in oil and gas production
Sour service material requirements for upstream — SSC, HIC, SOHIC, SZC resistance.
Key requirements (8)
- Materials for sour service (H2S) in oil & gas production — also as NACE MR0175.
- Sour service threshold: H2S partial pressure ≥ 0.05 psia (0.34 kPa).
- Carbon steel hardness limit: 22 HRC (250 HV) max — prevents SSC.
- PWHT mandatory for CS in sour service; hardness verified.
- Materials qualification: laboratory test per NACE TM0177 (Method A, B, C, D) at relevant H2S/Cl/pH.
- Region 1: SSC (sulfide stress cracking), Region 2: SOHIC, Region 3: HIC.
- 13 % Cr martensitic (S13Cr): qualified for sour service with H2S limits.
- Duplex stainless (UNS S31803/S32750): qualified by environmental severity.
NACE/AMPP — 1 standard
NACE MR0103 / ISO 17945
Petroleum, petrochemical, and natural gas industries — Metallic materials resistant to sulfide stress cracking in corrosive petroleum refining environments
Refining sour service — material requirements for SSC resistance in process units.
Key requirements (7)
- Materials for sour refinery process service (downstream complement of ISO 15156).
- Wet H2S service definition: water + H2S (any concentration in liquid water).
- Carbon steel hardness limit: 200 HB (HV 215) max in HAZ and weld.
- PWHT required for all welds in sour service.
- Charpy impact: 27 J avg / 21 J single at MDMT.
- Materials chemistry: Pcm ≤ 0.25, CE ≤ 0.43 typical for HIC resistance.
- HIC-resistant plate testing per NACE TM0284 (CLR ≤ 15%, CTR ≤ 5%, CSR ≤ 2%).