NACE MR0175 / ISO 15156 — 22 HRC Max Hardness

NACE MR0175 Sour Service Valves — API 600, API 6D, H₂S Certified, Saudi Arabia

Gulf Union Ozone stocks NACE MR0175 compliant gate, ball, check, and globe valves for Saudi Aramco wet H₂S sour service applications. All valves carry production hardness certification to 22 HRC maximum, SAEP-347 Annex 3 material numbers, and EN 10204 3.1 MTCs. Available from Jeddah stock — same-day dispatch on standard sizes. Trusted by EPC contractors on Saudi Aramco, SABIC, and NGL processing facilities across the Kingdom.

Submit RFQ
NACE MR0175 sour service valves — API 600 gate valves and API 6D ball valves for H₂S service in Saudi Arabia — Gulf Union Ozone Jeddah
Sour Service Definition

What is H₂S Sour Service? — NACE MR0175 / ISO 15156

Sour service is defined by NACE MR0175 / ISO 15156 as exposure to a fluid containing water AND hydrogen sulfide (H₂S) above a defined partial pressure threshold. Wet H₂S environments cause two specific failure modes in steel valve components: Sulfide Stress Cracking (SSC) — rapid brittle cracking under tensile stress in high-hardness steel, and Hydrogen Induced Cracking (HIC) — internal cracking caused by hydrogen atoms diffusing into the steel lattice. Both failure modes are prevented by limiting material hardness and controlling chemical composition.

NACE MR0175 Sour Service Threshold
  • H₂S partial pressure ≥ 0.0003 MPa (0.05 psia) in gas phase
  • Or total pressure ≥ 0.4 MPa (65 psia) AND H₂S ≥ 0.05 mol%
  • Water must be present (wet H₂S) — dry H₂S does not trigger SSC
  • Applies to all metal components in contact with the fluid
  • Saudi Aramco uses SAEP-347 to implement MR0175 for all procurement
Key NACE MR0175 Valve Requirements
  • Max hardness: 22 HRC (250 HBW / 237 HV10) — all load-bearing components
  • Body/bonnet: WCB, WCC, WC6, WC9 with normalized heat treatment
  • Stem: 410SS or Alloy 20 (not 316SS — susceptible to SSC)
  • Bolting: ASTM A193 B7M / A194 2HM (M = MR0175 compliant)
  • Trim: 13Cr (410SS) standard; HF-overlay for erosive sour service
  • No cold work: Any cold-worked surfaces above 22 HRC → rejected
Hardness Certification — What GUO Provides
  • EN 10204 3.1 MTC with per-piece hardness readings
  • Body, bonnet, stem, and bolting all tested
  • Brinell and Rockwell readings documented
  • Mill NACE compliance statement
  • SAEP-347 Annex 3 material number reference
In Summary

Sour service is defined by NACE MR0175 / ISO 15156 as any H₂S-containing environment where the partial pressure of H₂S exceeds 0.3 kPa (0.05 psia) in the gas phase, or when the total absolute pressure exceeds 1.8 MPa (265 psia) with any detectable H₂S. In these conditions, standard valve body materials can suffer hydrogen-induced cracking (HIC) and sulfide stress cracking (SSC), making NACE MR0175 compliance mandatory for Saudi Aramco sour service piping.

Valve Product Range

Sour Service Valve Types — NACE MR0175 Compliant Stock

Valve Type Standard Body Material Trim Sizes (Stock) SAEP-347 No. Stock
Gate Valve API 600 WCB (A216), WC6 (A217) 13Cr (NACE trim) DN 25–DN 600 V-025, V-026 Ex-stock
Ball Valve (FTF) API 6D WCB, LCC (A352) 316L stem, HNBR seats DN 25–DN 600 V-031 Ex-stock
Ball Valve (Trunnion) API 6D WCB, WC6 Duplex 2205 stem, PTFE seats DN 50–DN 600 V-034 Ex-stock
Check Valve (Swing) API 6D WCB, WC9 (A217) 13Cr disc/seat DN 50–DN 600 V-027 Ex-stock
Globe Valve API 623 WCB 13Cr plug/seat (NACE trim) DN 25–DN 300 V-028 Ex-stock
Butterfly Valve (HF) API 609 WCB HF disc, PTFE seat DN 200–DN 1200 V-038 On order

All valves are NACE MR0175 / ISO 15156 compliant at time of supply. SAEP-347 material numbers shown are indicative — verify current Annex 3 with latest SAEP-347 revision. FTF = full bore, face-to-face per API 6D. HF = Hardfacing (stellite or equivalent).

In Summary

All five SAEP-347 sour service valve types — ball, gate, globe, check, and butterfly — can be supplied with NACE MR0175 compliance. Key requirements: body and bonnet hardness must not exceed 22 HRC (Rockwell C scale) for carbon steel castings; trim materials (stem, seats, wedge) must also comply; and low-alloy steel bodies (WC6/WC9) require post-weld heat treatment (PWHT). Carbon steel WCB and stainless steel CF8M are the most commonly specified sour-service valve body materials at Gulf Union Ozone.

Material Selection Guide

Valve Body Material Selection for Sour Service — Carbon Steel vs Alloy

Body Material ASTM Spec Temp Range Sour Service Typical Use
WCB A216 Gr. WCB -29°C to 427°C NACE compliant (normalized) General sour service utility piping
WCC A216 Gr. WCC -29°C to 427°C NACE compliant (normalized) Higher strength than WCB for heavier service
WC6 A217 Gr. WC6 -29°C to 593°C NACE compliant (PWHT required) High-temp sour process — steam, gas
WC9 A217 Gr. WC9 -29°C to 649°C NACE compliant (PWHT required) Hydrocracker, reformer, high-temp sour
LCC A352 Gr. LCC -46°C to 345°C NACE compliant (QT) Cold climate sour service, LNG upstream
CF8M A351 Gr. CF8M (316SS) -196°C to 816°C Not recommended for SSC service Non-sour corrosive service only

CF8M (316 stainless) is NOT permitted in wet H₂S sour service per NACE MR0175 — it is susceptible to SSC. NACE MR0175 Part 3 governs austenitic stainless steels and allows some grades but excludes cold-worked 316SS. For sour service requiring corrosion resistance, specify duplex 2205 (A890 Grade 4A) or super duplex 2507 per Aramco piping class.

Stock & RFQ

Order Sour Service Valves — Required Information

8 Items to Include in Every Sour Service Valve RFQ
  1. Valve type: gate / ball / check / globe
  2. Size: DN or NPS
  3. Pressure rating: Class 150–2500 or PN 16–400
  4. Body material: WCB / WC6 / WC9 / LCC
  5. Trim: 13Cr NACE trim (or specify alternative)
  6. End connections: flanged (RF/RTJ) or BW
  7. Confirm sour service: H₂S partial pressure or total H₂S content
  8. SAEP-347 material number (if known from engineering BOM)
Documentation Package (NACE Service)
  • EN 10204 3.1 MTC — body, bonnet, bolting, stem
  • Hardness test certificate (Brinell + Rockwell per piece)
  • NACE MR0175 / ISO 15156 compliance statement from mill
  • Heat treatment certification (normalization / PWHT)
  • Third-party inspection (TPI) report if required by project spec
RFQ Sample — Sour Service Gate Valve
Valve type: Gate valve
Standard: API 600 / API 6D
Size: 8" NPS (DN 200)
Class: 600 (ANSI/ASME)
Body: A216 WCB (NACE normalized)
Trim: 13Cr (NACE trim)
Ends: Flanged RF
Sour service: Yes — H₂S service
Hardness: 22 HRC max required
MTC: EN 10204 3.1
SAEP-347: V-025
Qty: 4 pieces
Request Sour Service Valve Quote
FAQ

NACE MR0175 Sour Service Valve Questions — Answered

What hardness limit does NACE MR0175 specify for valves in H₂S sour service?

NACE MR0175 / ISO 15156 specifies a maximum hardness of 22 HRC (Rockwell C-scale) or 250 HBW (Brinell) for carbon steel and low-alloy steel valve components in H₂S sour service. This applies to all load-bearing components — body, bonnet, bolting, stem, and disc/ball. Saudi Aramco SAEP-347 enforces this through Annex 3 material numbers and requires production hardness testing with results documented on EN 10204 3.1 MTCs. Hardness is the most critical NACE MR0175 parameter for valves — it must be tested per piece, not per heat/lot.

Can I use a standard API 600 gate valve for sour service, or do I need a special version?

A standard API 600 gate valve in WCB body may or may not be NACE MR0175 compliant — it depends on the heat treatment and the specific hardness readings of that production batch. API 600 valves for sour service must be explicitly specified as 'NACE compliant' and supplied with normalized body material (not as-cast), per-piece hardness test certification showing ≤22 HRC on all load-bearing components, a NACE MR0175 trim package (13Cr stem, NACE bolting to A193 B7M/A194 2HM), and an EN 10204 3.1 MTC explicitly referencing NACE compliance. Gulf Union Ozone supplies API 600 gate valves pre-certified to NACE MR0175 with full documentation. Do not procure standard (non-NACE) API 600 valves and assume they comply — you must verify each certificate.

Why is 316 stainless steel not recommended for sour service valve bodies?

NACE MR0175 / ISO 15156 Part 3 restricts the use of austenitic stainless steels in sour service based on hardness and cold work state. 316 stainless steel (CF8M or A182 F316) can meet NACE MR0175 requirements IF it is in the solution-annealed condition and has hardness below 22 HRC. However, any cold work — machining, forming, or cold straightening — can raise local hardness above the limit and trigger SSC. Saudi Aramco piping classes specify duplex 2205 or super duplex 2507 for sour service applications requiring corrosion resistance, as these alloys have significantly better resistance to both SSC and HIC than austenitic stainless steels.

Related Resources

Further Reading

Product Hub
All Industrial Valves — Saudi Arabia
Gate, ball, check, butterfly, globe, control valves — all types from Jeddah stock.
Valve Spec
API 600 Gate Valves — SAEP-347
WCB/WC6/WC9 gate valves with body material options, trim comparison, and SAEP-347 material numbers.
Valve Spec
API 6D Ball Valves — NACE MR0175 Compliant
Full-bore API 6D ball valves with NACE MR0175 hardness certification for H₂S sour service — SAEP-347 material numbers stocked.
Technical Guide
Sour Service Materials — Full Guide
NACE MR0175 compliant valves, pipes, fittings, and flanges — complete material selection for all piping components.
Technical Guide
SAEP-347 Explained — What It Means for Valve Buyers
Saudi Aramco's approved stockist program — what SAEP-347 approval means and how to verify supplier status.
✓ISO 9001:2015 Certified
✓SAEP-347 Approved Stockist
✓NACE MR0175 Hardness Certified
✓EN 10204 3.1 MTCs on Every Order
Get a Quote

Request NACE MR0175 Sour Service Valves — Jeddah Ex-Stock

Include valve type, size, pressure class, body material, trim, service conditions, and SAEP-347 material number. We confirm hardness certification availability and pricing within 4 business hours. Standard API 600 NACE-compliant gate valves in Class 150–900 ship same-day from Jeddah.

Submit RFQ Online