NACE Sour Service Forged Flanges for H₂S Oil & Gas Applications
Product Overview
GS Pipeline is a professional manufacturer and exporter of NACE sour service forged flanges engineered for critical oil & gas applications containing hydrogen sulfide (H₂S).
Our sour service flanges are manufactured according to NACE MR0175 / ISO 15156 requirements, with strict control of chemical composition, heat treatment, hardness limits, and mechanical properties to prevent:
- Sulfide Stress Cracking (SSC)
- Hydrogen Induced Cracking (HIC)
- Stress Corrosion Cracking (SCC)
These forged flanges are widely used in:
- Oil and gas production facilities
- Sour gas pipelines
- Refineries
- Petrochemical plants
- Offshore platforms
- Natural gas processing systems
- Hydrogen sulfide environments
GS Pipeline supplies NACE compliant forged flanges with complete documentation including MTR, EN10204 certificates, PMI inspection, hardness testing, and NACE compliance reports.
Product Features
High Resistance Against H₂S Corrosion
NACE sour service flanges are designed for environments where hydrogen sulfide can cause severe material degradation.
Special manufacturing controls ensure:
- Reduced susceptibility to SSC
- Improved hydrogen resistance
- Stable mechanical performance under pressure
- Long service life in sour environments
Strict Hardness Control
Hardness control is one of the most important requirements for sour service applications.
Typical hardness limits:
| Material Type | Maximum Hardness |
| Carbon Steel | ≤ 22 HRC |
| Low Temperature Carbon Steel | ≤ 22 HRC |
| Stainless Steel | ≤ 28 HRC |
| Duplex Stainless Steel | ≤ 32 HRC |
All finished products undergo hardness inspection according to customer requirements.
Controlled Chemical Composition
To improve sour service performance, materials are manufactured with controlled alloy chemistry.
Typical requirements:
| Element | Requirement |
| Carbon (C) | ≤ 0.10% |
| Phosphorus (P) | ≤ 0.020% |
| Sulfur (S) | Controlled according to NACE requirements |
| Carbon Equivalent (CE) | ≤ 0.43 |
Low impurity levels reduce the risk of cracking in H₂S environments.
Applicable Standards
GS Pipeline NACE forged flanges comply with international standards:
Flange Manufacturing Standards
- ASME B16.5
- ASME B16.47 Series A / Series B
- API 6A
- ISO 7005
- MSS SP-44
Sour Service Standards
- NACE MR0175
- ISO 15156
- NACE TM0177 SSC Test
- NACE TM0284 HIC Test
Material Standards
- ASTM
- ASME SA Standards
- EN10204 Certification
Sour Service Forged Flange Material Grades
Carbon Steel Sour Service Flanges
ASTM A105N NACE
Applications:
- Oil pipelines
- Pressure vessels
- Refinery piping systems
Features:
- Normalized forging
- Controlled hardness
- Low sulfur and phosphorus content
- Suitable for sour environments
Low Temperature Carbon Steel
ASTM A350 LF2 NACE
Features:
- Excellent impact toughness
- Suitable for low temperature sour service
- Used in offshore and gas processing systems
Hardness:
≤22 HRC
Stainless Steel Sour Service Flanges
ASTM A182 F304 / F304L
Applications:
- Chemical processing
- Corrosive gas systems
- Offshore facilities
Features:
- Excellent corrosion resistance
- Good resistance against chloride environments
ASTM A182 F316 / F316L
Features:
- Improved corrosion resistance
- Suitable for marine and chemical applications
- Better chloride resistance
Duplex Stainless Steel Sour Service Flanges
ASTM A182 F51 Duplex 2205
Features:
- High mechanical strength
- Excellent chloride resistance
- Good SSC resistance
ASTM A182 F53 Super Duplex 2507
Features:
- Extreme corrosion resistance
- Offshore application suitable
- High pressure sour gas service
Product Range
Forged Flange Types
GS Pipeline manufactures complete NACE forged flange solutions:
Weld Neck Flanges (WN)
Advantages:
- High pressure capability
- Excellent stress distribution
- Suitable for pipelines and pressure vessels
Slip On Flanges (SO)
Applications:
- General industrial piping
- Low to medium pressure systems
Blind Flanges (BL)
Applications:
- Pipeline isolation
- Pressure testing systems
Socket Weld Flanges (SW)
Applications:
- Small diameter high pressure piping
Threaded Flanges
Applications:
- Non-welded piping systems
Lap Joint Flanges
Applications:
- Corrosion resistant piping systems
Size & Pressure Range
Standard Dimensions
| Parameter | Range |
| Size | 1/2″ – 60″ |
| Pressure Class | 150LB – 2500LB |
| Facing | RF / FF / RTJ |
| Manufacturing | Forged |
| Connection | ASME, API, Custom |
Flange Facing Options
Raised Face (RF)
Most common flange facing type for:
- Oil & gas pipelines
- Refineries
- Chemical plants
Flat Face (FF)
Used for:
- Cast equipment connections
- Low pressure systems
Ring Type Joint (RTJ)
Recommended for:
- High pressure sour gas service
- API applications
- Offshore platforms
Manufacturing Process
GS Pipeline controls every production stage:
1. Material Selection
Certified NACE approved raw materials are selected.
2. Forging Process
Controlled forging improves:
- Grain structure
- Mechanical strength
- Fatigue resistance
3. Heat Treatment
Processes include:
- Normalizing
- Quenching and tempering
- Solution treatment
4. Machining
Precision machining ensures:
- Accurate dimensions
- Proper sealing performance
- International standard compliance
5. Inspection
Final inspection includes:
- Dimensional inspection
- Hardness testing
- PMI testing
- Mechanical testing
Sour Service Testing & Documentation
GS Pipeline provides complete quality documentation.
Available Tests
SSC Test
According to:
NACE TM0177
Purpose:
Verify resistance against sulfide stress cracking.
HIC Test
According to:
NACE TM0284
Purpose:
Evaluate hydrogen-induced cracking resistance.
PMI Test
Positive Material Identification ensures correct alloy grade.
Documentation Package
Available documents:
- Mill Test Certificate (MTR)
- EN10204 3.1 Certificate
- EN10204 3.2 Certificate
- NACE Compliance Letter
- Hardness Test Report
- Chemical Analysis Report
- Mechanical Test Report
- Inspection Report
Applications
NACE sour service forged flanges are widely used in:
Oil & Gas Industry
- Sour crude oil pipelines
- Gas gathering systems
- Wellhead equipment
- Production facilities
Petrochemical Industry
- Refinery piping
- Hydrogen sulfide processing units
- Chemical reactors
Offshore Engineering
- Offshore platforms
- Subsea pipelines
- Marine energy systems
Power Industry
- Gas-fired power plants
- Hydrogen-related systems
Why Choose GS Pipeline NACE Flanges?
Professional Manufacturing Capability
GS Pipeline provides:
- Forged flange production
- International standard manufacturing
- Export experience
- Customized solutions
Quality Assurance
Benefits:
✔ NACE compliant materials
✔ Full traceability
✔ Strict hardness control
✔ Third-party inspection support
✔ Worldwide export packaging
Global Supply Capability
We support customers from:
- USA
- Canada
- Middle East
- Southeast Asia
- Europe
- Africa
- South America
Custom NACE Flange Manufacturing
GS Pipeline can manufacture customized sour service flanges according to:
- Customer drawings
- API specifications
- Project requirements
- EPC contractor specifications
Customization options:
- Special dimensions
- Large diameter flanges
- Special materials
- RTJ groove machining
- Third-party inspection
Frequently Asked Questions (FAQ)
What is a NACE sour service flange?
A NACE sour service flange is a pressure flange manufactured according to NACE MR0175 / ISO 15156 requirements for environments containing hydrogen sulfide (H₂S).
What hardness is required for NACE carbon steel flanges?
Carbon steel sour service flanges normally require hardness control of ≤22 HRC.
What materials are suitable for sour gas applications?
Common materials include:
- A105N NACE
- A350 LF2 NACE
- F316L
- Duplex 2205
- Super Duplex 2507
Do you provide NACE test certificates?
Yes. GS Pipeline provides:
- SSC testing
- HIC testing
- PMI reports
- EN10204 certificates
- NACE compliance documentation
Can you supply API 6A sour service flanges?
Yes. GS Pipeline manufactures API 6A compatible forged flanges for oilfield and wellhead applications.
Request a Quote for NACE Sour Service Forged Flanges
Looking for reliable NACE MR0175 / ISO 15156 sour service forged flange suppliers?
Contact GS Pipeline for:
- Technical consultation
- Material selection support
- Project quotations
- Customized flange solutions
GS Pipeline – Professional Manufacturer of NACE Sour Service Forged Flanges for Global Oil & Gas Applications.