Carbon steel pipe flange and low-alloy steel flanges are the most widely used connecting components in industrial piping systems, applied in oil & gas, petrochemicals, power generation, shipbuilding, water treatment, construction, and mechanical engineering. Manufactured from high-quality carbon or low-alloy structural steels through forging, heat treatment, and precision machining, these flanges offer excellent mechanical strength, weldability, and cost-effectiveness, serving as critical elements for reliable connections in medium- and high-pressure piping systems.
Key Features
Standards:
International Standards:
ASME B16.5 (Pipe Flanges and Flanged Fittings)
ASME B16.47 (Large Diameter Steel Flanges, Series A & B)
MSS SP-44 (Steel Pipeline Flanges)
API 6A (Wellhead Equipment Flanges)
EN 1092-1 (European Steel Flange Standard)
Domestic Standards:
GB/T 9112–9128 (Steel Pipe Flanges)
HG/T 20592–20635 (Chemical Industry Flange Standards)
SH/T 3406 (Petrochemical Steel Flanges)
JB/T 74–90 (Mechanical Industry Flange Standards)
Materials:
Carbon Steel Flanges:
ASTM A105 (Forged Carbon Steel for General Service)
Q235, Q345B (Chinese standards, for non-pressure or low-pressure systems)
ST37, ST52 (German DIN 17100 standards)
Low-Alloy Steel Flanges:
ASTM A181 Gr. 60/70 (General Purpose)
ASTM A350 LF2 (Low-Temperature Service, -46°C impact tested)
ASTM A350 LF3 (-101°C application)
16Mn, 15CrMo, 12Cr1MoV (for high-temperature/high-pressure service)
All materials meet chemical and mechanical requirements of respective standards, with heat treatment reports provided.
Dimensions:
Nominal Diameter (DN): DN15 (1/2") to DN2000 (80") or large size flanges
Pressure Classes: Class 150, 300, 600, 900, 1500, 2500 (ASME)
Connection Types: Weld Neck (WN), Slip-On (SO), Socket Weld (SW), Threaded (TH), Lap Joint (LJ)
Face Types: Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ), Male-Female (MF), Tongue & Groove (TG)
Applications:
Carbon Steel Flanges: Suitable for ambient temperature and medium/low-pressure environments, such as:
Building water supply and drainage
General industrial piping
Ship auxiliary systems
Water treatment equipment
Low-Alloy Steel Flanges: Used in high-temperature, low-temperature, or high-pressure environments, such as:
Oil refining units (high-temp lines)
LNG cryogenic pipelines (LF2/LF3 materials)
Power plant steam systems (15CrMo)
Offshore platform process lines
Certifications & Approvals:
Classification Society Certifications:
ABS, DNV, LR, BV, NK, CCS,NORSOK M650
Provide Type Approval Certificates and Mill Test Certificates + Third-Party Inspection Reports per batch
Owner & Engineering Company Approvals:
ISO 9001 Quality Management System
API 6A Certification (for oil & gas wellhead equipment)
PED 2014/68/EU (Pressure Equipment Directive)
AD 2000-Merkblatt (German pressure vessel code)
Approved by GE,ADNOC,CNPC, Sinopec, CNOOC, Shell, ExxonMobil, Total, etc.
Common Customer Questions (Q&A Format)
Q: What is the main difference between carbon steel and low-alloy steel flanges?
A: Carbon steel flanges are cost-effective for normal conditions; low-alloy steels contain Cr, Mo, Ni, offering higher strength, temperature, or low-temperature resistance for severe service.
Q: How to select the right flange material?
A: Choose based on temperature, pressure, medium, and environment:
Ambient conditions: A105 or Q235;
Low-temp (-46°C): A350 LF2;
High-temp (>400°C): 15CrMo or A182 F11.
Q: Do you support non-standard flange designs?
A: Yes, custom designs based on customer drawings or ASME B16.5/EN 1092-1, with FEA analysis support.
Q: What are the heat treatment conditions?
A: Carbon steel: Typically normalized or annealed;
Low-alloy steel: Usually normalized & tempered for improved toughness.
Q: Are NDT services available?
A: Yes, MT, UT, PT available upon request, especially for Class 600+ or low-temperature flanges.
Q: How are flange sealing surfaces protected during shipping?
A: RF faces with plastic guards, RTJ faces secured in wooden crates, overall packed in moisture-proof film + steel frame to prevent damage and corrosion.
Q: Do your flanges comply with PED?
A: Yes, for EU markets, we provide CE marking per PED 2014/68/EU, including material traceability, design validation, and third-party inspection.
Q: What is the lead time?
A: Standard products: 15–30 days; non-standard or large-diameter: 45–90 days, depending on material, quantity, and heat treatment.
Q: How is dimensional accuracy ensured?
A: CNC machining with tolerances within ±0.1mm, supported by CMM reports.
Q: Is material traceability provided?
A: Yes, each batch includes a Material Test Certificate (MTC 3.1 or 3.2) with heat number, chemical composition, mechanical properties, and heat treatment records for full lifecycle traceability.
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