The slip on flange (SO flange) is a widely used pipe flange designed to slide over the pipe and be fillet welded both inside and outside, ensuring a secure and leak-resistant connection in pipeline systems.
It is one of the most cost-effective flange types for low to medium pressure applications in industrial piping and EPC engineering projects.
Compared with weld neck flanges, slip on flanges offer easier alignment, faster installation, and lower machining cost, making them highly suitable for large pipeline construction and international engineering projects.
Our slip on flanges are manufactured for global pipeline systems across Europe, the Middle East, and Central Asia, where dimensional accuracy, standard compliance, and stable supply are critical for oil & gas and energy infrastructure projects.
Easy installation and alignment during pipeline construction
Double fillet welding for enhanced sealing performance
Cost-effective solution for medium and low-pressure systems
Available in large diameter and custom specifications
Compatible with international flange standards
Stable performance in industrial and energy pipeline systems
Supplied with EN10204 3.1 / 3.2 Mill Test Certificate upon request
| Specification | Range |
| Nominal Diameter | DN15 (1/2") – DN3000 (120") |
| Pressure Class | Class 150 – Class 2500 |
| Facing Type | RF / FF / RTJ |
| Standard | ASME B16.5 / ASME B16.47 / EN / DIN |
| Wall Compatibility | SCH 10 – SCH XXS |
| Coating | Anti-rust Oil / Black Painting / Galvanized / FBE |
These slip on flanges are suitable for large-scale pipeline engineering projects and industrial piping systems requiring reliable and economical flange connections.
Our SO flanges are manufactured in strict accordance with international flange standards to ensure compatibility with global pipeline systems and EPC project requirements:
ASTM Standards:
ASTM A105, A350, A694, A182, A240
ASME / ANSI Standards:
ASME B16.5
ASME B16.47 Series A & B
EN Standards (Europe Market):
EN 1092-1 Type 01
DIN Standards:
DIN 2573, DIN 2576, DIN 2631–2635
API Standard (Oil & Gas Projects):
API 6A (When Required)
JIS Standards (International Projects):
JIS B2220
Multi-standard manufacturing ensures seamless use in Europe, Middle East, and Central Asia pipeline and refinery projects.
ASTM A105
ASTM A350 LF2
ASTM A694 F42 / F52 / F60 / F65 / F70
DIN P235GH / P265GH
ASTM A182 F304 / F304L
F316 / F316L / F321 / F347
EN 1.4301 / 1.4404
ASTM A182 F11 / F22 / F5 / F9 / F91
ASTM A182 F51 / F53 / F55
Inconel / Monel / Hastelloy (Available on Request)
All materials are fully traceable and supplied with Mill Test Certificates (MTC).
To ensure high strength and dimensional precision, each slip on flange is produced through a strict manufacturing process:
Raw material inspection & chemical verification
Cutting and forging / rolling
Heat treatment (normalizing / quenching & tempering)
CNC machining and drilling
Facing machining (RF / RTJ / FF)
Dimensional inspection
NDT testing (UT / PMI / RT if required)
Surface treatment and marking
This process guarantees excellent mechanical properties and long service life in industrial pipeline systems.
Every slip on flange undergoes strict quality inspection procedures:
100% Dimensional Inspection
Chemical Composition Analysis (PMI)
Ultrasonic Testing (UT)
Radiographic Testing (RT)
Hardness Testing
Visual & Surface Inspection
All inspections comply with ASTM, ASME, EN, and EPC project specifications.
Oil & Gas pipeline systems
Petrochemical and refinery plants
Power plant piping systems
Water treatment pipelines
Offshore & onshore pipeline projects
LNG and energy infrastructure
Industrial fluid and process pipelines
Especially suitable for EPC contractors, refinery projects, and pipeline construction projects in the Middle East, Europe, and Central Asia.
Manufacturer direct supply for EPC & project contractors
Full size range from 1/2” to 120”
Multi-standard production (ASME / EN / DIN)
Competitive price compared to weld neck flanges
Stable export quality for oil & gas projects
Fast delivery for urgent pipeline projects
Rich export experience in Middle East & European markets
Q1: What is a slip on flange used for?
A: A slip on flange is used to connect pipes in low to medium pressure pipeline systems, commonly applied in oil & gas, petrochemical, and industrial piping projects.
Q2: What is the difference between slip on flange and weld neck flange?
A: Slip on flanges are easier to install and more cost-effective, while weld neck flanges provide higher strength for high-pressure and critical applications.
Q3: Do you supply slip on flanges for EPC and international projects?
A: Yes, we supply SO flanges for EPC, refinery, and pipeline projects across Europe, the Middle East, and Central Asia.
Q4: Can you provide custom size and coating?
A: Yes, we support custom dimensions, drilling, coating (FBE, galvanizing), and project-specific specifications.
