Slip On Flange (SO Flange) | Raised Face & RTJ Slip On Pipe Flanges

 

What Is a Slip On Flange?

A Slip On Flange (SO Flange) is a type of pipe flange designed to slide over the end of a pipe before welding. The internal diameter of the flange is slightly larger than the outside diameter of the pipe, allowing the flange to easily slip onto the pipe before welding.

After positioning, the flange is fillet welded both inside and outside to ensure a secure connection and proper sealing.

Slip-on flanges are widely used in low to medium pressure piping systems because of their easy installation, cost-effectiveness, and reliable performance.

Common industries using SO flanges include:

• Oil and gas pipelines

• Chemical processing plants

• Water treatment systems

• Power plants

• Petrochemical facilities

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Key Features of Slip On Flanges

 

Simple Design

Slip-on flanges feature a flat face design and are installed by sliding the flange over the pipe before welding.

Easy Installation

Because the flange slides over the pipe, installation is easier compared with other flange types such as weld neck flanges, which require precise alignment.

Cost-Effective

Slip-on flanges are typically less expensive than weld neck flanges, making them a popular choice for many piping systems.

Reliable Sealing

With both internal and external welds, slip-on flanges provide reliable sealing performance for low and medium pressure applications.

Wide Material Options

Slip-on flanges can be manufactured from a wide range of materials including:

• Carbon steel

• Stainless steel

• Alloy steel

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Slip On Flange Specifications

Manufacturing Standards

• ASME B16.5 – American Standard Pipe Flanges

• EN 1092-1 – European Standard Steel Flanges

• DIN – German Standard Flanges (DIN 2576 / DIN 2633 / DIN 2635 / DIN 2642)

• JIS B2220 – Japanese Industrial Standard Flanges

• GOST 33259 / GOST 12820 – Russian Standard Pipe Flanges

Materials

• Carbon Steel: ASTM A105, A350 LF2

• Stainless Steel: ASTM A182 F304, F304L, F316, F316L

• Alloy Steel: ASTM A182 F11, F22

Size Range

• Standard Size: 1/2″ – 24″

• Custom Size: Up to 60″

Pressure Rating

ASME Standard

• Class 150

• Class 300

• Class 600

• Class 900

• Class 1500

• Class 2500

EN / DIN Standard

• PN6

• PN10

• PN16

• PN25

• PN40

• PN63

• PN100

JIS Standard

• 5K

• 10K

• 16K

• 20K

GOST Standard

• PN10

• PN16

• PN25

• PN40

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Types of Slip On Flanges

Raised Face Slip On Flange (RF)

A Raised Face Slip On Flange includes a small raised area on the flange face where the gasket is installed. This design improves sealing performance for most industrial piping systems.

As the pressure rating increases, the height of the raised face also increases.

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RTJ Slip On Flange (Ring Type Joint)

An RTJ Slip On Flange contains a precision-machined groove designed to hold a metal ring gasket.

This type of flange is typically used in:

• High pressure systems

• High temperature pipelines

• Oil and gas applications

Compared with RF flanges, RTJ flanges provide stronger sealing performance.

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Manufacturing Methods

Slip-on flanges can be produced using several manufacturing methods:

• Forging

• Steel plate cutting

• Casting

Among these processes, forged slip-on flanges provide the highest quality and strength, and are the most commonly used in industrial piping systems.

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Advantages of Slip On Flanges

• Lower installation costs

• Easy pipe alignment during installation

• Suitable for low and medium pressure systems

• Inner and outer welding improves sealing

• Faster installation compared with some other flange types

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Slip On Flange vs Weld Neck Flange

Slip-on flanges and weld neck flanges are both widely used in piping systems, but they differ in strength and application.

The internal pressure strength of a Slip On Flange is approximately two-thirds that of a Weld Neck Flange, and its service life is typically shorter.

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Slip On Flange Applications

Slip-on flanges are widely used in various industrial piping systems, including:

Oil and Gas Industry

• Pipeline connections

• Refinery piping systems

Water Treatment Plants

• Water supply pipelines

• Pump and valve connections

Chemical Processing

• Chemical transport pipelines

• Process piping systems

Power Generation

• Cooling water systems

• Steam pipelines

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Slip On Flange Supplier

We are a professional manufacturer and exporter of Slip On Flanges (SO Flanges) for global industries.

Our supply advantages include:

• Wide range of materials and sizes

• Strict quality inspection

• Competitive factory pricing

• Custom flange manufacturing

• Global export packaging

All products are supplied with EN 10204 3.1 Mill Test Certificate.

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FAQ – Slip On Flange

What is a slip on flange?

A Slip On Flange (SO flange) is a pipe flange that slides over the pipe and is welded inside and outside to secure the connection.

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What is the difference between slip on flange and weld neck flange?

Slip-on flanges are easier and cheaper to install, but weld neck flanges provide higher strength and better performance in high-pressure systems.

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Where are slip on flanges used?

Slip-on flanges are commonly used in low to medium pressure piping systems such as water pipelines, oil pipelines, and chemical processing systems.