Slip on Flange

Slip on flanges

Slip on flanges, also called SO flanges, are a popular type of pipe flange designed to accept pipe into the bore/center of the flange for welding around both the Outer Diameter (OD) of the pipe and on the interior side of the connection.

The slip-on flange is a straightforward alternative to a weld neck flange, offering flexibility in adjusting the pipe length relative to the flange’s position due to its lack of a weld bevel. This design provides ample clearance for the pipe and facilitates easier welding and fabrication.

Primarily used in lower pressure applications, slip-on flanges typically feature a hub that resembles a raised face but can also be supplied in a "ring style" without a hub if space constraints demand it. While the hub style is more prevalent, the ring style is also valid within the slip-on category. For higher pressure applications, slip-on flanges may be manufactured with a lap joint height for improved connection quality. In cases where a lap joint is unavailable or the hub height is not critical, a slip-on flange can be produced with a machined hub to resemble a lap joint style.

In general, slip-on flanges are less suitable for high-stress applications compared to weld neck flanges. The latter features a reinforced hub and a tapered weld bevel, providing a more robust connection to the pipe’s butt weld end, which is better suited for environments subject to significant mechanical stress.

Midas is a leading manufacturer of slip-on flanges in China, offering Slip On Flanges that meet various standards including ANSI, MSS, AWWA, DIN, UNI, JIS, BS, SABS, EN1092, and GOST, as well as custom designs based on customer specifications. Our slip-on flanges are available in sizes ranging from 15mm to 2,000mm and can feature flange facings such as RF, FF, and RTJ. We provide flanges in materials like carbon steel, stainless steel, and alloy steel, with manufacturing processes including forging or casting. For protection and durability, we offer painting options such as yellow, black, anti-rust oil, or zinc coating, and pack our products in sea-worthy plywood cases or pallets with polyethylene film, tailored to customer requirements.

Types of Slip On Flange Welding

Slip-on flanges come in two main types: the slip-on welding plate flange and the slip-on welding hubbed steel pipe flange. These flanges offer mechanical properties that fall between those of integral flanges and looping flanges, featuring a straightforward design and ease of processing. As a result, slip-on flanges are commonly utilized in various fluid pipeline systems.

Slip-on flanges come in several types based on the flange face design, including Raised Face (RF), Ring-Type Joint (RTJ) and Flat Face (FF).

Raised Face Slip On Flange:

The raised face slip-on flange features a small protrusion on its bottom face. This raised face serves as a designated area for gasket placement during installation, enhancing the overall sealing performance.

RTJ Slip on Flange (Ring-Type Joint):

The RTJ slip-on flange features a machined groove on the raised face, designed to accommodate a gasket ring for effective sealing. This RTJ design is specifically intended for high-pressure applications, offering a more robust sealing solution compared to the RF type. The groove allows for a secure placement of the gasket, enhancing the flange’s ability to withstand elevated pressures.

Slip on flange use slip welding to connect equipment, so either below of name is describing the same flange:

1. Slip on weld flange

2. Slip on flange weld

3. Weld slip on flange

4. Slip on flange welding

5. SO flange

FF Slip-On Flange: 

The FF (Flat Face) slip-on flange has a flat, unraised sealing surface, which contacts the gasket directly. This type is often used in lower pressure applications and is preferred when a more uniform seal is needed across the flange face.

Faq

1. Advantages of Slip-On Flange

Lower Installation Costs: Slip-on flanges generally require less material and fewer manufacturing steps compared to other types of flanges, such as weld neck flanges. This simplicity results in reduced production and installation costs. The absence of a weld bevel also means that fewer preparatory steps are needed, further lowering overall expenses.

Easier Alignment During Installation: Slip-on flanges are designed to slide over the pipe, allowing for straightforward alignment with other components. This ease of alignment simplifies the installation process, reducing the time and effort needed to ensure that all parts fit together correctly.

Improved Leak Proofing: While slip-on flanges are not inherently leak-proof, their design facilitates better sealing when used with appropriate gaskets. The ability to weld both inside and outside the flange helps to secure the joint, minimizing the risk of leaks compared to flanges that only allow for external welding.

Inner and Outer Welding on Flange: Slip-on flanges support welding both inside the flange bore and on the outer surface. This dual welding provides additional strength and enhances the seal, making the connection more robust and reliable, especially in applications where joint integrity is crucial.

Faster Accurate Cutting for Pipelines: The design of slip-on flanges simplifies the cutting process for pipelines. Since the flange slides over the pipe, it is easier to achieve precise cuts and alignments, saving time during the preparation and installation stages.

Compatibility with Lower Hub: Slip-on flanges are designed to accommodate pipes sliding onto them, which means they are compatible with flanges that have a lower hub. This feature is beneficial in installations where space is limited or where a lower hub design is required for specific engineering or design constraints.

2. How are slip-on flanges installed?

To install a slip-on flange, slide it over the end of the pipe, align it with the mating flange or component, and then weld it both inside and outside the flange. Proper alignment and welding ensure a secure and leak-proof connection.

3. What is the difference between a slip-on flange and a weld neck flange?

A slip-on flange slides over the pipe and is welded externally and internally, making it easier and less costly to install. In contrast, a weld neck flange has a tapered neck that is welded directly to the pipe, providing a stronger and more durable connection, particularly for high-pressure and high-temperature applications.

4. Can slip-on flanges be used for high-pressure applications?

Slip-on flanges are typically used in lower to moderate pressure applications. For high-pressure environments, other flange types such as weld neck flanges or RTJ flanges are generally recommended due to their superior strength and sealing capabilities.

5. How do you ensure a leak-proof seal with slip-on flanges?

To achieve a leak-proof seal, it is crucial to use appropriate gaskets and ensure that the flange is welded properly both inside and outside. Regular inspection and maintenance can also help in maintaining the integrity of the seal.

6. Are slip-on flanges available in custom sizes and specifications?

Yes, slip-on flanges can be manufactured to custom sizes and specifications based on customer requirements. Manufacturers can produce flanges in various dimensions, materials, and face types to meet specific project needs.

7. What are the common applications for slip-on flanges?

Slip-on flanges are commonly used in water and wastewater systems, general industrial pipelines, and low to moderate pressure applications. Their ease of installation and cost-effectiveness make them a popular choice for many piping systems.