slip-on /SO flange

What is a slip-on flange?

Slip-on flanges, also known as ‘hubbed flanges’, have a hub with a very low profile. This slip-on flange is usually connected to a pipe by one or two fillet welds (one outside the flange and one inside the flange), it is, however, possible to use only a single weld.
The connection is typically secured with two fillet welds—one on the outer and one on the inner side of the flange. For less critical applications, a single external weld can suffice. This welding method, however, does not create a full-penetration bond, which makes slip-on flanges the ideal choice for lower-pressure and lower-risk environments. Their design makes them a common sight in utility lines for cooling water, firefighting, low-pressure compressed air, and process lines carrying substances like steam, oil, and gas.

A key design feature of a slip-on flange is its internal diameter, which is slightly larger than the pipe’s outer diameter, enabling the “slip-on” fit. While their weld integrity is lower than that of a welding neck flange, they offer a significant advantage in tight spaces. However, if a welding neck flange cannot be used due to space limitations, a slip-on flange may be a suitable alternative.

When you need a robust and dependable connection, quality is non-negotiable. Our slip-on (SO) flanges are designed to slide over the pipe and be welded securely, creating a lasting seal. Every flange we supply conforms to the rigorous ASME B16.5 and B16.47 standards, ensuring your system meets critical safety and operational requirements.

Key Features:

1. Material: High-quality steel that ensures durability and resistance to corrosion.
2. Sizes: Available in a range of sizes to fit different pipe diameters. Custom sizes can also be created upon request.
3. Standards: Manufactured according to ASME B16.5 and B16.47 standards, guaranteeing quality and compatibility with various pipe fittings.
4. Ease of Installation: Slides easily over the pipe and secures with welding, providing a robust and reliable connection.
5. Applications: Ideal for use in lower pressure applications and suitable for industries such as petrochemical, oil & gas, water treatment, and more.

We deliver Slip On flanges in the following material grades:

Slip-on flanges are manufactured to meet various global standards and systems.

Choosing the Right Type of Slip-On Flange for Your Project

SO flanges are available in two primary designs, each engineered to solve specific challenges within a piping system:

1. Standard (Raised Face) Slip-On Flanges

This is the most common type, featuring a “raised face” on the sealing surface. This slightly elevated platform is crucial because it concentrates the bolt-tightening pressure onto the gasket, creating an exceptionally reliable seal. This design is highly effective and recommended for low-pressure systems where preventing leaks is a top priority.

2. Lap Joint Slip-On Flanges

The lap joint configuration consists of a flat-faced flange that works with a separate backing flange and a lap joint stub end. After the stub end is welded to the pipe, the backing flange can slide and rotate freely. This clever design offers unmatched flexibility, simplifying the alignment of bolt holes during installation or maintenance. It’s the perfect solution for systems that require frequent dismantling or those that experience thermal expansion and contraction.

Slip-On Flanges Industrial Applications

Trust JSFITTINGS for Industry-Leading Flanges!

At JSFITTINGS, we are an industry-leading supplier offering an extensive selection of slip-on pipe flanges in various steel grades, including carbon, stainless, and alloy.
Our well-stocked inventory eliminates frustrating sourcing delays, ensuring you get the flanges you need without putting your project on hold. Combined with our efficient and reliable shipping, you can be confident that your materials will arrive on-site, on time.
Contact us today to learn more about our products, or request a no-obligation quote now!

FAQs

Q: What are the advantages of slip-on flanges?
Slip-on flanges are easy to align and install, which makes them cost-effective and less labor-intensive than other flange types. They offer a reliable seal and are ideal for systems where precision alignment is less critical.
Q: When should I use or avoid a slip on flange?
Slip on flanges are a good choice for water lines, HVAC systems, and general industrial piping where pressure is moderate and installation needs to be quick and affordable. They are not recommended for high pressure, high temperature, or systems with frequent thermal changes, where a weld neck flange would provide better strength and durability.
Q: What’s the difference between slip-on and blind flanges?
Slip-on flanges connect to pipe and allow flow, while blind flanges cap off the end of a pipe or valve. Slip-ons are for inline connections; blind flanges are for sealing or testing pressure without flow. Slip-ons are welded to pipe, while blind flanges are bolted to the end of a pipe run or equipment.
Q: What are the pros and cons of slip-on vs weld neck flanges?
Slip-on flanges are easier and cheaper to install, suitable for general service. Weld neck flanges offer greater strength and fatigue resistance due to their tapered neck and butt-weld connection, making them better for high-pressure or critical applications.
Q: How do I install a slip-on flange?
To install a slip-on flange, slide it over the pipe – the pipe should be recessed by an amount equal to the pipe’s wall thickness plus a gap, typically 1/8″ to 1/4″, to avoid damaging the flange face during welding and ensure adequate material for the internal fillet weld. Perform a fillet weld on both the inside and outside edges to secure the connection.