A slip-on flange is a type of flange that is designed to slide over the outside of a pipe and then be welded in place. This type of flange is known for being very easy to align and install. This makes it a very cost-effective option for use in low to moderate pressure piping systems. As it comes with a simple design, you can weld inside or outside the flange for a solid seal that is completely leak-resistant. This type of flange is used in a variety of different applications across different industries. They are well-known for being very flexible and for being very simple to fabricate. This guide will help you to know about exactly what sleep-on-flanges are, their dimensions, application usage, and what the different standards are available, so that you can choose the best according to your needs.
What is Slip on Flanges?
A slip on flange is known to have important construction components in the piping systems and is commonly used in the installation procedure. It is made with a small bore, which is a little higher than the outside of the pipe and then the flange is slipped over the pipe smoothly and welded on the outside and inside. This design makes sure that it aligns correctly and that it has a secure connection without making elaborate preparations. According to the standard definition of slip on flange, many are commonly used in instances of low and moderate pressure services because they are relatively cheap and simple to produce. It is one of the flanges that are easy to install, user-friendly, and cost-effective. Comparing the Slip on Flange to the weld neck flange, the former is considered to be used as a general choice when less demanding applications are to be employed, and the cost reduction and also the easy installation remain the major priorities.
How Slip on Flanges Work?
The primary purpose of Slip On (SO) flanges is to ensure that there is a secure, leak-resistant connection between pipes, valves or other fittings in a piping system. Installation would proceed with the flange being slid over the end of the pipe with the inner diameter of the flange was slightly bigger than the outer diameter of the pipe to allow it to fit and be properly aligned. This design enables simple positioning and is beneficial in ensuring a smooth and consistent path of flow.
When properly positioned, the flange is then fillet-welded on the interior and exterior of the pipe. Such a two-way welding technique boosts the joint strength and increases its resistance to operating conditions. Moreover, the flange face gives a solid sealing surface with ease of alignment with a gasket or a ring to achieve a tight sealing and reduce the chances of leakage.
Types of Slip on Flanges
There are different types of slip on flange available based on the sealing surface and application requirements:
Raised Face (RF) Slip on Flange
The most used and common types of Slip on Flanges are Raised Face, which has a small raised sealing surface around the bore. This design helps to maintain and concentrate the pressure on the gasket and provides a better sealing performance in high-pressure systems.
Flat Face (FF) Slip On Flange
This flat face slip on flanges is commonly used in low-pressure applications. If we comp[are the RF and FF slip on flanges, the flat ones is firsy choice when connecting cast iron flanges of flat surfaced equipment.
Ring Type Joint (RTJ) Slip On Flange
The ring-type joint of the Slip on Flanges is a metal ring gasket that is used in high pressure or high-temperature environments where leak-proof and strong joints are required.
Long Weld Neck Slip On Flange
The long weld neck slip on flanges are used to distribute the stress of the structure in different piping systems.
Standards and Grades of Slip on Flanges
- ASTM A105 for carbon steel slip on pipe flanges.
- ASTM A182 for alloy and stainless slip on flanges. (Alloy for F11, F22, stainless for F304/F304L, F316/F316L)
- ASME B16.5 for pipe flanges and flanged fittings.
- BS 3293
- DIN 86029
Slip on Flanges Dimensions and Pressure Ratings
These flanges are manufactured based on various capabilities of the pressure and size, based on the needs of the user, and the information about the slip on flange dimensions and pressure rating is given below in detail.
| Category | Specification Details |
| Common Outer Diameters | 1/2”, 2”, 3”, 4”, 6”, 8”, 10”, 12” up to 24” |
| Custom Outer Diameters | Up to 60 inches |
| Imperial Pressure Class | Class 150, 300, 400, 600, 900, 1500, 2500 (# or LB) |
| Metric Pressure Rating | PN 2.5 to PN 250 |
| Flange Face Types | RF (Raised Face), RTJ (Ring Type Joint) |
Advantages of Using Slip on Flanges
Slip-On (SO) flanges are very popular in piping systems because they are conveniently designed and cost-effective. The main advantages that make them popular in various Industries are listed below:
Easy Installation and Alignment
The slip-on design enables the slipping of the flange over the pipe, and then welding is done, which is easy and efficient in positioning. Before the final welding, minor modifications can be made, and this guarantees alignment.
Cost-Effective Option
SO flanges are simply designed and do not involve complicated manufacturing and the use of materials. They do not usually need much machining and welding preparation as required by other neck flanges and are therefore a low-cost option in applications of lower to moderate pressure.
Reduced Welding Time
They are installed in less time as they are welded with fillet welds, as opposed to butt welds that are fully penetrating. This assists in lowering the cost of labor and welding consumables.
Large Presentation and Material Choice
The Slip on Flanges come in different sizes, pressure classes, and types of alloys, which include carbon steel, stainless steel, and alloy steel. This flexibility allows it to work with other piping systems and conditions.
Space-Saving Design
Slip on flanges also have a small profile and no long neck, meaning that they do not take up as much room to install as weld neck or socket weld flanges. This makes them suitable for systems that have space constraints.
Appropriate to Low-Moderate Pressure Systems
They are suitable for low to extreme pressure or high temperature equipment, so they are ideal in water lines, air systems, and general industrial services.
Simplified Fabrication
The design ensures that on-site installations do not require the use of highly accurate pipe cutting and are easier to make.
Application Usage of Slip on Flanges
In conclusion, a slip on flange is an effective and economically viable way of establishing safe points of connection in low-pressure to moderate pressure piping systems. Slip on pipe flanges are a popular choice in the oil and gas industry, water treatment industry, and the general engineering industry due to their easy installation, alignment, and simple construction. The flanges are versatile and efficient with standardized slip on flange dimensions, wide material selection, and suitability for a variety of pressure classes. They might not be the best choice in extreme pressure services, but a well-selected slip on flange has provided reliable services, less time for installation, and long-term worth. Solitaire Overseas is the major manufacturer and supplier of all kinds of Slip on flanges and other materials. With our strict quality checks, every product is safe and efficient for different industries.
