Slip On Flange

Slip On Flange


A flange is a reliable device, which is used to connect various piping components. This system is the second most used joining system following welding. They add flexibility and are easy to maintain. The elements can be easily dismantled for maintenance or repairs. The connection within this module consists of a flange, gasket, and a bolting device. Generally, the bolting material and gasket are specially produced from components similar to the pipe to ensure proper productivity. Stainless steel is the most common range of flanges, however, there are a few others, which are also utilized.

Slip-on flanges are one of the most common and popular components used within the industry. They have a low profile hub or head which is connected to the component utilizing one or two fillet welds. The bore size of their hub is larger in comparison to the connections. The low cost and easy installation of these components makes them a preferred choice amongst a lot of people. They come with a wide range of sizes and choices, which enables them to be utilized for different structures. They are widely used across several low pressure systems and in applications where there are space limitations.


These components are used across applications where the risk of leakage is low. They are commonly found in cooling water lines, firefighting systems, low-pressure compressed air lines, steam, oil, gas lines, etc. However, it is important to keep a note that the material, which is transported, has to be low pressure requiring good working conditions.

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

There are a few important distinguishing factors, which differentiate both these flanges in the piping world. Below are a few points, which validate the same.

  • Structure

A weld neck flange can be easily recognized by the long protruding hub while the latter exhibits a low-profile hub.

  • Connection

The biggest difference between both of these is the welding techniques used in producing them. A butt-weld is utilized to form the weld-neck flange, while a fillet weld is used for the SOF component.

  • Pressure

A welding neck flange can be utilized across several high-pressure systems. It provides support for the different structures in the system. A SO flange would fail in extreme pressures and is widely utilized across low-pressure applications.

  • Strength

A WNF component possesses excellent strength and is heavier in comparison to a SOF component.

  • Cost

SOF flanges cost slightly less in comparison to a standard WNF flange due to their unique make-up.

How do you fit a slip on flange?

The module is basically a ring that is placed onto the pipe. They are generally attached to the one of the ends of a component or multiple ends. The flange is positioned in such a manner that the inserted end is shorter than the flange face or set back due to the component thickness. This allows it to be easily slid onto the pipe. This is followed by applying a fillet weld onto the structure sealing and making it leakproof.

Can you weld a slip on flange to a 90 degree elbow?

These components are the most preferred choice due to their low costs. However, they may incur additional costs due to the subsequent fillet weld required to fit them. There are no restrictions imposed when welding slip-on flanges to any elbows, tees, or any other subsequent fitting.

What is the difference between Class 150 and 300 ?

Steel flanges are classified as per various pressure classes which has been dictated by ASME B16.5 standards. Each flange is designed to withstand different temperatures. As there is a rise in the temperature the, pressure rating of the component starts decreasing.

A class 300 flange can easily handle more pressure than class 150 as they are constructed with more metal and can withstand high pressures. There are also many factors, which affect the different pressure capabilities within the flange. Furthermore, the higher the class better are the temperature and other related tolerances across various stress-induced environments.