What are slip-on flanges?

Among the wide variety of forged flanges are some sliding types commonly called slip-on flanges. This is a type of flange that is low-cost and easy to install.

Main characteristics of the slip-on flange

Slip-on flanges are known for their low materials cost and easy installation. One of the added advantages of these flanges is that they can also be used as lap-joint flanges if Type B or Type C ends are being handled.

There is a wide range of diameters and low-pressure models to choose from. Unlike welding neck flanges, this flange does not have a neck to rest on the pipe, and therefore double welding is necessary.

How do slip-on flanges work?

Slip-on flanges must be slid into the pipe before welding. In this case it is a double weld, both inside and outside, thus providing the durability they need to avoid leaks. Their pressure resistance is rated at approximately 2/3 of that of a welding neck flange. Slip-on flanges are suitable for low-pressure applications and are easy to install and weld onto different pipes. In addition, welding helps to reduce manufacturing costs.

Slip-on flanges do not require a large longitudinal space in the line to be mounted. In addition, they do not require an exact cut in the pipe, and are less difficult to align.

Comparison between slip-on flanges and welding-neck flanges

Applications of slip-on flanges

They are mainly used for fluids at low pressure or with little risk of leakage. It is very common to find these flanges today in cooling water lines, firefighting water lines, low-pressure compressed air lines, and process lines for substances such as steam, oil, gas, condensates, etc. But always keeping in mind that the material to be distributed is at low pressure and the working conditions are not demanding.

Characteristics of slip-on flanges


  • Low cost
  • Ease of assembly and installation
  • They occupy the minimum longitudinal space for a flange.
  • They come in a wide range of diameters.


  • Not recommended for high pressure applications
  • Not recommended for use with hazardous fluids or gases

Quality, design and confidence at ULMA Forged Solutions At ULMA Forged Solutions we have cutting-edge laboratories with the highest standards of technology, quality and productivity, which help us sustain a wide catalog with a huge number of pieces of different sizes (from 1/2 to 102 inches), different pressure ratings and multiple alloys.

We know that each engineering project has very specific characteristics, so although we have a very wide variety of parts, we also design, engineer and produce custom-made flanges based on the needs of each client.

All ULMA Forged Solutions flanges conform to API (American Petroleum Institute), ASME B16, ASME B16.47 and/or MSS SP-44 standards, meaning that their functionality is assured and replacement is easier in case of failure.