How to Install a Slip On Flange: Step-by-Step Guide
How to Install a Slip On Flange: Step-by-Step Guide
Blog Article
Slip on flanges are widely used in piping systems for their easy alignment and low-cost installation. Unlike weld neck flanges, they don’t require precise pipe cuts and are suitable for low-pressure and non-critical applications. In this guide, we’ll walk you through the step-by-step process of installing a slip on flange properly to ensure leak-proof performance and durability.
What is a Slip On Flange?
A Slip On Flange (SO flange) is a ring that is placed over the pipe end, with the flange face extending past the pipe end. It is then fillet welded on both the inside and outside for a strong connection. These flanges are easy to position and align, making them a preferred choice in many industrial piping systems.
Tools and Materials Required
Before starting the installation, ensure you have the following:
Slip On flange of suitable size and material
Pipe (clean and cut)
Measuring tape or scale
Marker
Welding machine (SMAW/GTAW as per requirement)
Grinding tool
Safety gear (gloves, goggles, etc.)
Alignment tools (optional but recommended)
Step-by-Step Installation Process
Step 1: Prepare the Pipe
Clean the pipe surface where the flange will be installed.
Use a grinder to remove any rust, oil, or burrs.
Ensure the pipe is cut square and smooth at the end.
Step 2: Slide the Flange onto the Pipe
Take the slip on flange and slide it over the pipe end.
The pipe end should protrude slightly (about 1/16" to 1/8") beyond the flange face to ensure proper welding.
Step 3: Mark the Welding Position
Use a marker to draw a reference line on the pipe where the back of the flange sits.
This ensures proper positioning during welding.
Step 4: Tack Weld the Flange
Apply 2–4 tack welds evenly spaced around the flange to hold it in place.
This prevents movement during the full welding process.
Step 5: Perform the Fillet Welds
Weld the inside circumference where the pipe meets the flange bore.
Then, weld the outside circumference between the pipe and the rear of the flange hub.
Ensure clean, smooth, and full-penetration welds to avoid leaks.
Step 6: Inspect the Welds
Once welding is complete, visually inspect the joints for cracks, undercutting, or porosity.
For critical applications, consider NDT (Non-Destructive Testing) like dye penetrant or radiographic testing.
Tips for a Successful Installation
Do not skip the inside weld – it is essential for sealing and strength.
Always use matching material electrodes for welding.
Follow ASME B16.5 or relevant flange standards for tolerances and installation practices.
Allow welds to cool naturally – avoid quenching or rapid cooling.
Conclusion
Installing a slip on flange may seem simple, but precision and proper technique are key to ensuring a long-lasting, leak-free joint. By following this step-by-step guide, you can ensure the safe and efficient installation of slip on flanges in any piping system.
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