Lap Joint vs Slip-On Flange, Everything you need to know

Are you struggling to decide between a lap joint flange and a slip-on flange for your piping system? Wondering which type will best meet your specific needs? Understand the key differences between these two flanges to make the right choice. Each serves a unique purpose and comes with distinct characteristics. 

Both of them are ideal for different applications. In this article, we’ll help settle the debate regarding “lap joint flange vs slip on flange.” We’ll look into the definitions, uses, and advantages of both lap joint and slip-on flanges. Ready to make the best choice for your project? Let’s get started.

What is a Slip-On Flange?

A slip-on flange, also known as a hubbed flange, features a low-profile hub. This flange connects to a pipe using one or two fillet welds—one on the outside and, optionally, one on the inside. 

But, it is possible to use only a single weld. The bore size of a slip-on flange is larger than that of the connecting pipe. It allows it to easily slide onto the pipe. This design means there is no full penetration weld. It limits its application due to lower weld integrity.

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Slip-on flanges are generally produced in various sizes. They are preferred for lower-pressure applications (ASME class ≤ 600). The advantages of slip-on flanges include:

• Lower Procurement Costs: They are often more affordable than other flange types.
• Ease of Installation: Less skill is required for welding. They do not require extensive pipe end preparation.
• Versatility: They are available in various sizes and materials. They are adaptable to different piping systems.

However, there are limitations:

• Reduced Mechanical Strength: Slip-on flanges are not as strong as welding neck flanges. They can be unsuitable for high-stress situations.
• Potential for Leaks: Relying on a single weld can result in leaks. Especially in high-stress environments.
• Not Suitable for High Temperatures: They may struggle in high-temperature applications. Where stronger connections are necessary.

What is a Lap Joint Flange?

It is sometimes referred to as backup flanges, loose ring flanges, or van stone flanges. It consist of two parts: a lap joint stub end that is butt welded to the pipe. And then a backing lap joint flange that slides onto the pipe before welding the stub end. 

The unique design of lap joint flanges includes a radius at the intersection of the flange face and bore. Making them compatible only with lap joint stub ends.

Lap joint flanges are highly versatile and are available in various materials. These include stainless steel, carbon steel, and other alloys. They are particularly beneficial in applications where the piping needs frequent disassembly. They provide easy access for maintenance or inspections.

Slip on vs Lap Joint Flange: Applications

Slip-On Flanges

Slip-on flanges are widely used in several industries, including:

• Oil and Gas: Ideal for connecting different sections of pipelines.
• Water Treatment: Frequently found in systems that transport treated water.
• Chemical Processing: Suitable for applications where the pressure is moderate and frequent maintenance is not needed.
• Construction: Commonly used in building applications due to their cost-effectiveness and ease of installation.

Lap Joint Flanges

Lap joint flanges are valuable in situations requiring regular access for maintenance and inspection. Common applications include:

• Chemical Processing: Used in systems where corrosive materials are handled and easy access is crucial.
• Marine Applications: Their corrosion resistance makes them suitable for marine environments.
• HVAC Systems: Commonly employed in heating, ventilation, and air conditioning systems for flexibility and easy access.
• Pulp and Paper Industry: Ideal for systems where maintenance and cleaning are necessary.

Slip on Flange vs Lap Joint Flange: Which is Better?

When deciding, consider the specific requirements of your piping system.

Choose Slip-On Flanges if:

• You need a cost-effective solution for moderate-pressure applications.
• Quick and straightforward installation is a priority.
• You are working in environments where frequent disassembly is not required.

Choose Lap Joint Flanges if:

• Your application requires easy alignment and flexibility during installation.
• Frequent maintenance and adjustments are essential.
• You need a flange that can accommodate a range of materials and wall schedules. Particularly in engineered piping systems.

Conclusion

Understanding the differences between lap joint flanges and slip-on flanges is critical for selecting the right flange for your piping system. Both types offer unique advantages and limitations, making them suitable for different applications. Evaluate your specific needs regarding pressure, installation, and maintenance frequency to determine which flange is the best fit.

If you’re looking for high-quality flanges tailored to your specific needs, consider sourcing from LONGAN Flange. They provide a wide range of flanges designed to deliver optimal performance and reliability across various industries. With a commitment to quality and customer satisfaction, LONGAN Flange is your go-to supplier for all flange-related needs.

References:

https://www.sciencedirect.com/topics/engineering/flange-weldhttps://www.researchgate.net/publication/367254059_Types_of_Flanges