In industrial piping systems, expansion joints control thermal expansion, vibration and movement. Such joints permit flexibility in the system and are protected against damage by temperature changes or mechanical stress. There are single arch and double arch expansion joints. Picking the right one can affect the performance, longevity and safety of your piping system.

This article will explain the differences between single arch and double arch expansion joints. We discuss their designs, advantages and best use cases.

The single arch expansion joints have a single flexible bulge, or arch, to absorb movement. This kind of joint typically uses flexible rubber materials such as EPDM or Neoprene and is used in systems requiring moderate flexibility. A single arch equips the joint to accept axial, lateral, and angular motions in systems that move somewhat but not excessively.

One arch structure has some advantages:

Most single arch expansion joints are used in moderate vibration and movement environments. Some common applications:

For applications where flexibility is required without extreme demands the single arch joint strikes a good balance between performance and cost. It performs best in situations of compact design, easy installation and moderate movement absorption.

Double arch expansion joints have two flexible bulges, or arches, that provide more flexibility and movement absorption than single arch joints. This extra arch gives these joints greater axial, lateral and angular motion tolerances and is suitable for systems under extreme vibration, pressure or temperature conditions.

Materials used in double arch expansion joints are typically the same as in single arch joints – EPDM, Neoprene, or other flexible rubber materials. The two arch designs have their advantages though:

Double arch expansion joints are used where systems are subject to extreme movement, vibration or pressure changes. The following are some common scenarios where they shine:

The extra flexibility of double arch design makes these joints indispensable for industries dealing with high mechanical stress, vibration and thermal expansion. They are more expensive and require more space for installation but the higher performance and durability often justifies the higher cost in high-demand applications.

A very important consideration when choosing single arch versus double arch expansion joints is their ability to absorb movement and vibration.

Single Arch: Such joints may be used for moderate motion in piping systems where flexibility is required but not essential. They absorb axial and angular movements but not extreme vibrations or high lateral forces.

Double Arch: The double arch structure allows for much more movement and protection in systems with high vibrations, movements, or pressure variations. This additional arch increases joint flexibility and dampens vibrations. That makes double arch joints suitable for environments with high loads in multiple directions or where vibration damping is required.

Double arch expansion joints are more durable in systems with high pressure environments. Its dual-arch design distributes pressure more evenly, reducing joint wear and tear over time. They are therefore suited for demanding applications where longevity and reliability are important.

Conversely single arch joints are still very tough in lower pressure applications. They are less robust in extreme conditions but durable enough for moderate systems, and relatively inexpensive.

When comparing single arch versus double arch expansion joints, consider both the initial investment and long-term performance.

Single Arch: Such joints are generally less expensive initially and are an appropriate choice for systems with tight budgets or less demanding environments. Because of their small size they require less installation space – another advantage of compact systems.

Double Arch: They have a higher initial cost but double arch joints usually pay off in the long haul because they are more resistant to wear and perform better in extreme conditions. However, their greater size also means that they require more room for installation than smaller systems allow.

Single-arch expansion joints are simpler and smaller to install and maintain. The smaller components take up less space and maintenance is simpler.

The double arch joints are more robust, but more difficult to install because of their size and complexity. The increased flexibility and stresses they experience may also require more frequent maintenance in high-stress environments. However, such maintenance is usually worthwhile in applications where durability is required.

Choose a single arch or double arch expansion joint depending on your system requirements. Assess movement, vibration, pressure and cost carefully. What to consider:

In terms of cost, single arch expansion joints are usually cheaper upfront. Ideally they are used in budget – constrained projects or moderate environments where high performance is not required. But double arch expansion joints are worth the investment in high demand applications due to their longer life and greater durability.

Compare your system requirements with budget and performance expectations to determine which expansion joint is best for your project.

Choose single arch or double arch expansion joints based on system demands. Quick recap: to get you started on the subject:

Single Arch Expansion Joints: These are ideal for smaller systems with moderate movement and vibration. Their installation is easy, they are inexpensive, take up less space, and are less expensive. Then they work well in light industrial applications like HVAC or plumbing systems where conditions are not extreme and budget constraints are involved.

Double Arch Expansion Joints: When your system is under pressure, vibrating strongly or moving very much, double-arch joints can handle the stress and strain. They suit power plants, chemical processing plants and heavy industrial systems where performance and long life are required. They have a higher initial cost and require more space but their extreme performance justifies the investment.

Consider your piping system requirements before making a final decision. Assess movement, pressure, temperature, and available space. Single arch expansion joints provide an affordable, compact solution for less demanding applications but double arch joints are ideal for demanding applications requiring durability and flexibility.

Still not sure? Ask an expert or supplier for advice on the right expansion joint for your application. A sound decision will keep your system safe, efficient and economical in the long haul.

Now you know whether single arch or double arch expansion joints are right for your project. Understand their main advantages and applications to determine which is best for your piping system’s efficiency and durability.