How Pipe Supports Can Help Mitigate Piping Thermal Expansion and Contraction

In both residential and commercial buildings, heating and cooling cycles can take a toll on piping systems. When pipes expand due to heat and contract when they cool, they stress joints, supports, and the pipes themselves. Over time, this ongoing stress can lead to leaks, structural damage, and, ultimately, system failures.

Imagine a school building with a long run of hot water pipes. Each time hot water flows through these pipes, they expand. Over time, without proper measures, this expansion could lead to bowing or even bursting pipes, causing water damage and significant repair costs.

What is Piping Thermal Expansion, and What Causes It?

Thermal pipe expansion refers to the natural increase in the length or diameter of pipes when exposed to heat. This expansion occurs because the molecular structure of the pipe material changes as temperature rises, causing molecules to move more vigorously. Common causes of thermal expansion include the heat from fluids inside the pipes or changes in environmental temperature.

The rate and degree of thermal expansion typically depend on three main factors: the pipe material, pipe length, and the temperature differential the pipe experiences. :

●      Material type: Different materials expand at different rates due to their differing molecular structures. Metals generally expand less than plastics.

●      Temperature change: The greater the temperature difference, the more the material will expand.

●      Pipe length: Longer pipes will experience more expansion than shorter ones under the same conditions.

Common signs of stress in piping systems include visible leaks, often resulting from wear at joints, deformation (where pipes bow or stretch beyond their limits) particularly in longer runs, and noisy pipes. Sounds like clicking or rattling, especially when pipes expand against wood or other materials, indicate potential issues with their supports.

How to Mitigate Piping Thermal Expansion and Contraction

The expansion and contraction of the pipe can usually be accommodated by either using existing bends or expansion loops, designing the piping system using expansion joints, or incorporating adequate pipe supports.

Below, we briefly cover expansion loops and joints, but our primary focus for the remainder of this article is how certain pipe supports can mitigate thermal expansion and contraction.

Bends and expansion loops: Incorporating expansion loops, offsets, and bends (elbow fittings) into a plumbing system enhances its flexibility and ensures it can handle movements without stress on connections. Available in various angles like 45-degree and 90-degree, bends redirect flow without affecting pressure. Expansion loops absorb thermal expansion or contraction, preventing undue stress and potential damage. These elements are vital for a system’s long-term reliability, reducing mechanical failures and maintenance needs, and extending the system's lifespan.

Expansion joints: Expansion joints are essential for managing thermal expansion and contraction in piping systems, ensuring their longevity and reliability. They must be carefully selected, installed, and maintained, especially in tight spaces. These joints absorb thermal movement, maintaining structural integrity, and must be placed strategically, correctly anchored, and supported to prevent stress on the system. Proper installation avoids twisting or bending, and regular inspections are crucial to address wear or damage, ensuring optimal performance.

Pipe Supports

Pipe supports are essential for accommodating the natural movement of pipes. Incorrect supports can loosen over time, causing rattling noises and structural stress.

Proper pipe support placement is critical in managing the effects of thermal expansion. Pipe supports like hangers, brackets, and clamps are designed to allow some movement, which helps absorb the stress caused by these cycles. 

Types of Pipe Support

The appropriate pipe support for a given piping system depends on the pipe material.

●      Water supply pipe is Copper Tube Size, commonly referred to as CTS.

●      Gas and drain pipes are considered Iron Pipe Size, or IPS.

To summarize, a one-inch piece of copper or CPVC pipe will require a different hanger type and size than a comparable piece of gas pipe because of factors like wall thickness, diameter, and load (the weight of the piping).

Oatey offers a variety of plumbing pipe support options that allow for faster cooling and pipe expansion and contraction.

Full clamps with nails allow the tubing to expand and contract and are designed for securing copper, PEX, and CPVC CTS piping to mounting surfaces. Made of corrosion-resistant polypropylene, these pipe support clamps feature a pre-loaded, rust-resistant nail for easy installation and a ribbed design for noise reduction. The full clamp offers 360° pipe protection and reduces water line noise.  

Half clamps are ideal for securing tubes to mounting surfaces.

Suspension clamps eliminate contact between the pipe and the framing surface, reducing water line noise. Their ribbed design allows for faster cooling and pipe expansion and contraction. 

Insulating clamps work well to prevent corrosion and accommodate thermal expansion. Constructed of durable, corrosion-resistant polypropylene, these pipe clamps feature a ribbed design that allows the pipe to cool faster and expand or contract freely. These clamps also isolate the pipe from the stud, helping to reduce noise. 

Why does insulation matter? Insulation helps maintain the fluid's temperature within the pipes and minimizes the impact of thermal expansion and contraction by acting as a buffer between the pipe and its surroundings.

CTS Bell Hangers are also designed for light-duty support of copper, CPVC, and PEX piping and provide a 13/16 in. stand-off from the mounting surface. Made of durable, corrosion-resistant copper-plated steel, they allow for the expansion and contraction of multiple pipes. 

CTS J-Hooks are available in various sizes and enable the expansion and contraction of multiple pipes. They provide a fast, economical way to hang copper, CPVC, and PEX pipes from joists and rafters. Made of high-impact ABS plastic, these J-hooks allow nails to sit flush against a wall or stud.

Best Practices for Pipe Support Installation

To ensure the satisfactory operation of a piping system, carefully consider support location and type. Plumbing codes require all piping and its contents to be supported so that the pipe maintains alignment and doesn’t sag.

Proper Sizing

Ensure that the pipe supports are correctly sized for the type of pipe material and diameter. Incorrectly sized supports can lead to excessive stress and noise. Oversized hangers, for example, can lead to pipe movement and additional noise.

Proper Spacing

Follow local code requirements for the spacing of pipe supports to provide adequate support without restricting necessary movement.

Always attach hangers and anchors to walls in accordance with local plumbing codes. For pipe sizes four inches and larger, provide sway bracing at directional changes of more than 45 degrees.

Support spacing should follow applicable plumbing and building codes. Below, we share the maximum horizontal and vertical spacing for Schedule 40 PVC, Schedule 40 ABS, CPVC, copper, and PEX, based on the IAPMO Uniform Plumbing Code and the International Plumbing Code.

However, the information below provides general guidelines and serves only as a reference. Engineering specifications for a particular project may require specific installation instructions.

●      CPVC: Most plumbing and building codes require support for horizontal CPVC pipelines one inch and smaller every three feet; and for diameters 1-¼ inches and greater every four feet.

The UPC states that vertical spacing for CPVC piping should provide a mid-story guide and for expansion every 30 feet. See: Section 313.0 Hangers & Supports, Table 313.3.

The IPC designates the maximum vertical spacing of CPVC as 10 feet. For sizes two inches and smaller, a guide should be installed midway between the required vertical supports. Such guides will prevent pipe movement in a direction perpendicular to the pipe's axis. See Section 308 Piping Support, Table 308.5.

●      Copper: Most plumbing and building codes require support for horizontal copper pipelines 1-¼ inch and smaller every 6 feet. The IPC indicates supports to be placed every 10 feet for diameters 1-½ inches and greater; the UPC, every 10 feet for diameters 2 inches and greater.

The UPC and IPC both call for vertical spacing not to exceed 10 feet. See: Section 313.0 Hangers & Supports, Table 313.3 (UPC); and Section 308 Piping Support, Table 308.5 (IPC).

●      PEX: The IPC requires support for horizontal PEX pipelines 1-¼ inch and smaller every 2.67 feet, or 32 inches. The UPC requires the same spacing support for pipelines 1 inch and smaller; and every four feet for 1-1/4 inch and larger diameters.

The IPC states that the maximum vertical spacing for PEX is 10 feet. For sizes two inches and smaller, a guide should be installed midway between the required vertical supports. Once again, such guides will prevent pipe movement in a direction perpendicular to the pipe's axis. See Section 308 Piping Support, Table 308.5.

The UPC states that vertical spacing for PEX piping should provide a mid-story guide and for expansion every 30 feet. See: Section 313.0 Hangers & Supports, Table 313.3.

Properly sized and placed pipe supports are your first line of defense against the damaging effects of thermal expansion and contraction. They are not just about preventing leaks—they are about maintaining the overall integrity of your system.

Calculating the rate of thermal expansion for your specific piping material is crucial. This allows you to design a system that accommodates movement without compromising stability.

Mitigating the effects of thermal expansion and contraction in your piping systems is not just about compliance—it's about ensuring the longevity of your infrastructure. Proper pipe supports, insulation, and expansion joints can make all the difference.

Sean Comerford is Manager, Inside Sales & Tech Support at Oatey Co. He is a third-generation tradesman with nearly 20 years of plumbing experience, including serving as the lead plumber for commercial/residential new-construction, service and fire protection jobs. He holds a State of Ohio Fire Protection License for Sprinkler and Standpipe.