What causes PVC pipe to swell?

Author: Sean Flatley  |  Last update: Saturday, November 29, 2025

So what can cause pipe and fittings, in an irrigation or pool system, to swell up? You might have guessed it by now – heat! The maximum operating pressure tables for PVC pipe is based upon a temperature of 73° F.

What causes a bulge in a water service pipe?

Bulging water pipes occur when there is an unusually large amount of pressure building up in the pipe. There likely is – or was – a blockage. The water then built up in one spot. With nowhere to go, it pushed on the pipe.

Does PVC expand in summer?

Heat Expansion of uPVC Windows & Doors

When the temperature rises, uPVC undergoes thermal expansion, meaning it expands in size. While the plastic will return to its original form when it cools down, this expansion can be problematic, especially during warm summer nights when securing properties is essential.

Can PVC pipes swell?

Certain chemicals can cause irreversible changes to PVC, including swelling, reduction in tensile strength, and dissolution. PVC's chemical compatibility can be affected by plasticizers and requires careful evaluation, especially with strong oxidizers or at high concentrations and temperatures.

How do you clear PVC pipe blockage?

Apply any household spray cleaner on the PVC pipe and allow it to soak. Next, use a soft-bristled brush to gently scrub away dirt particles from hard-to-reach areas inside the PVC pipe. Wipe down the PVC pipe with a lint-free cloth. Repeat the process as necessary.

FlexPVC - How to reform swollen or ballooned flexible pvc pipe.

What can you use to unclog PVC pipes?

Utilizing chemical-free drain cleaners is a highly effective, eco-friendly method for preserving and cleaning pvc pipe. Natural mixtures, such as baking soda and vinegar, create a foaming action that disintegrates clogs, while enzyme-based cleaners use beneficial bacteria to dissolve organic matter within the pipes.

How do you make PVC clear again?

To restore any type of clear plastic to newer-looking conditions, perform the following steps.
  1. Step 1: Examine the Scratches. ...
  2. Step 2: Get the Area Clean. ...
  3. Step 3: Buff Using a Mild Abrasive. ...
  4. Step 4: Wet Sand for Deeper Scratches. ...
  5. Step 5: Go For a Finer Grit. ...
  6. Step 6: Polish to Renew Shine.

What is the average lifespan of PVC pipe?

Because PVC is immune to corrosion, a minimum service life of at least 100 years can be expected. This figure is supported by a number of independent studies, as well as the experience of many long-term users of PVC piping systems.

Can PVC expand over time?

The higher LCoE means that plastic pipe, such as PVC and ABS, will expand and contract more with a change in temperature than metal pipe. As a result, plastic pipe must be clipped/supported differently to metal pipe. Even small changes in temperature will result in the pipe wanting to expand or contract.

How do you know if PVC pipe is bad?

Signs that your PVC pipe may be bad include cracks, leaks, discoloration, or a foul odor coming from the pipe.

At what temperature does PVC expand?

Expansion joints are usually used where the straight run length is greater than 25 feet and expected temperature change is greater than 60°F. Rigid PVC conduit has a coefficient of expansion of 3.38 x 10-5 in./in./°F. A 10 foot length will change in length about 3/8" with a change in temperature of 100°F.

What does the sun do to PVC?

Color change: Over time, UV exposure can cause plastic pipe to discolor, typically turning yellow or brown in PVC and a faded or bleached effect may occur in ABS. Surface cracking: The UV radiation can cause the surface of the plastic pipe to become brittle and crack.

Does PVC swell in heat?

According to engineeringtoolbox.com, at 40ºC your UPVC can expand by up to 2.4cm, which is likely to affect normal use. In really high temperatures you may notice that your windows or doors become stiff, and they may not open and close properly. This is likely to be because the UPVC has swollen. DO NOT WORRY!

What are the signs of a burst water pipe?

How To Tell If a Pipe Burst?
  • Water Pressure Fluctuations. One of the earliest signs of a burst pipe is water pressure fluctuations. ...
  • Unusual Sounds in the Pipes. Strange sounds emanating from your plumbing system can indicate a burst pipe. ...
  • Wet Spots or Water Stains. ...
  • Unpleasant Odors. ...
  • Sudden Increase in Water Bills.

Why is water coming out of my expansion pipe?

If your overflow pipe is gushing water, it could indicate a serious issue such as a faulty pressure relief valve, a malfunctioning float valve, or a damaged tank. This requires immediate attention from a professional to prevent damage to your property.

What is the process of pipe bulging?

Explanation for Bulge-Forming Process. The basic principle in Bulgeforming is to insert a tubing into a mold, then introducing fluid under extremely high pressure to compress the tube ends towards the center of the mold while forcing the tubing wall to expand into the mold cavity all in one motion.

How much does PVC expand with heat?

The impact of temperature fluctuation can be a major factor in hot water lines, where an 80-foot run of 2-inch-diameter PVC Schedule 80 pipe installed at 73 F can expand up to 1.35 inches when in operating service at 120 F.

Can PVC pipe swell?

It is going to take a little time for that PVC material to cool and become rigid again. In the meantime, while it's still pliable from being heated up, it may swell or balloon out of shape, even though the system pressure is well below the pipe maximum operating pressure at 73°F.

Can you leave PVC trim unpainted?

The truth is that not all PVC needs to be painted. Extruded Cellular PVC, for instance, is created in a way that the pores of the cellular PVC are not showing externally. This product can be left unpainted and there will be no effect to the product.

When should PVC pipes be replaced?

Copper pipes can last up to 70 years, while PVC (polyvinyl chloride) pipes have a lifespan of around 50-70 years. If pipes at your homes are approaching or have exceeded their expected lifespan, it may be the right time to consider a replacement. Water pressure is an essential aspect of your plumbing system's comfort.

What is the difference between PVC and CPVC?

The base material for both is PVC (polyvinyl chloride), but CPVC is taken through a chlorination process that makes it more rigid and also more tolerant of higher temperatures. The added chlorine in CPVC (chlorinated polyvinyl chloride) results in a more flexible material with better insulating properties.

What are the disadvantages of PVC pipe?

PVC pipe is susceptible to damage from real-world shipping and handling conditions. A scratch deeper than the thickness of a dime can compromise an entire length of PVC pipe. Tapping PVC pipe is difficult and time-consuming and can be dangerous - resulting in cracked pipes, injured workers, and severe water loss.

Does vinegar damage PVC?

While harmless for most metal and PVC pipes, prolonged exposure to the acidic nature of vinegar might corrode certain metals, like copper. PVC pipes, on the other hand, can withstand these substances without damage.

Does clear Gorilla Glue work on PVC?

Simply put, The surface of PVC is so smooth that Gorilla Glue doesn't have anything to grip or bind to.

Can you use Vaseline on PVC?

If necessary, additional grease can be added to the joint before tightening it completely. Other products that might seem like they could work are olive oil, Vaseline, and WD-40. Do not use these under any circumstances. They are very thin and won't stay in place.

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