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HOW TO SOLVENT WELD CPVC IN HOT WEATHER

By: Jorge Solorio on March 8th, 2019

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HOW TO SOLVENT WELD CPVC IN HOT WEATHER

Piping Systems  |  Installation Guide

There are a few available methods for joining CPVC pipes and fittings, but solvent welding is often recommended as the optimal solution because of the strong, reliable bond it forms between adjoining pieces of material.

Solvent cement isn’t glue­—rather, it’s a chemical compound that untangles the surface molecules of CPVC material, freeing them to bond with those of another CPVC piece. The result is a fully fused joint that maintains the chemical resistance, temperature and pressure bearing capabilities of the original material.

To reach optimal joint strength, the solvent cement must adequately soften the surface material, and enough time must be allowed for setting and curing. Curing is when the solvent flashes off or evaporates, allowing the newly formed joint to dry and harden.

In cold weather applications, solvent cement and CPVC molecules slow down, requiring more solvent to soften the material and more time to cure or harden the joint. Conversely, in hot environments, the molecules speed up, creating different potential challenges for installers.

By following a few simple guidelines, reliable CPVC joints can be solvent welded at temperatures exceeding 95°F (35°C).

 

Guidelines for Hot Weather Installation

When applying solvent cement to hot pipes and fittings in high temperature environments, our partner manufacturer Weld-On recommends the following tips:

  • Direct sunlight can increase the surface temperature of the material by 20° – 30°F (10° – 16°C), so keep the piping, fitting and solvent cement in the shade as much as possible.
  • If possible, try to create bonds during the cooler parts of the day (morning or evening).
  • Cool down joints with a wet rag before applying solvent cement. However, make sure the joint surfaces are dry at the time the solvent is applied.
  • Shake and mix the solvent cement well before applying to ensure a consistent mixture.
  • Solvents attack hot surfaces faster and deeper than they do average or cold surfaces. So be extra careful to avoid puddling inside the joints.
  • Because solvent evaporates more quickly in high temperatures, make sure the joint surfaces are still wet with solvent when connected. Otherwise, the solvent will not properly untangle the CPVC surface molecules.

 

Warm Weather Solvent Cement Set Times

After the solvent cement has been applied and the pipe is pushed into the fitting, proper time must be given for setting. During the set time, the pipe should not be moved. Recommended set times shorten as the temperature increases.

Following is a table that breaks down how long Corzan® CPVC material scientists recommend allowing a joint to set based on temperature and pipe size:

 

Corzan CPVC Solvent Cement Set Times

 

Warm Weather Solvent Cement Cure Times

Once set, the pipe and fittings can be moved, but the joint must fully cure before the system can be fully pressurized. Similar to set times, cure times are shorter in warmer environments. Also, lower pressure systems require less cure time.

The following table details cure times by temperature and pipe size.

 

Corzan CPVC Solvent Cement Cure Times Per Ambient Temperature and Pipe Size

 

Hot Humid Environments

Often related to heat is humidity, and humidity also has a direct effect on solvent cement cure times. The more humid an environment, the less available space is in the air for the solvent to evaporate.

The general rule here is that pipes in environments that are humid or damp should cure for an extra 50% of the given time. So, if the table above recommends 15 minutes, the pipe should cure for a minimum of 22.5 minutes.

For any questions about specific set and cure times for an application and environment, the Corzan CPVC team recommends directing those to the solvent cement manufacturer.

 

Learn More About CPVC Solvent Cement

For more information on using cement solvent to weld CPVC pipes, check out the Complete Guide to Solvent Cement 

If you have any questions about solvent cement or the appropriate solution for your application, our team of product and engineering specialists is ready to talk.

 

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