When completing a plumbing project, determining the right thread sealant to use depends on a number of factors. Knowing what options are available, when to use them and how to apply them will help you achieve and maintain a watertight and airtight seal between pipes every time.
Introduction to Pipe Thread Sealants
Pipe thread sealants are a crucial component in ensuring the integrity and safety of piping systems. These sealants are designed to create a secure and leak-proof connection between pipes and fittings, preventing the escape of fluids or gases. When selecting a pipe thread sealant, it’s essential to consider factors such as temperature, pressure, and the type of fluid being transported. A suitable sealant should be able to withstand the operating conditions and provide a consistent seal over time. It’s also important to note that some sealants may require permission to access certain areas or may be subject to access denied errors if not used correctly.
Almost all plumbing systems (such as a natural gas pipe, compressed air pipe or a shower head and beyond) will have a section where a threaded connection is required. Threaded pipe and fittings are considered male and female and most commonly contain NPT (National Pipe Tapered) threads. NPT means that the male and female threads are tapered when cut, allowing for easy alignment of the male threads at the start of the joint assembly. As the joints are tightened, the harder it becomes to turn. These joint assemblies cannot achieve a watertight/airtight seal on their own, so when assembling, an approved thread sealant is required to fill the remaining voids in the root of the threads to create a seal.
How to Choose a Thread Sealant
What type of sealant should you choose? Thread sealants are available in either a tape or a pipe joint compound (often referred to as “pipe dope”). Each has benefits and features but knowing which one to choose and how to apply it to your pipe's surface will save you time and frustration.
- Thread Sealant Tape, such as Hercules® MegaTape, comes in a variety of colors, widths, thickness and densities.
- Colors are used as visual identifiers to show a person what is flowing through a piping system. For Instance, yellow thread sealant tape is required by most municipalities when assembling a gas piping system. General purpose tapes are usually white and are also available in grey, which make it more aesthetically pleasing when used on pipe materials that are similar in color.
- Widths include ½”, ¾”, and 1”. A ½” width tape would be ideal for smaller diameter pipe. When assembling larger diameter pipes a ¾” or 1” width would be best because it provides better coverage on the threaded section of the pipe.
- Thickness is usually referred to by mil. Higher mil thickness reduces the number of full wraps necessary to create a water/airtight seal.
- Density refers to the pipe's ability to be compacted into the root of the threads. Tapes higher in density prevent excess stretching during assembly, which would lead to less compaction and possible leak paths.
- Pipe Joint Compound, such as Hercules® Megaloc® and Hercules® Pro Dope®, should be selected based on pipe and fitting material compatibility, chemical compatibility and temperature performance ranges. To determine pipe joint compound compatibility and temperature performance ranges, please refer to the submittal sheets located at www.oatey.com.
Material Compatibility is important to know when assembling a threaded joint. For instance, if a joint compound is used on a non-compatible material it can cause the material to degrade rapidly and lead to a possible failure.- Chemical Compatibility is another factor to consider when determining what pipe joint compound to use. The chemical composition of the pipe joint compound can be compromised if prolonged exposure to an incompatible chemical is introduced.
- Temperature performance range is the temperatures at which the pipe joint compound will function. Brushability temperatures and performance ranges must be determined prior to selecting a pipe joint compound especially if being utilized in systems with temperature extremes.
Preparing the Threaded Connection
Before applying a pipe thread sealant, it’s crucial to prepare the threaded connection properly. This involves cleaning the threads to remove any dirt, debris, or old sealant residue. A filter or cloth can be used to wipe down the threads, ensuring they are dry and free of contaminants. For copper pipes, a specialized cleaning solution may be required to remove oxidation and ensure a secure seal. It’s also a good idea to test the threads for any damage or wear, and to use a guide to ensure the sealant is applied correctly. The price of a pipe thread sealant can vary depending on the type and quality, but it’s essential to find a product that meets your specific needs and provides reliable results.
How to Apply Thread Sealant
Whether you are applying a thread sealant tape or a pipe joint compound, you will always apply them to the male threads. Applying only to the male threads will reduce the possibility of blocking or restricting the inside of the pipe and fitting. - Tape and joint compound can be used in conjunction with one another. Once the male threads are correctly wrapped with thread tape, you can apply a coating of pipe joint compound over the thread sealant tape before assembling the joint. Due to pipe and fittings NPT tapered design, thread tape is designed to go directly on the male threads to ensure that as the joint is assembled, the tape will be compacted into the root of the thread. A thread tape’s elasticity allows it to stretch when applied and does not completely fill the root to crest of the thread. Applying joint compound on top of the tape will fill any remaining voids as the joint is assembled, and any excess joint compound will be pushed out of the fitting.
- Once you have selected the correct tape sealant for your application, you will wrap the tape 3-5 revolutions in a clockwise motion keeping the tape just above the last male thread of the pipe or fitting. Wrapping the pipe in the same direction that you would screw it into the fitting will prevent the tape from unraveling during assembly.
- When applying pipe joint compound remember that you are filling the thread openings, so applying the compound in the same direction as the threads will sometimes lead to poorly filled joints. Brushing across the threads will provide better coverage and will ensure that you will always fill the threads.
Troubleshooting
If you’re experiencing issues with your pipe thread sealant, there are several troubleshooting steps you can take. First, check the sealant for any signs of wet or dry rot, which can indicate a failed seal. Also, inspect the threads for any damage or debris that may be preventing a secure connection. If you’re still having trouble, try accessing the manufacturer’s website, such as Home Depot, for guidance and support. When troubleshooting, it’s essential to keep track of your progress and note any findings, as this can help you identify the root cause of the issue and find a suitable solution. By following these steps and using the right products, you can ensure a secure and leak-proof connection in your piping system, even in low-temperature or high-pressure conditions, and avoid common issues like tracks of dirt or debris that can compromise the seal.