Knowledge at your fingertips
Looking into any maintenance technician's tool box or a plant's supply closet likely turns up some type of pipe thread sealant. But reaching for the nearest pipe joint sealing material can lead to serious problems, including leaks, pipe system damage, contamination, and plant downtime.
As the name suggests, pipe sealants (also known as pipe joint compounds), seal threaded pipe fittings and block the leak path along the threads.
Types of sealants
There are three basic types of pipe sealants in use today: teflon tape, pipe dope, and anaerobic resin compounds. The experience of the technician and availability of the product dictate which one is used. Each type has properties to recommend its use.
The purpose of this white, non-sticking tape is to serve as a lubricant when threaded parts of a piping system are being assembled. The inherent slipperiness of the material makes assembly easier.
Strictly speaking, PTFE tape is not a thread sealant. The tape may have the effect of clogging the thread path, but it does not actually adhere to surfaces as a true sealant should. During installation, the tape must be carefully wrapped in the direction of the threads or it unravels and tears.
Advantages: PTFE tape can be applied quickly with no mess. It supplies sufficient lubrication to enable pipe system components to be easily assembled without damage to threads. The product is easy to carry and store, and has an indefinite shelf life.
Disadvantages: PTFE tape does not adhere to thread flanks, and does not provide a secure seal. Because the tape is thin and fragile, it is prone to tearing when pipes are being assembled and tightened. Bits of torn tape can migrate into a fluid system, clogging valves, screens, and filters. PTFE tape may get dislodged during pipe adjustments, allowing leak paths to form.
Recommended uses: Widely used in plumbing, this material is adequate for assembling standard water pipes and fittings. PTFE tape offers no resistance to vibration and should be avoided in high-pressure systems.
Pipe dope has been used in industrial applications for decades. The material relies on a solvent carrier and hardens when the solvent evaporates. The resulting seal adheres to all plastic and metal pipes and effectively blocks leak paths.
Because it contains solvents, pipe dope has a tendency to shrink over time as the solvent dissipates. This condition creates the potential for the dope to pull away from the thread walls or crack, allowing leaks to develop. Pipe dope is usually applied to threaded components with a brush or spatula.
Advantages: Pipe dopes are inexpensive and relatively easy to use. Their chemical composition is compatible with all pipe materials, including plastic. They harden quickly and produce a moderate to strong seal.
Disadvantages: Solvent-based pipe dopes can loose their effectiveness due to heat aging. When the seal shrinks and cracks, leaks can develop. This possibility is especially true with systems that are subjected to significant vibration. Pipe dopes may lack sufficient resistance to solvents.
Recommended uses: Solvent-based pipe dopes provide an adequate seal in applications where high temperatures and pressures are not expected. Pipe dopes offer minimal resistance against vibration. They are acceptable when the installation of a piping system does not require adjustment of components more than a few minutes after assembly.
Anaerobic adhesives use a different cure chemistry than solvent-based pipe dopes and do not contain solvents. The cure begins when the sealant is confined within the threads of the metal pipe connection and air is excluded.
Without solvent content, the cured material does not shrink or crack, and maintains its sealing properties even after heat aging. Because of their chemistry, anaerobic resin compounds exhibit excellent temperature and solvent resistance.
Advantages: Anaerobic compounds fill the voids between pipe threads, creating a seal. The compounds cure slowly, providing additional time to make adjustments to pipe system components without damaging the seal. Once cured, the compounds form a strong seal that resists the effects of temperature, pressure, solvents, and vibration.
While some sealants produce bonds that make disassembly difficult, joints sealed with anaerobic resins can be taken apart with standard hand tools. Many anaerobic thread sealants contain Teflon or similar lubricants which aid assembly and reduce the potential for damage to pipe system components.
Disadvantages: Because of their chemical composition, compatibility of anaerobic adhesives with plastic pipe and fittings should be verified before use. Although these compounds cure sufficiently for many immediate uses, a 24-hr period should be observed before activating high-pressure systems or allowing significant shock or vibration. Anaerobic adhesives can be difficult to remove from clothing or gloves.
Recommended uses: This class of sealants provides the strongest, longest-lasting seal presently available. They are recommended for temperatures up to 300 F, pressures up to 10,000 psi, and where vibration will be encountered. These sealants are the choice when installers must make minor adjustments to a piping system.
1. Choose the Right Caulk
Caulk that keeps air and water out over time is a necessity when sealing around the home. For a long-lasting seal, choose permanently waterproof, flexible, shrink-crack-proof 100 percent silicone. Avoid using acrylic caulk, which can shrink and crack over time. Air and water can seep through gaps left by cracked caulk. Those leaks can lead to water damage, mold growth, and higher energy bills.
2. Clean the Surface
Remove old caulk, dirt, and loose particles with a caulk-removing tool, or a wire brush for concrete and masonry applications, and wipe clean with a cloth. Apply masking tape to either side of the joint to create a straight edge. (Remove immediately after caulk application.)
3. Prepare the Tube and Seal
Cut the nozzle to desired bead size. Pierce the inner seal with a stiff wire or other similar object. Insert cartridge into caulking gun. Seal around unsightly cracks or spaces inside and outside the home. If using a caulk gun, squeeze with even, consistent pressure to control the rate at which the caulk leaves the tube.
4. Smooth the Caulk Seal
Use your finger or a wet caulk-smoothing tool within two to five minutes of application.
5. Store the Tube and Clean
Squeeze the caulk until it's barely coming out of the tube. Replace the cap, or use a nail in the tube opening. Wipe hands with a dry cloth before washing with soap and water. To clean the area around the caulk, use mineral spirits for silicone caulk, and soap and water for acrylic.
Industries around the world are catching on to the improvements offered by modern structural-grade adhesives. Current structural adhesive bonding techniques have overtaken traditional assembly methods, like rivets and welding, in some of the most critical and sensitive applications because adhesives create a stronger and more durable assembly, offer significant process efficiencies, can bond a variety of dissimilar substrates, and are more aesthetically pleasing. Materials like glass and ceramic can’t be welded and are too brittle for mechanical fastening, but are perfectly compatible with adhesive chemistries.
Three types of adhesives are generally used for structural bonding applications: epoxies, acrylics and urethanes. Adhesive selection depends on what materials are to be bonded, operating environment and process specifications.
Epoxies are excellent for bonding similar materials, especially woods, metals, glass, ceramics, hard rubbers, and some plastics.
Acrylics excel at bonding both similar and dissimilar substrates, though they do have difficulty bonding plastics. Acrylics can even bond oily or dirty materials, eliminating extensive cleaning and surface preparation, though proper cleaning and surface preparation is still recommended for the optimal bonding strength. Acrylics are not as strong or heat resistant as epoxies.
Urethanes are proficient at bonding plastics and dissimilar materials, including metal-to-plastic and metal-to-glass, and can be engineered to provide exceptional durability. Urethane structural bonds are flexible and resilient to vibration, shock, and impact.
A guide to various situations, methods, techniques and materials to prepare surfaces for adhesion.
For high strength structural bonds, paint, oxide films, oils, dust, mold, release agents and all other surface contaminants must be completely removed. However, the amount of surface preparation directly depends on the required bond strength, environmental aging resistance and economic practicalities.
There are three basic methods of removing contaminants: chemical cleaning, abrasion and degreasing.
CHEMICAL CLEANING is popular for preparing metals. It includes treatments which etch the surface to form highly adhering oxides, or deposit complex inorganic coatings. Chemical cleaning, where applicable, provides the best surface for adhesion.
ABRASION METHODS include sandblasting, and use of abrasives and finishing materials. Sandblasting with fine sand can only be used on substrates sufficiently thick to prevent distortion.
DEGREASING may be used when maximum adhesive strength or outdoor weather-resistance is not critical. Surfaces are cleaned with either a hot alkali solution or solvent vapor. To use either method, surfaces must be free of rust, paint and scale.
The Number One cause of catastrophic equipment failure is "Vibration". Mechanical fasteners tend to loosen with vibration. This causes reliability issues & unscheduled downtime.
Anaerobic Threadlocking Adhesives fill gaps between the threads and cure to create a shock-proof, vibration proof assembly. Another issue is "Corrosion". Because of this, it becomes difficult to disassemble the fasteners causing extra downtime & risk of injury to workers.
Threadlockers also seal the gaps between the threads, preventing ingress of moisture and protecting against corrosion and galling.
TECHSOLUTE offers threadlockers in different strengths to facilitate easy disassembly.
Using check-nuts / Nyloc nuts / spring washers / split pins, etc. add to unnecessary inventory expense. Threadlockers not only eliminate these inventory costs - they also offer lower cost-per-application than conventional hardware.