Leaking sprinkler systems can cause tens of thousands of dollars in damage to ceilings, floors, furnishing and other valuables. Preventing these leaks is not an option for installers, it is a requirement. The metal pipe connections in sprinkler systems can be sealed with PTFE tape, pipe dope or anaerobic sealant; the choice of products is dependent on the application.
Sprinkler systems that are composed of metal pipe have two primary causes for leaks. The leaks in the connections of metal pipe as well as the pin hole leaks in the welds. Pin hole leaks can be prevented or eliminated by heating the pipe and coating with an anaerobic weld sealant.
Preventing leaks in the connections and fittings of the pipe can be done with PTFE tape, pipe dope or anaerobic sealant.
PTFE tape can seal connections, if the pipe is not directional. Tightening of the pipe must be done to the proper torque. If the pipe is over tightened or must be loosened to change the direction of the pipe the seal is no longer In other words if it is at the user discretion when to stop tightening. PTFE tape is not recommended on nicked or damaged threads.
Pipe Dope, a solvent based adhesive, remains a paste. It provides a good seal but does not prevent loosening due to vibration or stress. Pipes that change temperature frequently or are near equipment or other sources of vibration may loosen over time.
Anaerobic sealants cure to form a plastic seal. They cure only when in contact with metal and removed from oxygen. This makes them easy to work with and clean up. Many contain PTFE which eases assembly.
Anaerobic pipe sealants provide an instant seal of up to 1000psi and when cured can exceed the burst rating of the pipe. The cure does not happen instantly so if pipes must be realigned within the system to square off the lines, readjusting will not disrupt the seal. The high viscosity material provides seals on nicked or damaged threads.
Should it ever be necessary to disassemble a sprinkler system sealed with anaerobic sealants normal hand tools will do the job. Anaerobic sealants provide inherent corrosion prevention so there are no rusted connections to deal with.
Traditional Anaerobic sealants should not be used on CPVC (plastic) pipe, however, anaerobic pipe sealants have been developed for use on metal pipe work in systems that may also contain CPVC.