Fire Protection – Tape – Dope – Pipe sealant comparison.

Laurie Gibbons
Fire Protection, Industry Applications
April 20, 2010

Fire protection sealants prevent leaks in sprinkler systems. 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 depends on the application.

fire protection sealants weld sealant

Sprinkler systems composed of metal pipes have two primary causes for leaks—the leaks in the connections of the metal pipe as well as the pinhole leaks in the welds. Pinhole leaks can be prevented or eliminated by heating the pipe and coating the welds with an anaerobic weld sealant such as Permabond HL126.



Three common ways to prevent leaks in sprinkler systems are PTFE tape, pipe dope, and anaerobic sealants.


PTFE tape can seal connections if the pipe is not directional. Tightening of the pipe must be done to the proper torque. If you need to loosen the pipe to change the direction of it, the seal is no longer. In other words, it is at the user’s discretion when to stop tightening. PTFE tape is not recommended on nicked or damaged threads.

Pipe Dope

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 vibration sources may loosen over time.

Anaerobic Sealant

Anaerobic fire protection 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 you need to realign them 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.

Do not use anaerobic fire protection sealants on CPVC (plastic) pipe. However, anaerobic pipe sealants are available for use on metal pipework in systems that may also contain CPVC.

Let’s Discuss Your Project.

Find out more
Find out more
Find out more

Latest Posts