There are three basic types of thread sealants for metal pipe; pipe dope, PTFE (ex. Teflon®) tape, and anaerobic sealants. Anaerobic sealants are often chosen due to the limitations of dope and tape. Pipe dope is inexpensive and easy to use; however, it is solvent-based, which means it shrinks, hardens, and can crack over time. Vibration in the pipes can hasten the leaks. PTFE tape, often called Teflon tape, is easy to store and use. It is called tape, but it is not sticky. The PTFE lubricates to ease assembly. Tape fills the space between the threads but doesn’t adhere. Any readjustment can cause the tape to shred, creating leaks or allowing pieces of tape to enter the fluid, causing blocked valves, filters, and screens.
Anaerobic thread sealants are 100% solids, so they do not shrink or crack like pipe dope. They cure to form a solid seal that resists vibration loosening. They can contain PTFE to lubricate and ease assembly.
The following table provides a description of several grades of Permabond thread sealants.
|LM012||Hydraulics Sealing Grade,
MIL-S-22473E Grade HVV ASTM D5363
|Americas & Asia|
|LH050||General Purpose, UL Classified||Americas & Asia|
|LH050 PURE||NSF/ANSI 61 Certified, Potable Water Grade||Americas & Asia|
|LH056||Fire Protection Grade||Americas & Asia|
|LH150||Stainless Steel Grade, UL Classified||Americas & Asia|
|MH052||Medium Strength, BAM Approved for Oxygen||Worldwide|
|A1044||High Strength||Europe, Middle East, Australia|
|A131||Low Strength||Europe, Middle East, Australia|
|A129||Medium Strength||Europe, Middle East, Australia|
Anaerobic pipe sealants are only for use on metal pipe. Do not use on plastic.