Definition - What does Pipe Dope mean?
A Pipe Dope is a chemical sealant and lubricant that is applied to the threads of a threaded joint so as to seal the joint and make it leak proof. When applied to the threads, it fills up the voids between male and female threads and safeguards them from damage. It also makes it easy to open the threads while disassembling the joint.
Petropedia explains Pipe Dope
When connecting a threaded joint, it is necessary to make the joint airtight and leak proof. Pipe dope is the lubricant and chemical sealant that is used to make the threaded joint airtight and leak proof. When the pipe dope is applied to the threads before tightening the joint, it ensures that an interference fit is achieved during assembly by making the joint pressure tight and leak proof on tightening. It also lubricates the mating threads and safeguards them against seizing which can cause issues during the opening up or disassembling of the joint.