Brazing - Vertical - Stopping Foreign Material from Running into Joint

[DW85745]

The vertical copper pipes I need to braze have an outside rubber sleeve -- like HVAC pipe insulation e.g. Armaflex). Some sort of slip material (like grease or some other slick product) was used on the pipe to slide the insulation on. My concern is when I start heating up the pipe, this slip material will start to melt and run into my joint. I would prefer to remove as little of the insulation as possible and even then have only so much I can remove that is visible.

Hopefully someone has a simple good idea on how to stop this from happening?

One thought I had was to wrap tape (maybe duck because it is wide) around the pipe above the joint area and leave it unstuck at the top of the tape to create a sort of well. Then if the material runs, it will we caught in that well area.

 

[OLD TIMER]

You have never brazed before. Anything 5' from the joint you are brazing will melt.

 

[Sponsor]

 

[Sylvan]

To braze near a soldered joint use a heat sink or buy a heat tube to spread on the piping to prevent the heating of the area you don't want to burn

Heat sink can be an wet rag

 

[Sylvan]

https://www.amazon.com/Super-Lube-9...MKHHGHK99DQ&psc=1&refRID=GZBKC89K3MKHHGHK99DQ

 

[DW85745]

Thanks for all replies.
Guess I wasn't clear in my post.
My concern is heating the pipe will most likely cause this slip material, especially if it is grease to run.
A heat sink will work to some degree, but my concern is I will get a certain amount of heat past any heat sink
which will cause the material to reach the melt point and run.

Old Timers post recognize this fact with a 5 foot estimate. This is the basis for my post, but my estimate was about 3 feet. And yes I have brazed before.

Sylvan - not familiar with that product but see if I can find some usage specs.