Cleaning a warm pipe

Legend says that if you remove a stem from a warm pipe, the stem won't fit very well anymore. While I've never found this to be true to any degree for myself, I think it depends on how carefully you remove stems to begin with. If you are not sure, hesitant, or afraid of messing up your pipe, maybe letting it cool first is for you. YMMV

I think the general principle when working with any craft or mechanical device applies: Don't force it. If you encounter resistance removing or replacing the stem, just wait. I do avoid removing stems from hot bowls vs those that are just warm.
I can't figure out why removing a warm part would really hurt anything but I've heard the same warning for about as long as I've smoked a pipe.
Pax

I have seen guys at the pipe shop just rip the stems off like apes ripping sticks off of trees. Then they say, "Hey, it won't stay in any more."

"Was the pipe hot when you removed it?"

"Sure, I think."

"There you go. The legend is true. Never remove a stem from a hot pipe."
A myth is reinforced.
I used to just tell people, "don't worry about it, the laws of physics says otherwise." But, then my blood ran cold watching how guys with big huge uncoordinated hands just rip them out. I've stopped telling people that.

I think the conventional wisdom about removing stems from hot or warm pipes rises from believe that doing so risks stretching the tenon lengthwise, thereby decreasing its diameter somewhat and making for a loose tenon-mortise fit. That, at least, is the story handed down to me. The conventional wisdom may be wrong, but I have never felt the need to disassemble a hot or warm pipe. A military mount pipe is a different story, being specifically designed for post or mid-smoke takedown.

I dunno how true it is, just seems that normal physics apply. If something is hot it tends to expand, if you remove an expanded price of lucite or Bakelite, They're both plastics. Plastic expands quite a bit when heated. When removed in its heated state it forces the plastic to shrink, now its shrunken form at a heated state will shrink even more when cooled leaving a loose fit when cool. I hope that wasn't too confusing.

In dealing with the expanding and contracting metals, in fabrication and casting, most materials when they heat up will go back to normal mass/volume when they cool. So, if you heat up a stem, will it not go back to normal when it cools, and if not, what voodoo physics are involved with that?
I like the stretched stem theory, although I would question whether a stem ever gets that hot, and if so, were you pretending to be a freight train?
I've also heard that when the stem is removed the moisture in the briar causes expansion and contraction. But, then again, why does the stem being removed affect this as opposed to just happening when the stem is in there?
Someone also explained that when separated the briar doesn't shrink back to its normal size. And, that makes no sense to me either.
Sure, there is expansion and contraction at different rates. This makes it easier to remove a stem that was put in the freezer and loose stems will tighten up temporarily when smoked from the heat. I get this. But, once they return to normal temperature, they should also both return to same mass/volume.
Nah, I think I like the stretched stem idea better. I have never had an issue with one of my stems, and I will pop them apart while smoking, after a smoke, before a smoke, whenever the notion hits. And, I have never had a loose stem. Maybe, these big heavy handed guys just yank 'em apart, stretching the stems. Maybe. That works better than any of the suggested ideas that I've heard over the years.

Me, ha ha, as said, I remove my stems after each smoke, sometimes during a smoke. But, I am protected by the briar gods and Lady Nicotine blesses my pipes with the inability to have stretchy stems. Ha!! Besides, I am a slow smoker. My pipes never get very hot.

I think you'll find the orthodox practice is not to remove the stem when warm.

I seldom ever remove my stem for cleaning. Only times are perhaps once a quarter for a deep cleaning or in instances where it would seem that the pipe might impart an unwanted flavor.
I do a draw with no tobacco in the pipe to make sure there aren't any off flavors, pack pipe and do another dry draw to make sure still nothing odd. If good to go I light up, if there were off flavors I would clean the pipe; but, since the cleaning would be prior to smoking the pipe would be cool and removing the stem wouldn't be cause for concern.

It may be folk lore, but I abide by the notion that you don't remove the stem from a hot or warm pipe, because it's more fragile. I always get back around to it, so what's the rush? It's part of the slow, deliberate self-discipline of pipe smoking, when every other human activity is done in a frenzy of speed.

Removing a stem while the pipe is still warm is blasphemy. The pipe Gods will forever be furious with you and your pipes will smoke wet and hot for the remainder of your life. Never Never Never touch your pipe until it has cooled for a minimum of 12.35 hours.
I have a ritual where I smoke my pipe, when I am done I put it in round rack I have for 6 pipes and then let it cool over night and then the next day I will clean it. It has worked for me these past 15 years.

I don't know if removing the stem from a pipe when it is warm will alter the tenon dimensions. Nominally, once it cools, it should return to its normal size. However, a warm stem will expand a bit, meaning that the stem will likely be very tight when it is warm. I always understood the danger was that you could break the tenon or crack the shank, either when removing the stem or trying to replace it while it is still warm because of the tight fit. One might also imagine that the tight tenon will, if one repeatedly does this, abrade the mortise (a tiny bit, each time) and enlarge the mortise slightly, resulting in a loose fit in the end. It may not matter, but it is easy enough to wait, so I usually wait until the pipe cools.