Banging pipes - types of banging

I have tapping noise from the heat system in my apt building. I know what causes it. The pipes are expanding from heat.
For many years I heard a fast series of clicks every 30-60 minutes or so, but lately, I've been hearing a "slow tapping," which is one CLICK and then five seconds of silence and then another CLICK. This lasts 1-2 minutes.
Do you know why this "slow tapping" would happen as opposed to the old tapping?
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On Sun, 2 Dec 2007 16:07:07 -0800 (PST), Richard Fangnail

Somebody loves you. Are these two taps? -- Oren
"The voices in my head may not be real, but they have some good ideas!"
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Same cause.

Pipe hangers are older, and now have enough corrosion on them to create enough friction that the pipe doesn't slide more-or-less smoothly through them like it used to. Now, it moves in a series of jerks.
Try putting a little bit of grease at every point where a pipe is in contact with a pipe hanger.
--
Regards,
Doug Miller (alphageek at milmac dot com)
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