banging in drain pipes

[brianb]

While draining hot water and sometimes cold water the drain pipe makes a loud banging ( 3-5 times). I thought it could possiblily been the pipe expanding and hitting something. I've located the pipe in the basement wall and removed a small piece of sheetrock. I did this to spray some expanding foam into the hole in the plate where the pipe passes though. I haven't done this yet. Are there any opinions or concrete solutions to this problem. Thanks for the replies in advance.

[HayZee518]

I don't see how a drain pipe would bang! It's all gravity flow with no pressure. Are you sure it isn't a hot water feed pipe?

[canoebuilder]

any hole where pipe goes through should NOT be tight.
as HayZee said not haveing pressure there could be little creeking noise if hot water is to expand pipe but no banging...you sure it is pipe and not cold water going into a Drained Hot water heater that is still turned on.
This would expand and boil very fast and make some LOUD banging noises.
Gerry

[brianb]

I'm sure it is the drain pipe. If I pour hot water down the sink drain, say from a pot of pasta, the drain pipe bangs 3-5 times. I have measured and I can get to the drain pipe and vent from behind the range. That is where I will cut the next hole in the wall to try to figure out what is makeing the noise. Thanks for the responses. Any new advice will help. Thanks

[HayZee518]

IF the drain pipe made a ninety degree bend somewhere in the wall then went down, even pouring pasta water in it wouldn't make a banging noise unless there was a gas pocket with debris at that bend. maybe there is a trap in the drain line, that would account for the water getting superheated all at once and starts to bang but seems highly unlikely.

[canoebuilder]

If it only does this with HOT water I would say it is an expansion problem.
As HayZee said if the pipes runs in a vertical direction to a horizontal direction this may be the problem.
1st off what material is the drian pipe...cast iron / pvc / abs ???
What size is the drain????
I can see it being PVC in too tight holes going horizontal, and each vertical section being up against a stud....This would cause a bang as the horizontal section tried to expand, and the flex in the vertical sections rapping against the studs......
If this is the problem you would need to get pipe away from studs and or band the pipe tight to the studs to stop it from flexing...
I do not believe it is gas pockets or superheated water.
Gerry