The persistant shock and vibration can cause damage not only to joints but to the plumbing lines themselves especially if already weak due to mineral or chemical erosion.
The likely hood of the pipe leaking would be determined by how bad the hammering is, the age of the pipes, How they were hung and the quality of the solder joints as well as what Bob & RodMan stated.
It is not normally that hard to fix once you find where the pipe is hitting. It can be done with something as simple as a little piece of rubber or a few new hangers.
You can also install a system wide hammer arrestor.
Thanks folks! The hammer is an interior a wall where the fairly new plastic piping is and would be messy to locate. I'm thinking that the water hammer arrestor may be the best option.
In your case yes it may be the best way to go using the water hammer arrestor. But if after the fix if its still bangs, then you need to find this spot and fix it. The vibration and the moving of the PEX tubing in the wall can wear out the plastic in a few years causing a bigger leak.,
If your not sure exactly were the pipe is placed in the wall. Contact a Thermal Imaging company. With a thermal camera they can find the water lines in the wall quite quickly preventing the need to open up larger parts of the walls just to locate the pipe.
I've got research to do.
Found out that when the new addition was constructed the plumber put the lines to the shower valve in backwards. cold=hot and vice versa. To mask his mistake he took the cartridge apart and performed some mumbo-jumbo to make it work properly. Of course this damaged the cartridge which eventually self-destructed. The folks at Zurn were very nice and sent me a new cartridge. Hot/cold are now reversed however no water hammer. Live and learn.
Opps....is there a way you can "remind" this dufous of his mistake?
A client of ours has a case of water hammer at just one shower within their home. Plumber installed an arrestor and solved the problem! Here is recent post about it http://www.nesthomeimprovement.com/blog/water-hammer/