Firstly what you wrote doesn't make grammatical sense, but if we look beyond this, then what is this timing chain fitted to? you don't say.
Timing chains are fitted to anything from simple 4 stroke lawn mower engines and ski lifts to 24 litre diesel train engines. Obviously the removal procedure will differ from machine to machine, and there are just too many variables to list here.
So to give you a quick answer that will be of use to you, go and get a good quality workshop manual and read for yourself.
Removal of the timing chain cover, timing chain, and head are needed
It has a timing belt. Please see related two part video included below that shows you the removal process.
Timing Chain
timing chain timing chain
disintermediation
Although I am not a certified mechanic....hell or even a mechanic , I would say no unless the timing chain is in the way of the gasket replacement, you should be able to on most motors replace header gaskets without the removal of the timing chain. ( timing chains are usually involved with the cam/rod repair and or replacement and such)
The timing chain is behind the timing cover which is behind the water pump. To get at it, you'll need to remove everything in front of the cover and loosen the oil pan a little.
timing chain timing chain
timing chain timing chain
No Belt=It has a Timing Chain.=
It has a timing chain
Timing chain