Black Pipe pressure test - lost 0.5 PSI Over night

Hi,

I am planning to install the BP for myhouse myself.

For test, I did a test install using just a couple of joints and some
BPs. I have bought a air test meter and I put 20 PSI in the pipe over
night. Morning I have lost about 0.5 PSI.

Is this normal? due to temp? Or I need to tighten my pipes more..

Also, any advise on extending the wrench handle. I have 12 inch pipe
wrench.. someone told me we can put a pipe as an extension and use it
like 18 inch wrench.. Good idea?

BTW, in the above experiment I am using 1 inch pipe and 3/4 inch
pipe. Used pipe compound also (Hercules compound, made for Gas line
connections)..

Will appreciate any expert insight..
DJ