You should ask him to let you see the WPS that you are welding to. Probably doesn't have one. If he produces one you should follow it. It most likely will include a 6010 root and optional hot and a 7018DC hot, fill and cap.
If the inspector or engineer inquires and you are not following the WPS then you might be cutting the welds out.
The contract specifications WILL address the pressure pipe welding. It will say that you shall follow the WPS (welding procedure specification). Your company should have submitted this information to the engineer or architect for approval before welding.
I suggest that you politely ask to see the WPS, that you want to follow it to keep your company(and him) out of trouble. If he doesn't have one then suggest that they should get one before they get "busted". Until you see the WPS and verify the correct electrodes tell him that a 6010 root 7018 fill-cap is industry standard. Sounds like you are working to ASME B31.1? I do not have that with me tonight.
Your last sentence is your best arguement (7018AC takes longer) Tell him that you can weld it better and faster with the right rods.
Once again, it is all in the WPS. Does he have one?
Take it easy, LongArc, life is short and it doesn't pay off to get upset because of small details.
As a matter of fact, neither AWS nor API and ASME precludes the use of low hydrogen electrodes for the first (or root) pass, son you can't use a written stuff from those institutions to convince your boss.
It's decades of experience that recommends not to use a low hydrogen electrode for the first pass, due to its low penetration properties.
Decades of experience recommend to use a cellulosic electrode (good penetration) such as 6010 or 6011, and then complete the weld with a low hydrogen one.
I used to see that recommendation on literature (catalogues, for example) published by Lincoln and ESAB.
Giovanni S. Crisi