what is a transition fitting?

[Another-Plumber]

transition fitting is a pe to steel riser

i dont think that fits here, 1st of all, think about it, the gas company tagged it... NOT an inspector, a simple man did

 

[IFIXH20]

1st of all putting a UNION after the shut off is plain stupid, show me a picture of a "flared gas shut off-union-gas flex".... CANT BE DONE, unless your some kind of hack

Some state/cities Still require a union with a flex gas line, thats right. As far as your other statement I don't know what you are talking about.(flared -shutoff - union -flex). What the hell is a hack - The only hack i know is on the golf course.
BTW is your drip leg behind the water heater?

 

[KULTULZ]

maybe he/she is talking about a transistion fitting for your gas line, An transition fittings for hard pipe to flex line

wouldnt it be ok going from black steel pipe to a brass shutoff then flex?

I think (and I am no professional) that the poster is correct. Black pipe to brass transition fitting to flex coup[ling. At least that is how mine is plumbed (supposedly by a professional).

I would post a photo but I left the camera at my other residence...