They're used heavily in the aviation fuel industry but that's the only place I've personally come across them. I would ask Franklin or their local rep for their input for your particular service.

They fill a nice niche if you want/need a complete double block & bleed assembly in one unit, however be aware that they are very very expensive. At least in aviation fuel service, they have a good track record of long life, normally there's other things that are breaking in the system instead of the DBB valve.

If you define corrosive environment they can apply necessary coating. SS Body can also be provided but with high prices and long lead times.
Dirty service ia wide scope. Better to be specific. Like RVAmeche mentioned mostly used in Oil&Gas. Storage, crude oil, refinery, terminals etc.
SEaling is non-metallic so corrosion would not be an issue. While valve is operationg the seals never scracth with any surface which brings the advantage to the design.
Valve is called plug valve but not very close to regular rotary plug valves so approach with a different view.
> bit late but I hope helps in anyway.

is this valve works in corrosive environment? [ If you check with them, they can advise on necessary coating or material selection for the corrosion ]

if this valve being plug if process medium is not clean( works in dirty service)? [ The valve is mainly used in clean On-Off services, and abrasive media can damage the elastomer seals causing a leak.]

how is the maintenance of the valve? compare to traditional plug valve? [ Franklin plug valve is not as maintenance-heavy when compared to a lubricated plug valve. You can reference their IOM to get an idea of maintenance requirements. Please note Franklin expanding plug valve is not the same as the traditional plug valve. You can check youtube to see videos that show how the valve works. ]

in valve catalogue mentioned "During rotation of the plug there is no abrasion or wear between the sealing surfaces." what if the corrosion cause sealing to fail? [ As dragos12 has stated, the valve has elastomer seals, metal components/coating can be selected depending on what corrosion you are looking at and factory offering]

Hope this helps

It's a Cameron General twin seal rip off. So anything you find out from the twin seals would apply.

It's the god valve when it comes to complete isolation in metering station (midstream) due to tight seal off and long life. I am not encouraging you to do it, but you could ask Cameron for help and then cross shop. General Twin Seals typically have horrible delivery, so that's on them.

Luke | Valve Hax | https://valvehax.com/