There does exist flexible PVC, and it looks like it can be solvent welded much like rigid pvc. But, I'd bet its flexibility causes some inherent weaknesses vis-a-vis rigid pvc of the same rating. These factors might affect where it can be approprately used.
Where are you planning to use it?
FWIW, I got this from a manufacturer's website:
"When is "schedule 40" not schedule 40? Our flexible PVC is treated as a hose by the building industry, not a pipe. Thus our hose fits Schedule 40 fittings (dimensionally) and can be used in place of schedule 40 pipe for many applications, but it does not meet all the requirements for schedule 40 pipe...The pressure ratings are not the same as schedule 40 pipe...So, while we call it "flexible pvc pipe" in reality it's a hose that fits perfectly into schedule 40 fittings, but it can't meet the most stringent "schedule 40 pipe" requirements."