FMCSA
Cargo Tank Facility Search
Look up whether a facility is registered and what it's registered for.
FMCSA's public registry of registered cargo tank facilities.
Use it when you need to know whether a shop is registered before you send a tank there. It also shows what functions a facility is registered to perform, which is not always what a shop tells you it does.
If a shop doesn't come up, that's worth a question, not a conclusion — records update on their own schedule.
This tells you what's on file. It doesn't tell you whether the work is any good.