Gary, what about re-certification of the large horizontal RV propane tanks? No one I ask, RV dealer or propane dealer, seems to know. Required or not? Doug C., (Peachtree Corners, GA)
Doug, in the US, only DOT (Department of Transportation), cylinders require periodic inspection and recertification. The same for Transport Canada cylinders north of the border. That said, the industry does manufacture a horizontal DOT/TC cylinder, like this one on the right.
But I don't believe it's the horizontal DOT/TC cylinders you are inquiring about. I'm guessing you're concerned about those larger, horizontal propane containers typically found on motorhomes, like this one on the left.
The rules for this type of propane container are governed by ASME (American Society of Mechanical Engineers). ASME tanks are not required to be re-certified since they are permanently installed. But DOT/TC cylinders, both vertical and horizontal, because they can be removed, transported and filled independently, do qualify for periodic re-certification.
All propane containers, tanks and cylinders, however, should be periodically inspected, cleaned and tested for leaks. All of which should be considered preventive maintenance common sense.