Ukmet:
PD5500 is a basic code/std. for unfired pressure vessels, right? Probably a pretty good std. of practice (for design and fabrication) for many different pressure vessels, and a basic reference for many more detailed/ specific codes/stds. Then, the exceptions/exclusions, etc. probably have to do with the over-the-road transit, Dept. of Transportation (DOT) and Environmental Protection Agency (EPA), or your variation of those agencies. That’s where I’d start looking. Maybe ask some of your competitors or clients what specs./codes/stds. apply to this type of equipment.