API 620 Verifying for Maximun Allowable Working Pressure

[JoeBPR]

Greetings,

I'm verifying some storage tank MAWP's of which some are 650's and some are 620's. Now the 650 were basically straight forward because they have an explicit formula for MAWP but the 620's don't, that I know of. Does anyone know a way to solve this problem? Remember I already have the tanks, I want to verify if the pressures that they are designed to work to are correct.

Thanks,
Joe

 

[JStephen]

You can solve the problem by applying the design provisions of API-620. There's not a good shortcut. If you have the tanks but don't have design drawings, it may be difficult to verify.

API-650 has formulas for maximum pressure, but they have also changed up the way pressure and seismic and wind interact, and have some contradictory formulas in different sections, so it's not as clear-cut as you make it sound.

 

[48jeep]

Not that having the drawing always makes the process straight forward. Reading scanned copies of blueprints from antiquity has proven less useful than going out with a tape measure on at least one occasion for me. That, and drawings have been known to be straight up wrong.

Not that you wouldn’t be as familiar with that as me Joe.

 

[Duwe6]

And while 'taping' the tank, take a representative set of thickness measurements. Not at all unusual to have to recalc a tank, starting with zero data.