ASME Code VIII vs. API 650/620
ASME Code VIII vs. API 650/620
(OP)
I'm working on a project for a oil refining company and the Project Management Consultant did a basic engineering and produced some equipment data sheets for tanks which store recovered oil and some kind of liquid organic waste and so on. As design code ASME Code VIII was specified. Now the contractor released new data sheets and indicates design code API 650/620. The tanks are under a nitrogen blanketing but almost with atmospheric pressure.
Are there any objections against API Code ? Is the qualty of tanks fabricated according API less than ASME ?
Are there any objections against API Code ? Is the qualty of tanks fabricated according API less than ASME ?





RE: ASME Code VIII vs. API 650/620
I the design pressure of the nitrogen blanket is such that it falls within the limits of API 650 then there is no objection to using the API Code for storage. Obviously a Vessel to ASME VIII is better, quality wise, than a storage tank to API 650 but you should be selecting the correct Code for the desired equipment.
RE: ASME Code VIII vs. API 650/620
API-650 is applicable to flat-bottom vertical tanks, with pressure up to 2.5 PSI. API-620 is applicable to tanks with a vertical axis of revolution, up to 15 PSI. Neither is applicable to horizontal tanks or leg-supported tanks.
If the tanks are flat-bottom and of any size, I doubt they COULD be built to ASME Section VIII.
We sometimes see Section VIII specified for design, but not necessarily as a construction code, for non-pressured tanks or low-pressure tanks. Look at how this was worded in your inquiry.
As a contractual issue, I'd suggest you review your bid documents and their quote to see what was actually proposed. You may also have legal requirements where you are that specify that tanks must be built to API or ASME standards. And if it's a tank that cannot be built to ASME code, then you'd expect API.
There are differences in the design, detailing, inspection, material requirements, etc., between the different codes/ standards. If the configuration, pressure, and application fall entirely within API-650 or API-620, you're probably better off using it. ASME Section VIII is just a mess compared to API-650 or API-620.
RE: ASME Code VIII vs. API 650/620
I certainly do not agree that the quality of an ASME VIII vessel is obviously higher than that of an API-650 or 620 tank. The perceived quality of an ASME Code-Stamped vessel is way over-rated.
Steve Braune
Tank Industry Consultants
www.tankindustry.com
RE: ASME Code VIII vs. API 650/620
Any help you all could provide would be greatly appreciated.
RE: ASME Code VIII vs. API 650/620
You didn't say how big the tank is. Up to 30,000 gallons or so, you're probably best off buying a shop-built tank, whether vertical or horizontal. If the capacity is much more than that, you would probably want to go with a vertical flat-bottom tank. (Or could be a suspended bottom if it was that critical). Would it extend the time if you added more corrosion allowance on the bottom? 1/2" bottom plate wouldn't cost too much on a small tank.
RE: ASME Code VIII vs. API 650/620
You're joking, right?
RE: ASME Code VIII vs. API 650/620
Im sure you, as have many of us, have seen horribly constructed ASME pressure vessels and very well constructed API tanks.
Is an average ASME pressure vessel without any additional inspection usually higher quality construction than an API tank with the same inspection? Probably so. However, its all about the specifications and the non-mandatory (by code) inspection that is required by the owner.
I tend to agree with Stephen. The quality of a code stamped vessel is overated. Its a great place to start and can result in a quality piece of equipment if properly supplemented with good design and inspection, but I have seen far too many piles of jumk leave ASME code shops to be fooled into thinking that an ASME stamp means your are getting a well constructed piece of equipment.
RE: ASME Code VIII vs. API 650/620
The size of the tanks will be 12,000 gallons. I think I'll stick to my original thought of buying the shop built (UL 142) tanks. The cost is much less than an API or ASME tank and should work fine for a blanket pressure of less than 3/4 psi. After speaking with the tank manufacturer, he stated that for vertical 142 tanks, they pressure test up to 1.5 psi and for horizontal they take it up to 2-3 psi with flat plate ends.
RE: ASME Code VIII vs. API 650/620