Minimum Height from Bottom Tank to Nozzle Center Line

[TengkuSyahdilan]

Dear Mr n Mrs,
I want to ask, is there any Code or Standards that specified about Minimum Height from Bottom Tank to Nozzle Center Line? Where can i find it? In my case the Nozzle is for Pipe 6 Inch, what is the minimum Height from Bottom Tank to Nozzle center Line?
Thank you Very Much

Best Regards

Tengku Syahdilan

 

[europipe]

It depends on what purpose but
look at standards API620 or 650.

Greetings

 

[TengkuSyahdilan]

This tank are for diesel and fuel oil storage and distribution. The tank are design according To API 650. I have read in API 650 that nozzle height from bottom of tank for 6 inch nozzle is 275 mm, but i also had seen in some project with same tanks and same size of nozzle they put 339 mm from tanks bottom. i want to make sure of this cause i have to routing a line from centrifugal pump to this tank with size of pipe 6 inch and i have a problem that if we put center line of nozzle tank at 275 mm from tank bottom then the center line of pump suction nozzle will be higher than CL of outlet tank. So what is the minimum height from tank bottom to tank nozzle CL for 6 inch pipe?

 

[europipe]

Don't exactly know what You mean , but when the constuction is right You can put the nozzle anywhere you like,
even under the tankbottom.

Greetings

 

[TengkuSyahdilan]

So from your comment i can say that there are no standards rules for minimum height of center line Nozzle tank from the bottom of tank or top of tank foundation. Ok thank you very much.

 

[Montemayor]

TengkuSyahdilan:

Unless you are located in a country or region where the law prohibits you from deviating from the API standards or restricts you to certain nozzle locations and orientations, then you can put the pump suction nozzle anywhere on the tank shell as long as you don't defeat or jeopardize the structural integrity of the tank.

euroipe is correct. The API standards are just that; they ARE NOT RULES or codes (unless applied as such by YOUR local authorities). In fact, the API offers a flush bottom nozzle design (rather expensive to buy and install) that puts the nozzle at the very bottom of the tank. I always build and install my own flush bottom nozzles by using an eccentric welding reducr. I "slice" a portion of the "belly" of the eccentric and weld this section (together with the large OD part) to the tank's bottom shell and a bottom plate extension. It works just as well as the API design and is much cheaper and quicker to install.

 

[gmax137]

This subject is really outside the things I normally work on, but, are there important reasons for elevating the nozzle above the tank bottom? - allows foreign material a place to settle, affects vortex formation, ???

 

[IFRs]

API 650 is very clear on the minimum nozzle elevations. There are tables and also weld spacing charts. Yes there are flush nozzles but in between the lowest height and the flush nozzle elevation is a range of not allowed elevations. API 650 is often enforced by the regulatory bodies. In any case if you follow API 650 your risk management people will be happy and your insurance company will be happy and your neighbors will be safer.

 

[Montemayor]

IFR:

There is no safety issue that has been raised on this topic. The query is: can a pump-out nozzle location be lower than that indicated by the API Standard?

The answer is logically (& correctly): YES.

As I have noted, even API standards accept (& recommend) a bottom flush connection. In fact, I didn't even mention that you can also apply a tank floor, internal box sump. Is that ALSO not considered a "safe" feature? In 48 years of applying API standards and RPs (recommended practices) I have yet to meet or hear about any insurance agent, inspector, or unfriendly neighbors that can challenge me and the logic I've used on all the API tanks I've specified, sized, installed, & operatted. My point here is that the API standards are many times very general; but they are meant to help rather than hinder an application. They are based on common engineering sense and sound safe practices. Unless you have serious and specific safety concerns and arguments, I have found the API and insurance inspectors to be very cooperative and understanding in how you apply the API standards.

Contrary to what your last post alludes, there is nothing inherently UNSAFE about a nozzle located lower than that depicted in an API drawing - unless a credible and possible hazardous scenario can be described related to such a nozzle location. (And we know that will never be the case as long as the API fosters a flush, bottom-floor nozzle design - as they do). The important point is ALWAYS a safe and dependable engineering design. However, unless we have an API representative that can prove that a specific nozzle location is SAFE or UNSAFE, we can't take expert license and state such a claim.

The API is not going to do OUR logical and safety-related thinking for us. WE are paid to do that and held liable for the ultimate design and application. The API disavows any design responsibility for any application results. No one is going to even try to hold the API liable.

I hope my comments on this subject are not being interpreted as being unsafe design - and consequently a danger to the Original Poster (OP).

 

[IFRs]

My answer to the OP remains: API code specifies the lowest height a nozzle can be in the tank shell.

If you want to do a special design with proper analysis then sure, you can do anything you can technically defend. I did not interpret the OP's question that way.

Flush nozzles are also in the API code as you so clearly and repeatedly declare. That fact does not suggest to me that any height nozzle is within the API code. Please show me where API has nozzles below low height and above flush.

In terms of safety and risk management, if you have a tank failure but you designed and built in strict accordance with API code, your liability will be much lower and your cost to defend your design will be easier. As you are obviously aware, the corner weld is one of the most critical joints in a tank. Placing a penetration lower than API low height but not a flush type would increase the risk of failure beyond my comfort level without some pretty fancy design work and possibly testing. You would need a pretty darn good reason to spend all that effort!

Another issue with non API penetrations: after the tank changes hands and the design backup is lost, how will the next inspector and owner satisfy themselves that the tank is safe to operate? API 653 does not offer much guidance there, or does it?

 

[IFRs]

Back to the OP's original post, API 650 11th edition addendum 1 table 5-6a lists the low height for a 6 inch nozzle to be 200MM assuming that the weld spacing of section 5.7.3 is also met. Done.

 

[TengkuSyahdilan]

Thank you to all valuables input. I'm here talk about the height of tank nozzle from the tank bottom at the tank shell. I want to put the nozzle higher than 200 mm that list at table 5-6a API 650 11th edition addendum 1. So with this i can routing the line from this tank Nozzle to our pump suction nozzle. I want to put the outlet of tank higher than the pump suction nozzle. The conditions right now if we positioning the tank outlet nozzle at 200 mm, the tank outlet will be lower than the pump suction, even if we put it at 350 mm from the tank bottom at the tank shell.

 

[IFRs]

Higher is no problem! The elevations are minimums! The reason for the minimums is to keep the hole in the tank shell above the corner weld far enough to allow for adequate reinforcement and weld spacing.

 

[europipe]

And when you want to pump up more fluid from the tank, add inside an elbow downwards plus a piece of pipe when neccesary.

 

[786392]

Even having sumps in bottom for emptying out and pump-out nozzles extended into such sumps below Tank's normal grade level should be really helpful

Best Regards
Qalander(Chem)