Old tank repair to current API 653 ; what API 650 version to address 1

[FrCivEng]

This is an existing API 650 tank which floating roof is to be replaced ; current API 653(3rdEd_Dec2001_Add3_Feb2008_Err_Apr2008) will govern the repair design and works ; when the API 653 addresses the API 650, what is the API 650 version to be considered ?
Is it the one which governed the tank original design and construction or is it the current API 650 11th Ed ?
Thank you for your help

 

[Bonswa]

When a repair sends you back to the "Original" construction code, you are to use the edition and addendum of the code that is stamped on the tank.

If the nameplate states API-650 10th Ed, Add. 2, that is the code that is to be used. Use whatever code that is stamped on the nameplate.

So, basically, if you can find your original construction drawings and procedures, you can simply tear out the old roof and replace it "in kind" using those drawings.

you can incorporate some of the practices in the newest edition as long as they meet or exceed the criteria outlined in the original design code.

Hope this answers your question.

 

[kwaliteitshenk]

Can or will anyone supply me with an (old) (electronic) version of the API 650. Just for information to see the differences between the EN 14015 an the BS2654.

Thanks in advance

 

[IFRs]

Which edition / addendum ?

 

[JoeTank]

I disagree with Mr Bonswa. It is the intent of API-653 that all new work be in conformance with the current edition of API-650, not the as-built API-650.

Joe Tank

 

[IFRs]

API 653 says

1.1.5 This standard does not contain rules or guidelines to
cover all the varied conditions which may occur in an existing tank. When design and construction details are not given, and are not available in the as-built standard, details that will provide a level of integrity equal to the level provided by the current edition of API Std 650 must be used.

Also:

12.3.2.3.2 New materials used for the repair shall meet the
current edition of API Std 650 requirements.

API also answered the following inquiry:

Question: Given that an inspection in accordance with API Std 653 is pending for selected tanks constructed in accordance with the 7th Edition of API Std 650, are these tanks required by API Std 653 to be upgraded to meet the requirements of the current (11th) edition of API Std 650?

Reply: No. However, if there is a change in service involved, or there is a reconstruction, repair, or alteration required, then the requirements in API Std 653 generally invoke the current edition of API Std 650 for the evaluation/construction work required. Refer to the appropriate sections in API Std 653.

Hope this helps reinforce JoeTank's reply.

 

[Bonswa]

If that's the case, then, it depends on wether or not he has the original construction drawings, which I assumed he did..... like you cited below:

"When design and construction details are not given, and are not available in the as-built standard, details that will provide a level of integrity equal to the level provided by the current edition of API Std 650 must be used."

IF the as-built drawings are not supplied, THEN you would use the current standard. ONLY IF THEY'RE NOT AVAILABLE. that's why i stated in my post that "if you can find your original construction drawings and procedures, you can simply tear out the old roof and replace it "in kind" using those drawings."

If he has the as-builts, then he would use them, which would conform to the ORIGINAL 650 used.

so... the question is to FrCivEng. Do you have the original construction drawings.

 

[kwaliteitshenk]

IFRs. Edition 9 or 10 will do. Just to compare crompression area calculations.

 

[Bonswa]

That brings up another question to FrCivEng.....

What type of roof is it? internal or external?

From API-653:

9.12.1 External Floating Roofs

Any method of repair is acceptable that will restore the
roof to a condition enabling it to perform as required.

9.12.2 Internal Floating Roofs
Repairs to internal floating roofs shall be made in accordance with the original construction drawings, if available. If the original construction drawings are not available, the roof repairs shall be in compliance with the requirements of API Std 650, Appendix H.

 

[Bonswa]

So... there it is again... if you've got the original construction drawings, you must replace the roof according to those drawings.

 

[IFRs]

Part of the confusion might be that tank repairs have to meet current code but floating roof repairs may not have to. On the other hand, changes in the floating roof portion of the code are good ones that give you a better product for little increase (if any) in cost. If you are only gong back to 9 or 10 then the changes are minimal.

Bonswa has a good question - internal or external floating roof?

 

[Bonswa]

It's funny, because your name ( IFR ) is the reason that i thought of internal floating roof or external floating roof.

 

[IFRs]

My "name" is indeed an acronym for internal floating roofs as I have been in that business since 1977, is the field I hold my only two patents, and have either designed and built or repaired most if not all the types out there. Back in 2002 when I joined this forum, I was nearly 100% into floaters and tanks. While my engineering life has led me in many other areas, I still continue to be active in floating roofs and have not bothered to change my moniker.

In any case, we await the OP's answer as to hiw particular situation - external (Appendix B) or internal (Appendix H). The code for externals has changed much less than that for internals (I participate on the API committee responsible for maintaining 650).

 

[JoeTank]

Again, I cannot agree with Mr Bonswa's responses. IFR replacement must comply with the current Standard, not the original one. The replace in-kind statement was included to allow for fact that IFR design procedures are not available in API-650 or API-653. As such, the as-built drawings would be a good repair source. For an IFR replacement, it does not matter whether the original IFR drawings are in hand or not. A new roof must comply with the current Standard. FrCivEng states that this is a roof replacement, not a repair.

Joe Tank

 

[IFRs]

Joe is quite right. New work must meet current codes.

 

[Bonswa]

IFR design procedures are available in API-650, app.H titled "INTERNAL FLOATING ROOFS"

If i'm going to partially replace a floating roof or completely build a new one, I'm going follow the original construction drawings. I dont understand why you would choose to change the design of a tanks roof if it's not required and is functioning properly.

When the entire tank was originally designed, the floating roof that works WITH the rest of the tank is included. I would not change that design. if it is already approved of and has no flaws that affect the operation, then it would be a replacement in kind.

I understand completely what you're saying, though. It's almost like you're looking at the tanks shell and floor completely seperate from the roof. they were all designed together, at the same time, for a reason. you cant consider a roof replacement to be "new construction". It's a repair, even if you're replacing the entire thing. you're repairing a part of the tank.

The ONLY time that i have seen your situation is when a pan type or other IFR is removed and replaced with a pontoon deck or aluminum IFR. In those cases, i agree 100%. it's never been designed for that tank, it MUST conform to the current version of the standard. In those cases, the IFR was designed seperately from the rest of the tank, therefore two different editions of 650 were used and two different nameplates were attached to the tank.

If that same pan type IFR is being removed and replaced with another pan type IFR, i'm going to use the original construction drawings, because that's what the tank, roof included, was designed for; and that conforms to API-653.

I would like to see, cited, where it says that replacing a floating roof is considered "new construction". yes, you CAN design a new roof and make it acceptable to the current 650 standard, however it IS NOT required. A replacement in-kind is definitely a repair, which constitutes using API-653 guidlines, which point to the as-builts (if available):

"When design and construction details are not given, and are not available in the as-built standard, details that will provide a level of integrity equal to the level provided by the current edition of API Std 650 must be used."

 

[IFRs]

Herein lies my opinion. This is not meant to be a criticism of any kind. I do not mean to lecture, toot my horn or belittle any of the previous posters. What follows is my personal opinion, not a declaration of right or wrong.

If the roof were to fail and it was determined that you designed it to out of date codes (replicating what was there), in my opinion, you would be exposing yourself and the owner to an unacceptable risk and putting yourselves in a relatively undefendable position should the need arise.

As engineers, protecting the public safety is job one even if it means being slightly conservative. In this case, the failure (sinking) of an IFR would allow the vapor space above the liquid surface to become rich, possibly passing through the explosive range. A lightning strike or passing cloud could ignite the mixture, causing quite a spectacle. This has happened. Even if there were no major incident, disposing of possibly contaminated product, cleaning the tank and fixing the IFR is likely to be way more costly than building per current code now.

It's just not worth the risk, in my opinion, considering that the newer codes are not so different that the cost to meet them would be terribly significant.

I also think you may find contractors reluctant to build new (replacement) IFRs to older codes. If you find one that will gladly do it, I'd watch out!!

Again, I apologize if I have offended anyone.

 

[JoeTank]

FrCivEngr,
If one chooses to ignore the clearly defined requirements that the new roof comply with the current Code, you are going against the very basic tenants of API-653. Everything else in the Code says use current edition of API-650 as the basis of repairs and alterations. Why would a new IFR be the only exception? Installing a new IFR to an old code edition means that the current code requirements may not be met. I can think of a few recently added requirements for IFRs that older editions would not meet. Just for the record. API-650, Appendix H does not provide any design procedures for the design of an IFR. It only provides design loads and some design criteria. The specific details of the design procedures is an expertise that is typically resident with the IFR manuafacturer.

Joe Tank

 

[Bonswa]

No offense taken. You guys know how it is when it comes to interpretation of these codes. I'm sure you've gone back and forth with co-workers over the same things.

When answers are not CONCRETE with these codes, and they are left open for multiple interpretations, it's debatable.

In my experiences, the Owner/User has always made the call to go with the original construction drawings when tearing out roofs and building new. Knock on wood, none of them have had any failures when going this route that would bring up this topic.

Joe... is your reply limited to IFR's? My replies have mainly been aimed at EFR's, as i'm more familiar with EFR's than IFR's. Do you still disagree with my argument, being that they are aimed at EFR's?

The Owner/User, that I have settled down with, has just done MAJOR work to two of their 250ft crude storage tanks, two years ago. One tank has had then entire floor replaced, as the foundation had TONS of clay (ate right through it). Both tanks had the external floating roof completely removed from the tank. The new roofs were built using the original construction drawings. There were only MINOR modifications made to it (pontoon cover design, satellite roof drains added...). None of the modifications were made specifically to comply with the LATEST edition of 650. The modifications were based strictly on the operation history (roof held rain water, pontoons were difficult to open during seal inspections).

This is definitely a topic that i will bring up to my current Owner/User to see what kind of research they've done to make sure that their EFR replacements were "acceptable".

 

[IFRs]

Not much has change in appendix B External Floating Roofs that would affect the structure or basic design. How hard would it be to review it? In probably less time than you have taken on this thread you could have read it and compared it to the earlier code or the original design.

Even without the code issue, I might review the leg strength, buoyancy, well height, rim height, seals, etc if nothing else than to make sure the original drawings did not have inadvertent errors.

Also note that in the USA the EPA rules for seals may have changed and you surely would not want to run afoul of them.