Tuesday, November 10, 2009

API 650 11th Edition Addendum 2

Addendum 2 to API 650 11th Edition has been released. The effective date for this addendum is May 1, 2010. I will give just a brief overview of some of the bigger changes. I will do a more complete review later. First, they have changed Tables 5-6a and 5-6b and revised the minimum distance from the bottom of the tank to the center of a nozzle for regular type fittings. Snow load requirements have changed such that you now will have to consider both balanced and unbalanced snow loads. In Appendix V that have changed the stability factor such that there are different values depending upon certain conditions. The one that surprised me the most is that they slipped in Appendix Y. This was added after the proof copies were sent out. Appendix Y has added back into the standard the API monogram system. It appears that you can now place the API monogram on a tank nameplate if you have been certified to do so. You may find in the future that some companies will require this certification to be able to bid on and build their tanks. It will be something to watch out for.

Tuesday, October 27, 2009

Seismic Av and TL values

The question comes up as to what is the Av and TL values in our ITSdesign program? These values are listed under the seismic input section on the design page. Av is the vertical acceleration value and is entered as a value of g. This input is different than the Ss and S1 values which are entered as a % of g. In API-650 it is up to the client to specify if a vertical acceleration is to be included in the seismic calculations. If it is, they are to provide this value. In AWWA D100 there is a minimum value that is to be used based on the other seismic values. A client can specify a higher value though.

The second value, TL, is the Region-Dependent Transition Period for Longer-Period Ground Motion. This value depends upon the location of the tank and can be 4, 6, 8, 12, or 16. Areas from Eastern Texas to Eastern Kentucky and from Central Minnesota to the Gulf Coast are listed as a 12. The Northeast states are a 6 while the Southeast states down to Florida are an 8. The Southwest is a 6 and the upper Midwest is a 4. West of the Rocky Mountains it is a 6, 8, 12, or 16 depending upon your location. AWWA D100 printed the map of these values in the seismic section, Section 13 Figure 19. Unfortunately, API 650 did not include this map in their standard. If you do not have the AWWA D100 standard, you would need to look in ASCE7 for this map.

Wednesday, August 26, 2009

Jack Rafter System

We have just released a new version of ITSdesign that has a Jack Rafter System. This allows you to use a single center column on tanks as large as 90' to 100' diameter. With this system half of the rafters go from the center column to the shell. In between each of these Thru Rafters is a Girder that is made from a small channel and is located at approximately the mid point of the Thru Rafter. From the center of the Girder to the shell is placed a Jack Rafter. Thru Rafters get to be quite heavy but the Jack Rafters are relatively small. It does increase the load on the center column and on the soil below the column. However, the cost savings can be significant as you do not need intermediate columns. It also reduces the diameter of the cap plate on the center column considerable. The erection cost for this type of system is less than for one with intermediate columns.

If you haven't downloaded a free trial copy of ITSdesign, do so today and give this new system a try. Just go to www.innnovativetanksolution.com and click on the ITSdesign download button. Follow the instructions for installing the trial program.

Tuesday, June 16, 2009

Frangible Roof Design

Some of you have been asking when we would be releasing a version of ITSdesign with Frangible Roof Designs. We have just released that version. Yes, we now have Frangible Roof Designs in accordance with Addendum 1 of the 11th Edition. There are four different sets of requirements in The first is for tanks that are 50' in diameter or greater. The second is for tanks 30' in diameter but less than 50' diameter and self anchored. The third is for tanks less than 50' in diameter and self anchored (this requires an elastic analysis). The fourth is for tanks of any size that are anchored. ITSdesign includes the first, second, and fourth options.

We continue to add to our program. If you have not seen what our program can do, visit our website at www.innovativetanksolution.com and download a trial version. We look forward to your comments and to the next addition to our program.

Friday, June 12, 2009

API-650 11th Edition Addendum 1 Appendix F

An interesting thing has occurred with the design in API-650 11th Edition Addendum 1 with regard to Appendix F. With the changes, the design is now based on the yield strength of the material. When you look at the formula for P, the internal pressure, you will see that you have AFy which is the area times the yield strength. At first glance you would think that this will help you when you high strength materials. And in reality it does IF the shell, roof, and compression ring are all high strength material. However, if the shell and roof are high strength material and the compression ring is A36 material, then you have the same pressure as before. The yield strength, Fy, in the formula is based on the lowest yield strength of the compression area. Therefore, if the compression ring is the lowest yield strength, then that is the value you use.

An interesting thing occurs when you start looking at the area, A. The amount of area available in the shell and the roof have not changed. Those formulas are not based on the yield strength of the material. What did change is that the amount of area in the horizontal projection of the compression ring is based on the yield strength of the compression ring when the horizontal leg is not stiffened. In the previous editions this value was 16t. Now (in US units) it is the thickness of the material times 3000/(Fy)^0.5. Here is a list of what happens to the horizontal projection allowed (Le) for a thickness of 1/4".

16t = 4"
A36 material (Fy = 36000 psi) = 3.95"
A678A material (Fy = 50000 psi) = 3.35"
A240-304L SS (Fy = 25000 psi) = 4.74"

As you can see, the higher the yield strength of the compression ring, the smaller Le can be which reduces the area, A. Thus, if you used a high strength steel for the compression ring and the shell but used a low strength steel for the roof you will end up with a lower allowed internal pressure because the compression ring will not contribute as much area and the yield strength of the roof will be the governing value for Fy in the pressure formula.

If you really want to scratch your head about something, think about this. I could build a tank using a material with a yield strength of 50000 psi for the shell, roof, and compression ring and have it meet the frangibility requirements of However, that same tank with the same thicknesses using a material with a yield strength of 36000 psi for the shell, roof, and compression ring would not necessarily meet the frangibility requirements of (area of the compression area could be greater for the lower strength material).

Thursday, May 28, 2009

API Committee Meeting

There was a lot of discussion going on at the API Committee Meetings held the end of April. Some of it had to do with floating roofs and some with the wind loadings especially on uplift on the roof. Neither has been resolved and both are on going discussions. They are working on doing some testing for the wind uplift situation to try to resolve the conflicts.

With regard to API-650, the following agenda items were approved for publication.
1) Added shell nozzles in pipe sizes 50", 52", 54", and 60".
2) Added long welding neck flanges and lap joint flanges as acceptable flanges.
3) Revised some dimensions of flush cleanouts.
4) Revised the anchored and unanchored tank calculations in 5.11.2 and 5.11.3 to include a pressure combination factor applied to the internal pressure portion. Also added this factor and revised appropriate equations in Appendix R.
5) Deleted the joint efficiency requirements in the equations in Appendix V.
6) Changed the required dome roof depth in Appendix J to be a "Minimum" depth instead of a "Maximum" depth.
7) Revised Appendix J material reference to read that the material requirements of Appendix A apply as long as the material is 1/2" or less in thickness instead of requiring the material to meet Section 4 requirements.
8) Revised Appendix J to allow thicknesses greater than 1/2" as long as the material requirements of Section 4 are met.

It was also brought up that in some cases the formulas in Appendix P.3 for the curves did not calculate out to the same as values plotted on the curves. After a lot of discussion it was decided to temporarily remove P.3 from the standard until the discrepency can be corrected either in modification of the curves or modification of the formulas.

With regard to upcoming addendums, we were informed that the next addendum for API-650 will be issued sometime this fall and will include all items approved for publication prior to the April meeting. The items approved at the April meeting as well as the next two meetings will be published in the addendum that will be issued in the fall of 2010.

We still have many items being worked on for the next meeting. If you have some items you feel need to be addressed by the committee you can address them to API or let me know and I will see if I can get them addressed at the next meeting.

Wednesday, May 20, 2009

API-650 11th Edition Addendum 1

It is now released! We have just released the revisions to ITSdesign to bring it into conformance with API-650 11th Edition Addendum 1. We have added a button so you can select whether you wish to use the 11th Edition or whether you wish to include Addendum 1. For Addendum 1 we have made changes to the Appendix F calculations as it now requires the use of yield strength of the material in the calculations. There are also changes to Appendix E to take care of adding a internal pressure factor in the calculation of J and changes in the calculation of annular rings. From the base code we have revised the check for maximum spacing of both inner and outer rafters, revised the check for minimum thicknesses in many places, and revised wind calculations. We have also added the requirements for duplex stainless per Appendix X. We will continue to add functions the ITSdesign program and will keep in conformance with the latest addendums.

Wednesday, April 8, 2009

Table 5-21a

It has been pointed out to me that I have an error in my previous blog concerning this subject. In it I stated that the multiplying factor 0.785 was left out. However, this factor should be 785. I double checked our ITSdesign software to confirm that we are using 785 and not 0.785. We are using the 785 factor. I will bring this up at the next API meeting to make sure this is corrected in the code.

Tuesday, April 7, 2009

ITSdesign Webinars Coming to Your Computer

Have you wanted to see how our ITSdesign software program before you downloaded your trial version? Have you wanted to have someone walk you through the ITSdesign program to show you how the various screens work? Would you like a live demonstration of the ITSdesign program? We will be starting to do live webinar demonstrations of our ITSdesign software. Right now we are setting up dates and times for these demonstrations. Within the next couple of weeks you will be seeing postings here on our blog giving dates and times we will be doing these webinars. The number of participants for each webinar will be limited and will be given out on a first come first serve basis. Check back to see when they will be held and how to sign up for one.

Thursday, April 2, 2009

Question on Table 5-21a

A question was asked concerning the formulas in Table 5-21a which is the Uplift Loads for SI units. The pressure formulas even in Addendum 1 to the 11th Edition have left out the multiplying factor 0.785 which is pi/4. Agenda item 650-646 revises the formula to include this multiplier. It also is revising the formulas in many other ways. ITSdesign uses the formulas approved in Agenda item 650-646. This was not approved soon enough to be part of Addendum 1 but should be part of the Addendum 2. I am not sure why this was not caught before Addendum 1 was published.

ITSdesign for 64 Bit Operating Systems

The PC computer industry is changing from 32 bit operating systems to 64 bit operating sytems. When the industry went from Windows98 to Windows XP operting systems we found that we had to modify our software to work on either operating system. The 64 bit operating system has been around for a while. However, it is just now that this operating system is becoming the standard rather than the exception. In looking at the computers available in retail stores, there are some 32 bit systems. However, there are an increasing number of 64 bit systems. In keeping with this trend, we have modified our ITSdesign software to work on not only Windows98 and Windows XP (32 bit) systems but also with the 64 bit systems. We have verified that ITSdesign will now operating on both the Windows XP 64 and the Windows Vista 64 operating systems. You can be confident that if you upgrade your computer to the 64 bit systems you will still be able to run our ITSdesign software. If you have not tried ITSdesign, go to our website at www.innovativetanksolution.com and download a trial copy.

Wednesday, March 18, 2009

API Committee Meeting

We have our spring committee meeting for the API aboveground storage tanks coming up the end of April. I have received several comments concerning errors in the current edition of API-650 including Addendum 1. There are other issues we will be discussing at this meeting. If you have some item of concern I would appreciate hearing from you. As a member of the subcomittee on design I am striving to help make corrections to the standards. I also wish to address the concerns of my clients with regard to the standard. I am currently working on an agenda item concerning Appendix J. If you have a comment concerning this Appendix, please let me know right away as I am trying to finalize the changes I wish to submit within the next week. You can email me your comments at jschroeder@innovativetanksolution.com. I will keep you informed as to what is happening with the committee.

Friday, March 13, 2009

API-650 11th Edition Shell Nozzles

They are completed!! Shell Nozzle Reinforcement calculations are now included in ITSdesign! Here is what is included:

1) Recalculate shell thickness requirements at nozzle elevation for both design (including seismic) and hydrotest conditions.
2) Calculate available area of reinforcement for both design and hydrotest conditions taking into consideration material grades and temperatures.
3) Evaluate weld shear loads for all paths of failure.
4) Check nozzle necks, reinforcing pads, flanges, and blind flanges for impact testing due to design metal temperature.
5) Check nozzles for stress relieving requirements.
6) Check fillet weld and groove weld sizes for compliance with the minimums in the standards.
7) Check weld spacing between the nozzle neck weld or reinforcing pad weld and the bottom to shell weld.
8) Check weld spacing between nozzle neck weld or reinforcing pad weld and the horizontal weld seam above or below the nozzle.
9) Check weld spacing between nozzle neck weld or reinforcing pad weld and wind girder or vacuum rings.
10) Check minimum required thickness of shell nozzle necks and manhole necks.
11) Check manhole plate flange and plate blind flange thicknesses taking into consideration liquid depth, specific gravity, internal pressure, temperature and machining allowance on flange.
12) Includes requirements for Appendix A, J, and S.
13) Evaluate up to 24 different nozzles.

Visit us at www.innovativetanksolution.com and download your trial version today.

Tuesday, January 20, 2009

API-650 11th Edition Addendum 1 - Part 3

Today we will look at the changes to the appendices. There have been some major additions.

1) Added Appendix AL - this is a complete section for the design, fabrication, erection and testing of aluminum tanks.
2) In Appendix B, they added section B.6 for tank foundations for tanks with elevated temperatures.
3) Added Appendix EC - a commentary on the seismic Appendix E including examples.
4) Revised Appendix F to use the yield strength of the material in formulas F.4.1 and F.5.1.
5) Appendix H added load combinations for floating roof supports.
6) Appendix M added a new paragraph M.3.3 to address the changes to to use Fy. This caused them to renumber everything below this. It appears that the new M.3.7 did not get changed to conform to the changes to Appendix F and will have to be modified.
7) Appendix S added that it is for a maximum of 200' diameter tank.
8) Appendix S added S.4.11.3 to allow the shop welding of narrow plate to form wider shell plate.
9) Added Appendix SC to allow mixed material (carbon steel and stainless steel) in the same tank.
10) Appendix V revised the maximum wind pressure formula, corrected various formulas, and added new formulas. The new formulas include the added stability factor. This sets the values for the stability factor and will require at least two different checks.
11) Added Appendix X to allow tanks built using Duplex Stainless Steel.

This covers most of the changes that are a part of Addendum 1. Some have minor affects. However, there are some major changes. We are working on incorporating these changes in our ITSdesign software and will keep you informed as to how that is going.

Thursday, January 15, 2009

API 650 11th Edition Addendum 1 - Part 2

Today we will continue with the review of the base code of API 650 11th Edition, Addendum 1.

1) In, they increased the maximum size of the outer peripheral weld on the repads in the SI units from 38 mm to 40 mm.
2) added that the reinforcing over the top of an opening shall be calculated for both the design and hydrotest condition.
3) A revision was made to both and to specify the basis for the thickness of the shell plate that can be used for the reinforcing calculations for flush type cleanouts and flush type fittings.
4) In 5.8.4 and, they added that the effect of loads other than normal personnel access applied at the roof manhole or rectangular roof opening and the supporting structure shall be considered and that the roof structure and the plate around the opening shall be reinforced as necessary.
5) revised the note for SI units to say that the minimum section modulus for the wind girder for tanks over 60m in diameter may be reduced but cannot be less than that required for a 61m diameter tank. (Seems like a bit of a problem here.)
6), frangible roofs, was revised. They also added requirements for 30' to 50' diameter tanks.
7), the requirement for rafter spacing was revised. They provided a formula to calculate the maximum spacing and set the maximum spacing to 84". This applies to all rafters.
8), the minimum thickness calculation now includes the the corrosion allowance for self supporting cone roof tanks similar to what was already in there for dome roof tanks. The one problem is that for dome roof tanks the formula has a >= sign while the cone roof tank has only a > sign. This will need to be addressed.
9) 5.11.2, they revised the calculation of MF for the wind overturning to include a formula for the maximum value equal to 0.90HD.
10) Tables 5-21a and 5-21b were revised. They will be revised again in the next addendum as these formulas have been corrected again.

These are the changes I have seen in the base code for design. Next time we will look at the various appendices including the new ones.

Monday, January 12, 2009

API 650 Addendum 1, Part 1

We have entered 2009 and I am finally getting around to talking about the changes in API 650 Addendum 1. There will be a series of posts to talk about the different changes, so come back and see what else is changed.

We will start with the basic code section.

1) There are many places where they simple changed the thickness specifed in the SI portion from 12.5mm to 13 mm. You will find this mainly in places where 1/2" maximum thicknesses is specifed such as for self-supporting roofs and in Appendix A.

2) The minimum thickness in many places was revised from 1/4" to 0.236" for conform to 6mm thickness conversions and from 5mm to 4.8mm for 3/16" thickness conversions. This is specified in 5.3.5. This includes such places as 5.4.1 for minimum bottom thicknesses, Table 5-1 for annular bottom plate thicknesses, for minimum thickness of built up stiffening rings, and for minimum thickness of structural.

3) They revised sizes of angles in the SI units in such places as (minimum top angle sizes), (stiffener ring requirements), and (top angle size required for open top tanks).

4) 5.2.1 b was revised to say that external pressure can be zero for tanks with circulation vents per Appendix H.

5) 5.2.1 also added loadings for internal floating roofs. Of course they could not add it to the end of the list, but had to add it near the beginning so they could renumber all of the items below it.

6) Revised to specify that if you use lower strength material for a upper course, the lower course must be at least as thick as the required thickness of the upper course for product or hydrotest or you must do an elastic analysis.

7) They revised most of the tables to separate the SI from the US and made them table a and b.

8) In Table 5-4, shell manhole thickness, they revised some of the thicknesses required for the higher shell course thicknesses and added for up to 45mm (1 3/4") shell plate.

9) In various tables it appears that they revised SI dimensions to conform to the US dimension conversions. This includes Figure 5-7a (shell manhole gasket and bolt hole dimensions), Table 5-5a (shell manhole bolt circle and cover plate dimensions), Table 5-7a (shell nozzles), Table 5-8a (shell nozzle flanges), and Table 5-9a (flush cleanouts).

10) Table 5-10a was revised to change the maximum design liquid level for flush cleanout flanges in SI units. They also revised the bottom plate thickness for the largest flush cleanout at the maximum liquid level for the SI units.

Next time we will finish up the changes to the base code.