ITSdesign

API 2000 Venting

2011-03-01T22:07:00.000-06:00

There is a new version of API 2000 for venting calculations. ITSdesign now includes this new edition for venting. There are two aspects to the new version of API 2000. The first is that to use calculations for venting that were in the previous edition, you must be using Annex A. Annex A does have restrictions that says the liquid stored must be similar to gasoline, the maximum operating temperature of the vapor space is approximately 120 degrees F (48.9 degrees C), the tank is uninsulated, and the capacity is less than 180,000 BBL (30,000 cubic meters). If it meets these criteria and you use Annex A, the results are the same as the previous standard. If, however, you use the base standard you will find that you need a lot more information about what you are storing. You need to know if the product stored is similar to Hexane, what is the Latent Heat of Vaporization of the product stored, what is the Relative Molecular Mass of the vapor, and what is the boiling point of the liquid at the relieving pressure. If you have insulation on the tank and you wish to reduce the emergency venting requirements because of the insulation, you need to know what the thermal conductivity is of the insulation. You also need to know what the approximate latitude is for the location of the tank installation. The answers to these questions could greatly affect the venting requirements especially for normal venting. It appears from some of our preliminary calculations that the normal venting per the base standard can be significantly higher than what is required by Annex A. We have just posted a new version of our ITSdesign software that includes these new calculations.

Insulation thickness added to ITSdesign

2011-01-20T09:57:00.001-06:00

We have just released a new version of ITSdesign that includes entries for insulation thickness and weights. You have the option of having insulation on just the shell, just the roof, or both. The insulation thickness and weight can be different for the shell and the roof. You can also specify as to whether the insulation weight is to be used in the resistance to overturning for wind and seismic calculations. The addition of insulation thickness affects the area of the tank exposed to wind. In the printouts for wind you will see a different value for the tank diameter and height when detemining the area exposed when the tank is insulated. This increases the overturning moment and the sliding forces. For seismic you will see an increase in the weights. Insulation thicknesses and weights are also shown in the printouts including in the loadings page.

Frangible roof design of anchored tanks

2011-01-18T09:39:00.003-06:00

At the API committee meeting in November I brought up the subject of the frangible roof design requirements. In particular I asked about the requirement if 5.10.2.6.d which says "For anchored tanks of any diameter, the tank shall meet the requirements of 5.10.2.6.a and the anchorage and counterweight shall be designed for 3 times the failure pressure calculated by F.6 as specified in 5.12." One of the requirements is in 5.10.2.6.a.5 which gives the maximum area of the compression ring that you can have and still be considered frangible. I asked if this requirement can be removed when the tank is anchored since we have to design the anchorage for 3 times the failure pressure which is based on the actual area of the compression area. After some discussion the committee as a group decided that you still must meet the area requirement of 5.10.2.6.a.5. What this means is that for smaller diameter tanks meeting the frangibility requirements is very difficult. For shop built tanks built to Appendix J meeting the frangibility requirements is next to impossible.

What is next in ITSdesign

2011-01-06T06:52:00.001-06:00

We are currently working on adding Appendix P.2 calculations to our ITSdesign software. It has turned out to be a bigger challenge than first anticipated and so is taking longer than expected to program. I will keep you informed as to the progress on this. With regard to Appendix P.3 that was deleted from the standard, the committee is still working on the review of the equations in relation to the charts. That work has not been completed and so we do not have a timetable for when this section will be put back into the standard. Since it is not ready for balloting as yet, it will be at least a year.

It is a New Year!

2011-01-03T18:46:00.002-06:00

Welcome to the New Year! My first post for 2011 will be about Addendum3 of API 650. Where is it? It is still in the process. I know it should have been released in November but it wasn't. In fact we have not seen the final draft of it to review. The last word is that it should be released in February or March. I am looking forward to its release as there are some changes in it to help with reducing anchorage on some tanks due to wind. As soon as I know it is being released, I will let you know and have the changes ready to release in our ITSdesign software program.

Buckling due to Wind in Corroded Condition

2010-09-16T10:30:00.001-05:00

For API 650 tanks the wind calculations (both resistance to overturning and for buckling) are performed in the new condition unless the customer specifies otherwise. As such we have always had a checkbox in the "Wind" portion of our design screen to specify that the wind calculations are to be done in the corroded condition. We have now added a second checkbox to allow you to do the resistance to overturning in the "new" conditiong but do the shell buckling analysis in the "corroded" conditiong. If this checkbox is marked, then the check for wind girders will be evaluated in the corroded condition rather than the new condition.

We continually make additions and modifications to our ITSdesign software to meet the needs of our clients. We have several modifications being evaluated or worked on because of requests received. A trial version of ITSdesign is available for download at www.innovativetanksolution.com.

API Committee Meeting

2010-09-14T10:17:00.000-05:00

The next API committee meeting will be coming up in November. As a member of the Subcommittee for Aboveground Storage Tanks design group, I will be attending the meeting and bringing some of my concerns and hopefully revisions to the standards. I have several issues I will be bringing before the committee. If you have a particular concern you think needs to be addressed, you can try to send an inquiry to API through their normal channels or you could email me your concern and I will see if it is something that I think the committee should be addressing. I would need any comments by the end of September. You can email me at its@innovativetanksolution.com.

Corrosion Allowance on Columns

2010-09-13T10:24:00.000-05:00

We have released a new version of our software that makes some additions to how corrosion allowances are handled for the columns of column supported roofs. Previously we applied the corrosion allowance to the outside only on pipe columns. For structural columns we applied the corrosion allowance to all surfaces of the beams. We have added a checkbox on the "Rafters & Columns" tab that allows you to specify that the corrosion allowance on pipe columns is to be applied to both the interior and the exterior. For structural columns we added a checkbox that allows you to specify that the corrosion allowance is the "Total" corrosion allowance rather than per surface. We also now note this on the "Design" page of the printout.

Factory Mutual 4020/4021

2010-09-10T10:04:00.002-05:00

We have just released a new version of ITSdesign that includes a design for Factory Mutual 4020/4021 (December 2005) tanks. This is currently only in US units as we are working on the conversions for SI units that Factory Mutual did not provide. The Factory Mutual design is still being verified by one of our clients to make sure that we interpreted all of the standard correctly. We will be making changes to this design if any discrepencies are discovered. Factory Mutual has two different options for seismic design using live loads. We chose to use the 25% of live load option. They also require that the sloshing height not exceed the freeboard or you must do an evaluation of the loadings on the roof. We currently have only included the option to require that the freeboard exceed the sloshing height. We did find an error in the equation in 2.15.5 (c) for the design tension load on bolts for seismic. The equation should be multiplied by S rather than divided by S. We have incorporated this in our program.

If you are doing Factory Mutual tanks we would appreciate your evaluation of the design. If you do not currently use ITSdesign software, go to our website at www.innovativetanksolution.com and download a trial copy of our ITSdesign software.

API 650 Approved Agenda Items

2010-06-26T21:35:00.002-05:00

We have just posted a new version of ITSdesign in which we did some minor corrections. One of those was to add the test pressure (1.25P) to the liquid height instead of just P for hydrotest when F.7 calculations are required. We also increased the allowable anchor bolt diameter for some grades of material and added A1554-105. We also did some other minor corrections.

The big change is that we have added several approved agenda items from the API committee meetings to our program. You must have client approval to be able to use agenda items that have been approved but not published in an addendum. These are items that will be published in the next addendum. Several of these affect shop built tanks as we have approval to use the materials at DMT listed in Appendix A without the impact testing. We also can build a shop built tank out of material thicker than 1/2". The other big change is changes in the wind calculations in 5.11 and changes in the formulas in Appendix F. These changes will have an affect on whether anchorage of tanks is required for wind and for wind/pressure combinations.

What Seismic Factor to use for Anchor Chairs?

2010-06-02T09:09:00.002-05:00

One of our clients brought up a disturbing point in API 650 Appendix E for Seismic designs. I have queried several engineers and reviewed this matter and am still confused as to how to apply this. The problem is as follows. In E.6.2.1.2 the last paragraph says that when you have a mechanically anchored tank, the anchor embedment or attachment to the foundation, the anchor attachment assembly and the attachment to the shell shall be designed for PA. It then defines PA as the lesser of the minimum yield strength of the anchor bolt multiplied by the as-built cross-sectional area of the anchor or THREE times PAB. PAB is given in equation E.6.2.1.2-2 and is the load on the bolt due to seismic. Now the problem. E.7 is Detailing Requirements and the paragraphs in E.7 apply when SDS>0.05g which happens to be any time seismic design is required. E.7.4 says that connections and attachments for anchorage and other lateral force resisting components shall be designed to develop the strength of the anchor or FOUR times the calculated element design load. Based on E.7.4 the value in E.6.2.1.2 should then be 4 and not 3. Until we can get a definitive answer from API on this issue, we have modified our ITSdesign software for Addendum 2 designs to use 4 instead of 3. For many tanks this will have no affect. However, for some tanks it will place an increased design load on your shell and could cause you to need higher chairs or thicker bottom shell plate. All comments on this issue are appreciated.

2010-05-06T07:02:00.002-05:00

API 650 Addendum 2 includes changes in roof designs by requiring a design for unbalanced snow loads. For column supported roofs this only affects the center column. If the roof slope is no more than 2 in 12, the unbalanced snow load per square foot is the same as the balanced snow load design. This does not affect rafters or girders. Also, the standard says that you do not need to include it for intermediate columns. The only additional requirement is that you have to check the center column for an eccentric load since the unbalanced snow is only on 135 degrees of the roof. This might cause a slight increase in the column size depending upon the loads.

Self-supporting cone and dome roofs have a new formula for checking unbalanced snow loads. Once again it can have an affect on the roof thickness depending upon the loads.

The biggest affect is on the supported cone roof without a center column that we have in our ITSdesign software. First, if your roof exceeds 2 in 12 pitch, then the snow load portion is increased by 50%. This will affect rafter sizes. The compression ring and tension ring are also affected no matter what the snow load is because of the unbalanced loading on the rings. To determine the stresses in the rings from this loading condition, a check at each rafter and between each rafter must be made to determine the location of the greatest tension load and the greatest compressive load on the rings. If you are using this configuration you may want to try to keep the roof slope to the 2 in 12 pitch. You will probably find the compression and tension rings are going to be larger even at this pitch.

Supported Cone Roof without Column

2010-02-08T19:39:00.002-06:00

We have just posted our newest version of ITSdesign. ITSdesign now has a design for a supported cone roof without a center column. This is available for AWWA D100 tanks and API 650 carbon steel field erected tanks (base code and Appendix A designs). The design includes the axial load on the rafter in addition to the bending loads. The center compression ring can be a standard channel, a channel shape fabricated from plate, or a bar shape. Loadings on both the center compression ring and the outer tension ring are evaluated. The rafters and center compression ring may be on the inside of the tank or on the outside of the roof. If they are on the exterior of the roof, they will have to be welded to the roof to transfer the loading on the roof plate to the rafters. This type of support system allows you to place the rafters on the outside of the tank when you have a interior lining on the tank. Also, if you have a tall tank this can eliminate the long center column. If you are not currently a user of our ITSdesign program, be sure to download our free trial version from www.innovativetanksolution.com.

API 2000 Venting

2010-01-05T18:48:00.002-06:00

Happy New Year! I will be trying to keep my New Year's resolution to blog more frequently. To start the year, let us look at what happens when API 2000 venting requirements are applied to a tank. My concern here comes about because of a tank I just designed for a client. The specifications said this tank was an atmospheric tank. Design and operating pressure are specified as atmospheric. All seems fine until we get futher into the specifications and come across the venting. In this section it was stated that the tank was to meet API 2000 venting requirements and provide the inflow and outflow rates. The rates are quite low as the tank is not very large. Even though the primary vent is to have a flame arrestor, the required pressure to provide the venting required for pressure and vacuum are both less than 1" of water. This had no affect on the tank. However, when we get to emergency venting the specifications said that the pressure required to provide full emergency venting could not exceed the design pressure by more than a certain percentage. Upon contacting the supplier of the emergency vent we discovered that we would have to design the tank for 4" of water pressure to meet this requirement based on the venting capability of the available vents. Needless to say this did have an affect on the tank design. We now have to anchor the tank for pressure where before the tank would not have required anchoring.

Venting requirements and the pressure and vacuum needed to meet these requirements can change the design of your tanks. A tank may be specifed to operate at atmospheric pressure. However, the venting and particular the emergency venting requirements may require the tank to be designed for pressure. Be aware of what pressure is required by the emergency and normal vents to meet the venting capacity. It may start relieving at a relatively low pressure but may require a higher pressure to meet the capacity required.

API 650 11th Edition Addendum 2

2009-11-10T20:38:00.002-06:00

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.

Seismic Av and TL values

2009-10-27T13:36:00.000-05:00

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.

Jack Rafter System

2009-08-26T19:59:00.002-05:00

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.

Frangible Roof Design

2009-06-16T20:00:00.001-05:00

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 5.10.2.6. 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.

API-650 11th Edition Addendum 1 Appendix F

2009-06-12T15:44:00.002-05:00

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 5.10.2.6. 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 5.10.2.6 (area of the compression area could be greater for the lower strength material).

API Committee Meeting

2009-05-28T11:36:00.003-05:00

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.

API-650 11th Edition Addendum 1

2009-05-20T13:09:00.000-05:00

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.

Table 5-21a

2009-04-08T11:11:00.003-05:00

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.

ITSdesign Webinars Coming to Your Computer

2009-04-07T17:23:00.000-05:00

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.

Question on Table 5-21a

2009-04-02T17:51:00.002-05:00

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

2009-04-02T17:12:00.002-05:00

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.

API Committee Meeting

2009-03-18T10:44:00.002-05:00

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.

API-650 11th Edition Shell Nozzles

2009-03-13T19:00:00.001-05:00

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.

API-650 11th Edition Addendum 1 - Part 3

2009-01-20T15:01:00.002-06:00

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 5.10.4.4 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.

API 650 11th Edition Addendum 1 - Part 2

2009-01-15T17:00:00.000-06:00

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

1) In 5.7.2.7, they increased the maximum size of the outer peripheral weld on the repads in the SI units from 38 mm to 40 mm.
2) 5.7.7.4 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 5.7.7.5(b) and 5.7.8.4(e) 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 5.8.6.1, 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) 5.9.6.1 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) 5.10.2.6, frangible roofs, was revised. They also added requirements for 30' to 50' diameter tanks.
7) 5.10.4.4, 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) 5.10.5.1, 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.

API 650 Addendum 1, Part 1

2009-01-12T13:11:00.002-06:00

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, 5.9.3.1 for minimum thickness of built up stiffening rings, and 5.10.3.2 for minimum thickness of structural.

3) They revised sizes of angles in the SI units in such places as 5.1.5.9 (minimum top angle sizes), 5.9.3.1 (stiffener ring requirements), and 5.9.3.2 (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 5.6.1.3 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.

API 650 11th Edition, Addendum 1

2008-11-10T17:49:00.002-06:00

Can you believe it? It has been released! Addendum 1 to the 11th Edition of API-650 is now available! Now we can begin looking at what has changed. Since it has been indicated that there where a lot of editorial changes between the proof copy I had and the released copy, I will start over letting you know what changes have been made in the Addendum 1. We will also begin making revisions to our program to incorporate these changes into our ITSdesign program. The release date on the addendum is November. Therefore, the mandatory effective date will be May, 2009.

API Inquiries

2008-10-30T09:08:00.000-05:00

In the past one of the items at the API committee meetings has been the review of inquiries sent in by those of you who had questions concerning some aspect of the API-650, API-653, or API-620 codes. There have been some changes going on that has prevented this from happening or has reduced which inquiries would be reviewed at the committee meeting. After the last meeting I thought this had been worked out so that at this meeting inquiries would once again be considered. In fact the schedule has a time set aside for this. I had submitted several inquires last time and resubmitted them this time anticipating that I would have answers at this meeting. After requesting verification that my inquiries had been received by the right person, I received a reply that said API has changed their requirements once again on how inquiries are to be handled. I am not sure what all this entails but hope to have it explained at the meeting in November. What I do know is that some of the committees accepted this new process and are following it. However, the committee that would be reviewing the inquiries I submitted decided that instead of using the new process they simple would not review or answer inquiries. I do not now where this leaves us. We shall see.

Update on Addendum 1

2008-10-28T09:02:00.002-05:00

I have been trying to find out when API-650 11th Edition Addendum 1 was going to be released. I finally got an answer back. They now say it will be released in "November or December". The way it has been going I would say it will be December. It appears that they are trying to clean up some of the typo errors that exist as well as adding the changes. I think they had a lot more of the committee checking over what they were putting into the addendum. In the process they made a lot of corrections which meant it had to go back to the editors and be revised and rechecked. Hopefully there will be very few errors they will need to be corrected after it is released. As far as Addendum 2, they have not indicated any date. Just that it will be next year. We may have a better idea when we get to the API meeting in a few weeks. I will keep you posted.

API-650 11th Edition Addendum 1

2008-10-16T15:45:00.002-05:00

It has been a while since I posted. I will be trying to correct this in the future. First, there have been many questions concerning when Addendum 1 to the 11th Edition will be released. We are all still asking that question. I have asked API and am waiting for a reply. It might be November but we shall see. At the April meeting we were told that Addendum 2 would be released by the end of this year. Who knows, maybe Addendum 2 will be released before Addendum 1! I will be attending the API committee meetings in early November. By then we should have some type of answer.

I have submitted a series of inquires to API to try to get answered at this next meeting in November. After the meeting I will let you know what the results are of these inquires.

With regard to our software, ITSdesign, we have made several revisions to the program. An addition was made to allow you to enter additional wind moments and wind shears. We have added IPE, IPN, and HEA beam shapes to our SI database. We have also corrected some beam weight problems in the SI database. With regard to seismic designs, we have added a checkbox for entering "Peak Ground Acceleration" and values for "Q" to accomodate seismic areas not covered by ASCE7. Other minor corrections have also been done.

In my next post I will comment on some more of the changes that supposedly are coming in Addendum 1.

ITSdesign Additions

2008-08-30T18:13:00.002-05:00

We have just released an update to our ITSdesign API-650 and AWWA D-100 tank design software. In this release we have added the ability to specify a maximum allowable stress for shell plates that is less than what is specified by the code. We also added a link to the USGS website for obtaining the seismic values needed. The biggest addition is that we added the ability to use channels and wide flanges as center and intermediate columns. The column can be either a single beam or it can be a composite beam. Drop down menus allow you to select which beam sections you want to use. Corrosion allowances can also be applied to the beam sections. In addition we have corrected a couple of printing errors. We are constantly working to add to and make corrections to our software.

New Revisions to ITSdesign

2008-07-28T11:45:00.002-05:00

I have just posted a revision to ITSdesign. In this revision I added new data entries for shell and roof appurtenance weights in the corroded condition. This allows you to have a different weight for the new and corroded condition. I also added a new data entry for the percentage of the roof appurtenances that is transferred to the shell. For column supported roofs this allows you to specify how much of the weight is transferred to the shell for resistance to overturning. The appurtenace weights have also been added to the resistance to uplift when internal pressure is present. For wind girder required section modulus I have added the 'm' factor to account for increased loading per 5.9.7.1. I also added to check whether Appendix F calculations need to performed based on the weight of the roof and appurtenances as compared to the uplift due to internal pressure.

For those who are using ITSdesign, see the Revision block for other minor revisions to ITSdesign. We continue to strive to make ITSdesign as accurate and complete as possible. Suggestions for additions and corrections are always welcome.

API-650 Appendix J Material

2008-07-17T20:17:00.002-05:00

I have been debating about what to do with the material requirements for an Appendix J tank. What is specified in J.2 is that the material must meet the requirements of Section 4. This would mean that if you use A36 material in a shop built tank with a design metal temperature of -10 degrees F, you would have to impact test the material. What is strange to me is that if I built that same tank to Appendix A the material does not have to be impact tested per A.2. I plan on presenting the question to the API committee at the next meeting. In the meantime, I have added a checkbox to the design page of our software where you can select to use the material limitations of Appendix A. Each user will have to determine whether their customer will allow them to use the material as specified in Appendix A instead of the requirements of Section 4.

We have made some additional modifications and corrections to ITSdesign. Be sure to read the revision notes to see what we have done.

API-650, 11th Edition, Addendum 1

2008-07-17T08:23:00.002-05:00

I am continuing to review Addendum 1 to the 11th Edition of API-650. Here are some comments on what I have found so far.

1) There are many slight modifications in the values used for SI units. Places that used to specify 12.5 mm now use 13 mm. In the table for 5.1.5.9(e), they have revised the angle size slightly. In 5.5.1 they changed 172 MPa to be 171 MPa. In 5.6.3.1 they changed the limit for using the 1-foot method for shell design to 61 m. Revised the angle size in 5.9.3.1 and 5.9.3.2.
2) In 5.2.1 (loadings) they revised the external pressures so that tanks with internal floating roofs with circulation vents do not require a minimum external pressure.
3) In 5.2.1 they also added loading requirements for internal floating roofs.
4) In 5.6.1.3 they added additional rules when using a lower allowable stress material in the upper courses. You now can do an elastic analysis or the lower course must be no thinner than the required thickness for product design or hydrotest design of the upper course.
5) They have revised some of the tables for manway neck thicknesses, nozzle reinforcement, cover plate thicknesses, and flush cleanouts.
6) For intermediate wind girders, the shell course thickness is now to be based on the thinnest shell course which may not be the top shell course.
7) An expanded design for frangible roofs has been added.
8) 5.10.2.9 now states that the purchaser can specify that lateral loads be imposed on the roof supporting columns.
9) 5.10.3.2 has been revised to reduce the minimum thickness for roof support columns from 0.25" to 0.236".
10) 5.10.4.4 has been revised to provide calculations for the maximum spacing of the roof rafters. It also set the maximum spacing at 84". These limits apply to both inner and outer rafters.
11) 5.11.2 has been revised to add a limit on the value of wL for the wind condition. It also now specifies that tb is in the corroded condition. A calculation of the minimum annular ring width for wind has been added.

This covers most of the changes I see in the design section (Section 5). Next time I will give you information on the changes to the various appendices and which new appendices have been added.

To keep our software, ITSdesign, current, we are already working on the revisions to incorporated these changes into ITSdesign.

API-650 11th Edition Addendum 1

2008-07-07T15:18:00.003-05:00

Can you believe it! I have finally received a proof copy of Addendum 1 to the 11th Edition of API-650! Yes, Addendum 1 will be finally released in the next 4 to 6 weeks. I will be working my way through this addendum to see what changes have been made. It looks like Appendix E has been corrected. Also, duplex stainless, aluminum, and mixed material appendices have been added. There is a change in Appendix V on how loadings are calculated combined for wind and vacuum. It appears there are some minimum thicknesses that are changing slightly. There is also a change in the determination of the maximum spacing of rafters (both inner and outer). The calculations for anchor bolts has changed as well. Appendix F has revised formulas for calculating the internal pressure. Appendix S has specific requirements for the use of "seamed" stainless steel.

This is just a quick overview of what I see in my first glance through the addendum. I will be posting more on the specific changes as I begin a more complete reading of the addendum. Be sure to come back for more information.

3 Bay Rafters

2008-05-20T09:13:00.003-05:00

I would like to annouce that we just released an update to ITSdesign that includes 3-bay rafter systems. This applies to API-650 and AWWA D-100 tanks. In this update we also corrected some calculations related to SI units including the change from using 0.785 as the factor for pressure in the anchorage calculations to using 785. This change may possibly appear in Addendum 1 when it is released (still no proof copy yet). We continue to expand the capabilities of ITSdesign in both US and SI units. Also, we continue to verify that it is up to the latest edition of the code. If you have not tried ITSdesign, you can download a trial copy at www.innovativetanksolution.com. You will find the program easy to use. If you do have questions, we are here to answer them. You can contact us at its@innovativetanksolution.com or by calling 651-480-0258.

API-650 Table 5-21

2008-05-16T08:12:00.002-05:00

I received a reply on my concern with the formulas in Table 5-21a for SI units and it is agreed that the formula is wrong when pressure is included in the calculations. They are now trying to determine what is the easiest and fastest way to make the corrections. In my program, ITSdesign, I will use the factor of 785 instead of 0.785 for the pressure. This revision will be included in the release I will do this weekend. There is a possibility this change could make it into Addendum 1 but I kind of doubt it. Maybe they will release an errata sometime soon after Addendum 1 is released. I have not seen the proof copy of Addendum 1 so am still wondering when it will end up being released. I will keep you informed on this.

API-650 Table 5-21 Uplift Loads for Anchorage

2008-05-15T09:45:00.003-05:00

After returning from the API committee meeting I began looking at revising ITSdesign to conform to the changes approved to Table 5-21, Uplift Loads for anchorage. I had reviewed the changes proposed and agree with the changes being made. However, as I began rewriting the program and checking the output, it appears to me that the factor in Table 5-21a (SI units) is wrong. In looking back at even the 10th Edition, Addendum 3, it has a value of 0.785 for the factor when working with pressure. However, the pressure is in kPa while the result is to be in N. When checking the units we are off by a factor of 1000. I have written a note to the person who handled the agenda item and requested a claification. I will let you know what his response is once I receive it. In the meantime, I am revising ITSdesign for the SI units to use a factor of 785 instead of 0.785. I will also be incorporating the changes as approved by the committee for the agenda item.

API meeting in New Orleans

2008-04-28T11:06:00.002-05:00

I attended the API meetings in New Orleans. There were some things addressed. Here is a brief summary.

1) Addendum 1 to the 11th Edition of API-650 should be released by the end of May. The proof copy we received was incomplete and they have not resent the complete proof copy yet. I will let you know when that occurs.
2) All of the agenda items approved at last falls meeting and this spring meeting are supposed to be coming out in addendums by the end of the year.
3) Table 5-21 was revised to conform to the combination loadings. This should be in Addendum 2.
4) Self-supporting roof calculations are changing that would use the strength of the material. This could reduce the compression ring area when highe strength materials are used. This should be in Addendum 2.
5) Clarification of the API-620 references in F.7 are still being worked on.
6) Shell nozzles larger than 48" is still being worked on.
7) Several minor items were approved and several are being reworked or reballoted.

Inquiries that had been submitted for review were not considered due to some timing problems. Hopefully this will be resolved by the next meeting.

Not much came out of this meeting. I will keep you informed as to when Addendum 1 is ready to release.

API meeting

2008-04-14T21:47:00.002-05:00

I am currently at the API meeting in New Orleans. The day has been very disappointing. I found out that Addendum 1 for API-650 now will probably not be released until at least June. In fact the draft I have is incomplete. When released it should include new appendices X and SC. We shall see.

The other disappointment was that they did not review design or fabrication inquiries. They were scheduled to take place. However, it seems that all those inquiries we sent to API staff never made it to the heads of the committees in time to be sent out to the other committee members to review. Therefore, none of them are being reviewed at this meeting.

We will see if tomorrow is any more productive. We will continue to add to and update ITSdesign. We will also keep you updated on what is happening here at the committee meetings.

API-650 11th Edition Addendum 1

2008-03-30T21:23:00.002-05:00

I have started reviewing a copy of the final draft of API-650 11th Edition Addendum 1. I have not seen a lot of major changes. I do see that they have corrected Appendix E and it appears that it is the same as Addendum 4 of the the 10th Edition including the errata. Other areas I will be reviewing as to the affect on designs are the definition of Pe, the definition of material thicknes in 5.3.5, changes to manholes and nozzles, changes in frangible roof designs, and a change in maximum rafter spacing. I will be reviewing these and will comment more after Addendum 1 is released by API.

I will also be attending the API committee meetings in New Orleans the middle of April. I will let you know if any important information comes out of that meeting.

We are continually updating, correcting, and adding to ITSdesign, our API-650 and AWWA D-100 design software. Changes to ITSdesign are automatically received by our users the next time they start ITSdesign on their computer. All updates are automatically downloaded from our internet site.

API-650 App. R

2008-03-05T16:15:00.002-06:00

In API-650 11th Edition Appendix R, there is a factor of 0.40Pe (external pressure) or 0.40Pi (internal pressure) added to various loading conditions. This same factor is used when determining anchor bolt loads on anchored tanks due to wind or seismic. However, there is also a note that says that if the operating pressure divided by the design pressure is greater than 0.40, the purchaser should consider using a higher value than the 0.40. How many times do we see a operating pressure but no specified design pressure? Many times the purchaser only knows the pressure he wants for operating and specifies that as the design as well. If you just plug these values into the formulas given then you will be designing a tank for less than what the operating conditions will be. We probably do not want to increase the design pressure to 2 1/2 times the operating pressure if the purchaser has not specified this condition as this will greatly increase the thicknesses or cause a requirement for anchorage or stiffeners. However, care then needs to be taken to address these other conditions to make sure we are providing an adequate design. Towards this end, our ITSdesign software now incorporates a check for the ratio of the operating to the design pressure, flags this condition, and provides the option to increase the factor beyond the 0.40 value as needed.

Two span rafter system

2008-02-26T14:34:00.002-06:00

A new version of ITSdesign has just been released. The new update now includes two span rafter systems for both API-650 11th Edition and AWWA D-100-05. The design includes inner and outer rafters, intermediate girders, center column, center column base plate, intermediate columns, and intermediate column base plate. You can choose different material grades for the girders than for the rafters allowing higher strength material for girders. A new "Loadings" report has been included to show the loadings on the columns and shell.

Look for more additions coming soon.

Correction

2008-01-29T08:15:00.000-06:00

A correction to my previous post.

API-653 3rd Edition, Addendum 3 is currently under final review and will be released soon.

I apologize for the error.

ITSdesign Update

2008-01-28T20:32:00.000-06:00

We are just releasing an update to ITSdesign. A couple of corrections have been made and a couple of additions. One addition is that we now have an export to an Excel spreadsheet. We are seeking comments as to whether the format we have will satisfy the needs of the users. You can comment here or email me at its@innovativetanksolution.com. The other addition is adding tooltips to the entire program. If you place the cursor on an item you will get a note explaining the use of that particular item. Also, if it is yellowed, which indicates that an error has occured concerning that particular item, additional information will be displayed concerning the error. That way you do not need to click on the Code Errors tab to see the errors.

Other notes of interest:
API-620 11th Edition appears to be in final review and will be released soon
API-650 3rd Edition, Addendum 3, appears to be in final review and will be released soon
API-650 11th Edition, Addendum 1, has not been released for final review but is to be released soon and will be released shortly thereafter

We will be going to the API committe meetings in April and are getting ready to submit inquiries. If you have any inquiries you would like us to submit for you, contact us and we will see what we can do. Right now we are waiting to see what Addendum 1 changes are before we do the submission.

API-650 11th Edition now available

2008-01-09T09:10:00.000-06:00

As of January 1, 2008, the API-650 11th Edition is now in effect. To meet this requirement we have revised ITSdesign to be in conformance with the new 11th edition. The updated version of ITSdesign is now available from our website at www.innovativetanksolution.com. Those currently using the program will receive the updates the next time they open the program. In addition to updating to the 11th edition, we have also added the base plate designs for center columns to conform to paragraph 5.10.4.7.

We have not revised the seismic portion of ITSdesign as what is in the 11th edition is incorrect and will be corrected in the soon to be released Addendum 1. As soon as that is released, we will revise the seismic to meet the Addendum 1 corrections.

Yes, there is an addendum scheduled to be released for API-650. The last word I received is that it would be released sometime in January. I will keep you informed as to when this does occur.

API-650 11th Edition

2007-12-27T12:06:00.000-06:00

It has been too long since I posted information concerning changes about the 11th Edition of API-650. Here is the next part having to do with changes in Section 5, which is design. This used to be Section 3.

5.1.3.6.1 specifies that multipass welding is required for manual welding processes on fillet weld legs or groove depths greater than ¼”. For semi-automatic and automatic welding processes multipass welding is required for welds greater than 3/8”. This applies to bottom plate welds, roof plate welds, and shell-to-bottom welds for Groups I, II, III and IIIA materials.

5.1.3.7 specifies that all attachments to the tank exterior shall be completely seal welded (intermittent welding is not permitted) except as specified in 5.1.5.8 for wind girders.

5.1.3.8 says permanent backing strips are not permitted (unless approved by the purchaser) except as permitted in 5.1.5.5 and 5.1.5.6 which is for butt-welded bottom plates.

5.1.5.1.b specifies that the top surfaces of bottom welds shall be ground flush where they will contact the bottoms of the shell, insert plates, or reinforcing plates.

5.1.5.8.b requires all horizontal bottom-side joints of wind girders shall be seal-welded unless specified otherwise by the purchaser. (Previously seal welding of the underside was only required if specified by the purchaser.)

5.1.5.9.c adds tension rings and compression rings to top-angle sections that require butt-welds shall have complete penetration and fusion.

5.2.3.d adds localized loads resulting from such items as ladders, stairs, platforms, etc., shall be considered.

5.3.1.2 specifies that sliding friction resistance shall be verified for tanks subject to lateral wind loads or seismic loads.

5.3.2 provides how corrosion allowances are to be applied. (Many of these had been scattered throughout the code or not specifically defined.)

5.4.4 specifies that unless otherwise specified, tank bottoms requiring sloping shall have a minimum slope of 1:120 upwards toward center of tank.

5.4.5 adds requirements for foundation drip rings if specified by the purchaser.

5.5.3 requires that if the product height times the specific gravity of the product exceeds 75 feet, then you must perform an elastic analysis to determine the annular plate thickness.

5.6.1.1 note 4 says that for diameters from 10.5 feet to 50 feet, the minimum thickness of the lowest shell course only is increased to ¼”. (The question is does this apply to field erected tanks or was this a note related to Appendix J tanks??)

5.6.1.5 adds that isolated radial loads on the tank shell, such as those caused by heavy loads on platforms and elevated walkways between tanks, shall be distributed by rolled structural sections, plate ribs, or built up members.

5.8.5 has been added to address the limitations for roof venting. Normal and emergency vents shall prevent the internal pressure from exceeding the pressure calculated in F.4.1 with some other limitations as well. Screen sizes are specified as being ½” nominal opening.

5.8.10 specifies platform, walkway, and stairway requirements. They have added that unless declined on the data sheet, a roof edge landing or gaugers platform shall be provided at the top of all tanks.

5.10.4.7 provides requirements for column bases. A ¼” wear plate seal welded to the floor is required or you can provided a thickened bottom plate that also distributes the load. Guides for the column to allow vertical movement of at least 3” are required and cannot be welded to the tank bottom. Several possible methods are given in Figure 5-26.

I will posting more soon. Also we will be releasing a revision to ITSdesign which will bring it into compliance with the 11th edition.

API-650 Wind Design with I > 1 or Exposure D

2007-08-13T11:55:00.000-05:00

API-650 provides the formulas for designing a tank for wind. However, the formulas are all based on a importance factor (I) = 1.0 and an exposure = C. If your requirements are for exposure D or an importance factor greater than 1.0, you have to modify all of the calculations. For the wind loadings you need to calculate a new horizontal load and a new vertical load using ASCE-7. For this you have to determine values for Kz, Kzt, Kd, G, Cf, and GCp from ASCE-7. From these values you can then calculate your new loadings. You also have to calculate a new horizontal loading based on the base wind velocity. To this you have to add the internal drag pressure specified in 3.9.7.1 and compare that to the base value used in the calculations for maximum wind girder spacing as well as for sizing requirements for wind girders.

The effect on your wind calculations is greatly dependent upon the height of your tank. The API-650 formulas are based on Kz = 1.04. For a short tank with exposure C, Kz could be equal to 0.85 which will give a lower horizontal wind load depending upon the importance factor. The vertical uplift from wind might increase depending upon the tank height. If you have a higher tank or a tank with exposure D these values will increase and will probably result in higher loadings on the tank.

The effect on the wind girder requirements for a short tank probably will not change as you cannot use a factor less than 1. The values will change for taller tanks, tanks with higher importance factors, and tanks in exposure D.

Because there is becoming more of a requirement for importance factors greater than 1.0 and the possibility of clients requiring exposure D, we have just released our new version of ITSdesign to include calculations based on ASCE-7 for these conditions. If you enter either a importance factor greater than 1.0 or exposure D, ITSdesign will automatically provide the calculations based on ASCE-7 requirements.

API-650 11th Edition

2007-08-07T21:11:00.000-05:00

There are changes from the API-650, 10th edition to the 11th edition. I will be reviewing some of these changes over the next several postings. So here goes!

Added new paragraphs 1.1.4 and 1.1.5 and revised 1.1.6 and 1.1.18 to specify that Appendix L data sheets are mandatory unless waived by the purchaser, all tanks and appurtenances shall comply with the data sheet and attachments, field tanks shall be furnished completely erected, tested, and ready for service connections unless specified otherwise, and shop tanks shall be furnish tested and ready for installation.

Added Appendix W providing recommendations covering commercial and documentation issues.

Added section 1.3 to outline the responsibilities of the parties involved.

Added section 1.4 to specify documentation requirements.

References was moved to section 2 instead of being a part of section 1.

Added section 3 to provide definitions.

Material are now in section 4 and have the following changes:
1) Rimmed or capped steels are not permitted.
2) Cast iron for pressure parts or for attachment by welding to the tank is prohibited.
3) Cadmium-plated components shall not be used without the consent of the purchaser.
4) Added section 4.7 on bolting stating that (unless otherwise specified on the data sheet) flange bolting shall be A193-B7, anchors shall be threaded A36 round bar with heavy hex nuts and shall be galvanized, and all other bolting shall be A307 or A193, and A325 may be used for structural purposes only.
5) Added section 4.8 on welding electrodes.
6) Added section 4.9 stating gasket material is to be specified on the data sheet and shall not contain asbestos unless specified by the purchaser. Gaskets shall be made with integral centering or positioning device. No sealing compound, adhesive, or lubricant shall be used unless specifically allowed by the purchaser. Spare gaskets are not required unless specified on the data sheet.
7) Test gaskets must have comparable dimensions and compressibility characteristics as service gaskets. Descriptions of gaskets for temporary use only as test gaskets shall be submitted for purchaser’s approval.
8) The test gasket for joints that will not be disassembled after testing must be the specified service gasket.
9) Flange bolts and nuts used for testing are acceptable for use in the completed tank except for stainless steel bolting.

This takes us through section 4. Next time we will continue our look at the changes in the 11th edition.

AWWA D-100-05 is now in ITSdesign

2007-07-06T10:16:00.000-05:00

Finally! Yes, we are finally releasing our newest update to ITSdesign! It now includes AWWA D-100-05 designs in addition to API-650 Addendum 4 designs. The new release has shell designs per the standard and per Section 14, wind designs, seismic designs per Section 13, self-supporting cone and dome roofs, single span rafters and center columns, anchor bolts, and anchor chairs. Current users of ITSdesign will automatically receive the update. A trial copy of ITSdesign can be obtained by going to www.innovativetanksolution.com and clicking on ITSdesign download. We are continually expanding the capabilities of ITSdesign and look forward to your comments concerning what you would like to see added or changed. ITSdesign is a design program for designing steel tanks to the API-650 Addendum 4 code and now also the AWWA D-100-05 code.

Email notification

2007-06-07T19:40:00.000-05:00

How would you like to get an email notifying you when I have posted another blog? You can! Just look for the subscription sign up on my blog page. When you subscribe, you will receive an email the morning after I make a post. It will give you a brief idea on the topic posted. This way you will know when a post has been made without having to constantly check to determine if there is one.

API-650 meeting

2007-06-05T16:04:00.000-05:00

It has been too long since I did the first post. I need to catch you up on what is coming with regards to API-650.

An errata was issued in April following the committee meetings in Seattle. Most of the changes did not have an affect on our ITSdesign program as they were more notation in nature.
1) The changes to Equations E-18 and E-21 did affect the program and have been changed. They actually reduce the seismic load.
2) We had changed Equation E-20 and E.6.2.2.3 (second equation and fourth equation) quite a while ago.
3) There still seems to be a problem with what they have shown for Equation E-23a and E-23b. It would seem that E-23a should have a factor of 196 not 1.96 and that E-23b should either be 1.28 or 1.25 but not 1.96.
4) Equation E.6.2.2.3 (third equation) should still have a factor of 83 not 8 as shown.
5) Equation E.7.2 (second and fourth equations) where corrected to remove the I and replace it with 1.
6) There seems to be a problem with the equation changes in V.7.3.3, V.7.3.4, V.8.2.1.3 and V.8.2.1.4. For the first two equations, if the factor for the US units is correct then the factor for the SI units should be 19.0 and 13.4 respectively. The 13.4 factor corresponds to what is used elsewhere in the save appendix and elsewhere in the code. The latter two equations do not make any sense as they did not even show the original equation correctly to begin with. As such we have currently left all of these equations as in the orginal Addendum 4.
7) The change in V.8.2.3 from 32tb to 16tb was in our original program change as we did not feel this was correct to begin with.
8) The change in the example equation of V.10.2 corresponds to what we have built into our program except that according to the definition of fc, it does not have to be less than 15000 psi.

The 11th Edition of API-650 is about to be released. I just received an email stating that the final review was completed today and it will be released (I assume to the printers). I would expect to see something in the next few weeks. At the meeting they indicated it would be released sometime in June and it appears that is going to happen. Once that is released we will see what changes they have made. Along with that I would expect an addendum to the 11th Edition to be coming out by the end of the year.

There were many interesting things discussed at the meeting in Seattle. Some where just for discussion and some are going to be coming sometime in the near (??) future. A few of the items being discussed are:
1) They are looking at adding 201 and 201LN material to Appendix S.
2) They are working on an appendix that would add duplex stainless to the code.
3) They are workng on an appendix that would add mixed materials (carbon steel, duplex stainless, and austenitic stainless). You would then be able to use these materials in various combinations in one tank. You could then have a duplex stainless bottom and first ring and the rest carbon steel or other combinations.
4) There are modifications to the safety factors for Appendix V being worked on.
5) The problem of using narrow plates shop welded to make shell plates is being addressed along with the extent and location of x-rays required.
6) Shell nozzles larger than 48" are being worked on.

It will be interesting to see how much of this is included in the 11th Edition or the first addendum when it comes out. I will keep you posted.

API-650 Addendum 4

2007-03-13T21:16:00.000-05:00

When API issued Addendum 4 to the API-650 Storage Tank specification many aspects of the code were affected. The wind and seismic designs were change to try to bring them more into line with ASCE7, a new section for vacuum design was added, and a new section specifying load criteria was added. Sometimes the changes are difficult to interpret and time consuming to perform.

ITSdesign is a software program developed by Innovative Tank Solutions, LLC, to address these problems and to assist designers in meeting the requirements of the Addendum 4 of API-650. We are continuing to develop this program to meet the requirements of the code and the needs of the users of this design software.

Our goal is to help our users better understand what the code is requiring and how ITSdesign helps them meet those requirements. We want our users to better understand how to work with ITSdesign. To this end we are going to be posting questions and answers about both the API-650 code and the ITSdesign software.

We are working on adding AWWA D100-05 designs to ITSdesign and will be keeping you posted as to the progress on that part of the software. We will also be dealing with questions concerning this design code as there have been many changes to it as well.