3 Bay Rafters

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

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

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.