Tank Equipment
- 09 Aug 2024
- 4 Minutes to read
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Tank Equipment
- Updated on 09 Aug 2024
- 4 Minutes to read
- Contributors
- Print
- DarkLight
- PDF
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Tank Equipment differs a bit from other Equipment.
When defining Tank Equipment:
- A Compliance Code, e.g. API or DEP, must be selected in the Equipment details. Note: This affects the Load Case calculations.
You can select a Compliance code when creating tank Equipment. - Go to the Equipment’s Specs section and enter the specification. The table below highlights the required specs per Load Case.
Load Case Calculations
The Load Case 2 and 3 calculations can be accessed from the Equipment Details Page.
Tank Load Case 2 and Tank Load Case 3 can be accessed from the header in the Equipment Details screen.Load Case Calculations for Welded tanks can be summarized as follows:
Load Case 1 | Load Case 2 | Load Case 3 | |
|---|---|---|---|
Description | Shell calculated wall thickness | Buckling Calculation (wind) | Roof Pressure (on the Shell) |
Objective | Calculate the RL based on corrosion | Calculate the number of Wind Girders needed for the Course and the RL | Calculate the impact on RL of Roof pressure on the tank Shell. |
General RBI Specs **General Component Data *EQUIP SPECIFICATIONS **COMPONENT SPECS Other specifications might be required, depending on material, DM, Component | Compliance Code (e.g. DEP, API) Pitting (checked=yes) Joint Efficiency Factor** (if not specified, default derived from SRBI-SHELL JOINT TYPE*) Thickness as built** For Courses: Course Height** SRBI-DIAMETER* SPEC GRAVITY @ OP TEMP* DESIGN PRESS* For Roof and Floor: RENEWAL THICKNESS** | Compliance Code SRBI-MAX OPERATING TEMPERATURE* SRBI-WINDSPEED* SRBI-DESIGN VACUUM* AND the LCI Calculations | Course Height** (top Course) SRBI-DIAMETER* |
Output | RL (used for NID) Product Height** Minimum Allowable Wall Thickness** | Number of Girders required (optional) RL (for reference only) | RL (for reference only) |
Where to find it | RBI Analysis – Calculator Tab | Menu bar on Equipment Level | Menu bar on Equipment Level |
Notes | Recommended Approach | For first calculation, need to provide data for at least one inspection (with current wall thickness) | For a proper calculation of buckling, all Courses must be added. | If RL is lower than LC1, additional measures must be taken to assure integrity. |
Exceptions | LC1, LC2, and LC3 are not applicable to riveted Shells. | ||
Shell – Courses
To analyze the structural integrity of a Tank using the Load Case 2 and Load Case 3 calculations you will need to select the Governing Course of a tank.
The Courses are added as individual Shell Components to the Tank Equipment. Note: In the past these were added as Sub-Components, but this is no longer the case.
Each Shell Component represents one Course.
For each Course one Shell Component should be created under the Tank Equipment. Load Case 1
This is calculated during the RBI Assessment (Step 6). The results are shown on the Calculator tab. The above table highlights the required specs needed for LC1 calculations. You also need to provide data for at least one inspection, with Actual Wall Thickness. In addition to the RL, the Product Height and Minimum Allowable Wall Thickness are also calculated. These are shown on the Component Details Page.
For more information see: Tank Load Case 1 Calculations,
Load Case 2
The Load Case 2 Buckling Calculation is used to determine the RL for the tank based on the buckling load due to wind. The module will also determine the number of Wind Girders required for the tank. The above table highlights the required specs for Load Case 2.
- Go to the Component Details page.
- Click on Load Case 2 in the Equipment header.
- You can check the box for Extrapolated Corrosion Rates:
- Select the Corrosion Extrapolation Type ("Even" / "Top" / "Middle") for the pseudo Courses. Note: "Even" is the simplest, then BCR is used for all pseudo Course CRs.
- Specify the Base Corrosion Rate (BCR) and Ratio of (incr. CR / BCR) (R). Note: These are used to extrapolate the CR for the pseudo Courses.
- Select the Governing Course (GC). Note: The calculations use the Last Governing Date (LGD), which is the latest inspection date of the GC.
Select the governing course. - The number of Required Girders is shown.
- Add Girder(s) if required: Click on Girders and input the distance from the base of the tank. Note: Adding a Girder provides two more years of life for the tank for buckling.
To add Girders, click on one of the Girders links. - The Load Case 2 screen shows the results: Required Girders and Remnant Life.
Required Girders and RL is determined.You can find the detail calculations in Tank Load Case 2 Calculations.
Load Case 3
The Load Case 3 Roof Pressure is used to determine the RL of the tank for Roof loads.
- Prerequisites:
- A Roof Component must be created.
- Equipment Specifications and Component data, as highlighted in the table in Tank Equipment must be filled.
- At least one inspection with an Actual Wall Thickness must be recorded in the inspection history.
- The RBI assessment should be completed.
- Go to the Component Details Page.
- Click on Load Case 3 in the Equipment header.
- Enter the Superimposed Load (SL).
- Check Use Tank diameter look up for Load weight, to determine the Load weight data from a lookup table, else
- Enter the Load Weight data: Roof Plates (RP), Roof Framing (RF), and Top Angle (TA).
- Select the Governing Course (GC).
- The Load Case 3 screen shows the results: Axial Compression (AXC), Allowable Compression (ALC) and Remnant Life (RL).
LC3 results.You can find the detail calculations in Tank Load Case 3 Calculations.
Degradation Management for Tanks
In Tanks you will find addition guidance with regards to Degradation Management on Tanks and specifically the S-RBI analysis.
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