Instrumented Functions (IPL's)

Instrumented Systems – Instrumented Functions

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Welcome to this Application Explainer video, part of our Instrumented Systems topic range.

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In this video, we’ll cover the subject of instrumented functions within SLM.

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Instrumented functions refer to the independent protection layers identified in LOPA that are instrumented in design.

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SLM has six different instrumented IPL types.

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They are alarms, basic process control system, BCS, fire and gas functions, higher integrity protective systems or HIPS interlocks, and safety instrumented functions sifts.

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The following information will be covered in this training chapter.

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One will be instrumented function types and structures.

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Chapter 2 will be creating functions and their structures.

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Chapter 3 will be equipment and P and ID associations to functions and iOS.

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Chapter 4 will be adding function set points and Chapter 5 will be adding auxiliary functions.

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In Chapter 1, we’ll be covering general function structures, structure of an interlock and fire and gas function, structure of a SIF and HIPS, structure of an alarm, and structure of a BPCS.

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The input structure is made-up of input groups, input voting groups, and inputs.

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Input groups and input voting groups are objects or layers in which voting can be applied, while the inputs are the components of the function.

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Similarly, the output structure is made-up of output groups and output voting groups, which are voting layers and outputs which are components of the function.

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In the diagram, the input and output portion are joined together by a logic solver.

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Logic solvers are included in the design and are direct children to all function types.

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Now that we have shown the general structure of our functions, let’s look at what is incorporated into the structure for each of the instrumented function types.

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Both interlocks and fire and gas functions have the entire input structure and output structure, which include the two layers of voting and the input and output components along with the logic solver.

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The structure of SIFS and HIPS are the same, incorporating the entire input and output structure and the logic solver.

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The main difference is a third layer of voting, which is the voting between the input groups and the voting between the output groups.

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Additionally, logic solver voting can be applied.

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The structure for an alarm includes a logic solver and the entire input structure and shows the alarm tag in the diagram.

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Once again, voting can be applied to the voting layers.

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A BPCS is unique in that it can incorporate the logic solver or DCS, and the entire input and output structures, including the voting layers.

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However, if voting does not apply, inputs and outputs can be added directly as children of the BPCS, as shown in this diagram.

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In Chapter 2, we’ll be covering creating a function, creating a logic solver, creating the IO structure with edit tools, creating the IO structure with the instrumented inputs and outputs tabs, and applying voting to the input and output structures.

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Rules for linking objects To successfully link objects, the following rules apply.

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The object can only be linked to the parent object, the object cannot be linked to the categories or other non parent objects, and the objects must be linked to a parent object in the same site.

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To create a function in SLM, navigate to the Instrumented Systems module.

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Functions can be added on two different levels.

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On thesis using edit tools, the possible functions are interlocks, SIF, hips, and fire and guess.

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On the unit level, we’ve edit tools, the possible functions are alarm, BPCS, fire and guess, interlocks, SIF, and hips.

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In this example, we’ll add an interlock.

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To add the interlock, type in the interlock ID and then press Save or Save and Edit to navigate to the newly created interlock.

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Once the function has been added, the structure for that function can be created.

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As explained in SLM 101 videos.

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Each object can be added to the parent object using Edit Tools.

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We’ll start building out the structure by adding a logic solver.

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To add a logic solver to the function, click on Edit Tools and add Logic Solver.

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Enter in the Logic solver ID and then click Save or Save in the Edit.

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Remember, if the logic solver is already created, it can be linked by selecting the link option.

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After selecting the logic solver in the drop down, click on Save to add the logic solver and that can be seen in the diagram at the top.

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Next we’ll look at adding the input and output structures, which can be done in two different ways, Edit Tools and the Instrument Input and Instrument Output tabs.

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Remember that the input structure is made-up of the input group, input voting group, and input objects, each being a child of the previous objects.

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The output structure is similar with output group, output voting group, and Output objects.

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To begin the process of adding the input structure with Edit Tools, click on Edit Tools and add an input group for any voting layer.

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SLM has a setting in the system module which allows the choice between auto generated IDs or providing the ID at the time of the object creation.

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The setting shown in this video will be how to add with auto generated IDs.

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So in adding the input group, just press save and edit and that will navigate you to the newly created input group with the auto generated ID.

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To add the input voting group, click on Edit Tools, Add Input Voting group and once again save and edit because it’s a voting layer to add the auto generated ID.

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As you can see in the structure they have in the object tree the input group and the input voting group.

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To add the input, navigate to Edit Tools, Add input, and this time, because it’s not a voting layer, type in the tag for the input.

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Save and edit to navigate to that input.

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Now that we’ve added the input structure, that structure can be seen in the diagram at the top here.

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The next method for adding the input or output structure will be using the Instrument Inputs or Instrument Output tabs.

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We’ll build out the output structure with the Instrument Outputs tab.

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The difference in this method is that instrument outputs allow you to see the entire structure all at once.

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To start the process, click on the Add Output Group button and this time just press save.

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Here’s your output group.

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Scroll down to the output voting group to add it.

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Next, once again, just click on Save.

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And now we have our auto generated IDs and then we can add our output.

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Because this is an output tag, we’ll type in the tag here and remember, you can clone if the tag already exists by selecting the tag and choose Action Clone Selected object.

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Now that’s save.

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We’ve now created a clone of what is previously created.

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In this view, the entire structure can be edited all at once.

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Once the structure is created, users may wish to change the voting object IDs to a name or relevant to the organization.

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This is accomplished by clicking in each field and saving individually, or using the edit button at the top to open multiple fields for editing all at once.

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Once all edits have been made, scroll to the top and click Save.

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Navigating to the first tab, Interlock Functional Requirements will allow you to see the structure for that interlock.

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Now we have the input structure on the left, the logic solver in the middle, and the output structure on the right.

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Voting can be applied on any voting layer.

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This can be done by clicking on any voting object or the instrument inputs or instrument output tabs.

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Voting can be applied on any voting layer.

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The N value is a read only field based on the number of children selected participating in the voting.

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The M value is the number of children that have to work or vote to trip for that group, which together allow for the function to bring the process to a safe state.

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SLM architecture uses voting for success.

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To apply voting, first enter into edit mode and select the number of children participating in the voting, the N value.

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Scroll to your right and enter in the number of children that have to work or vote the trip the M value.

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The voting on the output group is the voting between output group Voting groups.

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Scroll down to apply the voting between our outputs or the output voting group level by selecting the nvalue once again, scrolling over and entering in the M value.

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Once all voting fields have been filled in, press Save and now the voting in this example of one out of 1 can be seen.

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Both the structure and voting for the function can be seen on the 1st tab for that function in the diagram shell.

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The voting between inputs and voting between outputs can also be seen in the Cause and Effects matrix.

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In Chapter 3, we’ll be covering associating equipment to functions and associating PN IDs to iOS.

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Each instrumented function can be associated with the equipment it’s protecting.

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To associate the two, find the Equipment field on the 1st tab for that function.

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Once in Edit mode for the field, select Desired Equipment and click Save.

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Now the equipment that that function is protecting can be seen.

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In order to see all functions that are protecting that equipment, navigate to the equipment in the object tree and Scroll down to the associated Barriers table.

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The next object to be associated are the Input and Output objects with the PN ID.

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Navigate to the Input or Output object, Scroll down to the PN ID reference field, select the PN ID that the output or input can be found on, and click Save.

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Now that the association exists between the two, click on the PN ID, which will navigate you to the global module and the PN ID objects on that module.

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Click on the document and click on the PN ID specifically associated with that document.

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These PN IDs can also be seen on your Cause and effects matrix when the input or output object is selected to be shown.

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In Chapter 4, we’ll be covering setting up a setpoint and adding setpoints to a function.

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All instrumented functions covered in this video can have setpoints added to the function.

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To view or add setpoints to the function, navigate to the Performance tab for that function.

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Setpoints can only be added when an input object exists for that function.

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Once in edit mode, enter in the sensor setpoint value if needed, entering the Engineering Unit setpoint value.

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Select the setpoint type and the trip settings.

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Enter in a setpoint tolerance and a time delay and the basis for that setpoint and any notes that you would like to add.

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Then click on Save for SIFS.

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The setpoint time delay will add to the SIF response time.

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The setpoint information for each input will appear on the Cause and Effects matrix.

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For the input shown in Chapter 5, we’ll be covering adding auxiliary functions and viewing auxiliary functions in the object tree and in the Cause and Effects matrix.

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Auxiliary functions can be seen on the Aux Functions tab of the SIF object.

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They show the secondary actions that occur when a SIF has been activated, but do not contribute to the voting or sealed calculations of a SIF.

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This view displays the auxiliary function tag, description and interlock or timing information.

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To add an auxiliary function to a SIF, click on the Add Auxiliary Function button, enter the tag and any additional information, and save the changes.

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Once the auxiliary function has been added, it can be viewed under the object tree for the SIF and in the cause and effect matrices where its effects can be specified.

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See the video on cause and effect matrices to learn more.