5.-La investigación sesgada: “Vivir de la alarma social”:
4. El tratamiento periodístico de la violencia escolar
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P&ID Lesson One - Video Five
CADWorx P&ID - Lesson One Video Five
1. In this video, we're going to add some valves. But first we want to adjust this drawing a little bit. Let's say that the managers came in and said, "All right, we want to have this line coming into this vessel closer to the top." So we need to move this line coming into our drawing from the left.
Type: Move <Enter>.
Select the line and the off-page link arrow.
Press <Enter>.
Pick a point on a grid line near it.
Move the mouse up to the grid line that is one down from the seam of the vessel and
Click.
2. Now we'll adjust the second line (the line leaving the top of the first vessel and going over to the second vessel).
Click Modify (from the pull-down menus).
If you don't see the pull down menus you can type: Menubar
<Enter>, then type 1 <Enter>.
Click Stretch.
Click two points to make a crossing window (right to left) and select the portion of the line you want to stretch.
Press <Enter>.
Click a base point on a grid dot near the line.
Move the mouse so the line is stretched like you want it and Click (it should enter the second vessel one grid unit down from the seam).
3. Zoom in around the left set of pumps.
If we take a look at a finished version of this drawing-- I have one already done, we can see that we have a swing check valve and a gate valve on the pump discharge line. In the suction line we're going to have a gate valve and a reducer.
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Copyright© 2014 All Rights Reserved CAD Training Technologies, LLC
P&ID Lesson One - Video Five
4. I'll do this set of valves on the first two pumps, and then I'll pause the video. Then you can do these valves and reducers on both sets of pumps. OK, so let me just show you this one first, and then you'll do it.
5. Now, I'll go back to our current drawing.
Click on Valves (if the panel is not displayed).
Click on the first valve symbol.
The system opens a dialog box showing the valves.
Select the Swing (this is a Swing Check valve).
Later, if we're running with a live database and a spec, we may want to be using some socket weld or flange type valves.
Since we're not working with a database, this symbol is fine.
Click OK.
Click a point on a grid dot, on the line above the pump nozzle.
You'll notice the system breaks the line, rotates the valve, and inserts it into the line. It has some nice automation here. Later, if the valve gets erased the system will mend the gap in the line back automatically.
This is another good example of why we want to use snap.
Because if you draw this without snap, and you put the valve over here, and you're just off a little bit, it won't rotate it and gap that line for you. So that's another reason why you must draw P&IDs using Snap.
The next valve we'll put is going to be a gate valve.
6. Click the first valve symbol again.
The system opens the valve dialog box.
Click Gate.
Click OK.
Click a point on the discharge line (on a grid dot) above the check valve.
Using grid dots to position these gives us good spacing.
P&ID Lesson One - Video Five
7. Repeat for the other discharge line.
8. Now we'll do the suction line.
Click the first Valve symbol again.
Click Gate.
Click OK.
Click a point on a grid dot (on the suction line).
Click on the Concentric Reducer symbol.
Click OK.
Click a point on a grid dot.
Drag the mouse to the left and Click.
The system prompts to "Select objects to assign the current reduction size to," It's asking you to pick the things that are downstream for this - that are smaller.
Click on the line leaving the small side of the reducer.
Press <Enter>.
When I first placed a reducer on my system, the reducer came in bigger than what I've shown here. If that happens in your case, just go ahead and put it on in for now. There's actually a way to fix that. If you need to resize yours, you can click on the Menu Symbols button. If you click that, and you click reducers, you can go click Concentric Reducer and Edit Item. Set the Side 1 size and the Scale to 3 (mine was originally set to 6). So if you encounter what I did and it's too big, well, you can fix it right there.
9. Repeat this for the other set of pumps.
All right, we have our values and our reducers done now around these pumps. This is a common geometry. It's typical to see a check valve and a gate valve above a pump discharge nozzle like this. The check valve keeps the fluid from backing up when the pumps are turned off, and they won't lose their prime.
10. Zoom Extents.
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Copyright© 2014 All Rights Reserved CAD Training Technologies, LLC
P&ID Lesson One - Video Five
What we're going to do now is put in a control station on the line leaving the vessel in the upper right area of the drawing.
Here's an illustration of how it will look.
We'll have a control valve with reducers and gate valves on either side. There will also be a bypass line.
The reason for that is (for those of you just getting started in P&IDs) these control valves need maintenance on occasion and the gate valves can be shut, and the globe valve on the bypass line can be opened. When the two gate valves are closed, the control valve is isolated and it can be worked on.
So this is a common geometry that you see.
11. Zoom into the upper right area of your drawing.
Click on the first Control Valve symbol.
You see we have a lot of variety of valve symbols that we can use in P&ID. Also CADWorx allows users to bring in their own custom symbols quite easily. This will be covered in future courses.
Click OK.
Click a point on a grid dot to place the valve.
12. Click Reducer - Concentric (from the Valves panel of the ribbon).
Click OK.
Pick a point on the left side of the control valve (on a grid dot).
The system prompts to select objects that are smaller-- that you want to assign the reduced size to.
Click on the line between the reducer and the control valve, and
Click on the control valve.
Press <Enter>.
P&ID Lesson One - Video Five Note: If you're zoomed in close and you try to place a valve, the system may not break out the line for you. This can happen if the line width is larger than the pick box, or aperture, on the cross hairs. So if you have trouble with that kind of operation, just zoom out a little bit and it should work.
13. Repeat the steps and place another reducer on the right of the control valve.
14. Click Gate (from the Valves section of the ribbon).
Click OK.
Place a Gate Valve on either side (put it centered on a grid dot).
15. Click Major Secondary (from the Process Lines panel of the ribbon).
Draw the bypass line as shown.
Place a Globe Valve in the bypass line as shown.
Note: A globe valve is used in bypass lines because the flow can be adjusted (not so with a gate valve).
16. Repeat these steps and draw another control station as shown.
Note: CADWorx P&ID does have the ability to copy something like this and make it an assembly. However, when you bring the assembly in, it must be "reconnected" into the line. In this example it's just as easy to draw them yourself.
All right, great! We're making good progress and moving right along. You can see how easy this system is to use. Mainly, it's just drawing using Snap and Ortho, which makes it easy to get everything lined up.
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P&ID Lesson One - Video Six