Hello out there! Anyone still with me? It's been a long time since I've had the time to post. Anyone who has seen my posts on Twitter or Linked In or on the Autodesk
® Discussion Forums knows that I am heavy into using Inventor's Tube & Pipe module. You may have also seen that I make no secret of my belief that this module is long overdue for a major facelift. It's a good system, but it is also responsible for more than a few of the grey hairs on my head!
I thought I'd put forth a few of my ideas for how this could be improved, based on my real world pipe design experience. This entire post will be my own opinions and thoughts, backed up with some snazzy pictures, and if I can figure it out, maybe a video or two. So... let's dive right in!
Changing or resizing fittings on existing Pipe Runs. Inventor Tube & Pipe works very well with few issues when you are designing a pipe run that is made up of a length of pipe with fittings placed inline along it, allowing spaces between the fittings. An example of an easy pipe run:
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| Example of smooth pipe route. |
In this example, the elbows have all been determined by the route and were placed when the route was populated. They will not move or change their orientation unless I edit the route and change the direction that way. The fittings that have been placed inline may be rotated in any way I choose, since the axis of rotation is the center line of the route.
Sometimes, however, the pipe runs I need to deal with do not have these nice long spaces between fittings populated by a pipe spool piece. In many of our designs I am dealing with a pipe run where the fittings are placed face to face with other fittings, with no intervening pipe length. The axis of rotation for any given fitting, now becomes the connection point on either end of the fitting. The more connection points, the more potential rotational axes. Example:
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| Face to Face Pipe Run |
In this example, the pipe segments you see are actually flanged pipe segments that we created, since a lot of our piping is plastic lined steel piping, and each spool piece is hand made to a specific length. Rather than place each one as a fitting, we wanted the flexibility to change the lengths on the fly as the design is progressing. I created a base spool as a pipe conduit in Inventor and placed it into several Tube & Pipe Styles. This will be covered in greater detail in another post I am formulating right now... look for that in a week or so. Anyway, notice that the majority of the fittings have no intervening pipe segments. Here is where the "fun" begins.
Pipe fittings that have been placed using fitting to fitting connections, rather than being placed inline on a route, have an annoying habit of wanting to change their orientation when they are modified in any way. If you attempt to change the size or replace the fitting with another similar fitting, (let's use the elbow on the left in the image above for this discussion) the new fitting tries to come in at a different rotation than the fitting being replaced. If this fitting is connected on both ends, this will cause a general "replace fitting error" message to pop up. If you are new to the program you might have no idea what the error means, or what the problem is. Breaking the connection on one end only allows the change to be executed, but the results may be... interesting at the least. The best solution, (and I say this sarcastically since this is no solution in my mind, but rather a workaround) is to break the fitting connections on both ends of the fitting. Then attempt the fitting change again. With this workaround the fitting should replace or resize fine and stay in place. (but wait, there's more).
Now that the fitting replace or resize has been done, it has to be reconnected to the rest of the assembly using the "Connect Fittings" command. Looking back to the image above, (remember it was the elbow on the left we used in this example), let's assume that we reconnect the elbow to the tee fitting in the middle. The fittings will connect with no problem, but to our surprise the elbow has rotated up 90°.
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| Fitting Rotated After Reconnecting |
Now we have to supplement the Connect Fittings command with Edit Fitting Orientation to rotate it 90° back down to it's beginning orientation. Now we have to connect it back to the pipeline. Using the Connect Fittings command again to select the elbow and the pipe segment.... Tube & Pipe creates a Pipe Route loop to connect between the fitting and the previous pipe segment!
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| Pipe Route Looped Onto Itself. |
So, after a few more taps of the Undo button, we have to actually delete the pipe segment and route a new segment starting from the elbow out to whatever length we need. Once that's in place we can use Connect Fittings to connect the new segment to the next fitting in the line, and finally... after all of these steps, we have successfully changed the size of one fitting in our pipe run. Now we can proceed to change any other fittings that need to be replaced or resized.
This to me is a huge waste of time for any designer, and therefore money. My proposed solution is hard to define since it depends on what the root cause of these issues is. But it seems that there are obstacles to the freedom and flexibility that a designer needs to be able to make changes to a design as a project unfolds. The fix may be in question, but the desired result is not. Fitting to fitting design is a large part of a piping designer's real world experience. The ability to quickly change, resize or otherwise modify these fittings in place, without causing rework to the rest of the pipe run or any other pipe runs attached to it, is a must have in my opinion. Design criteria change fast, the designer needs the ability to change a model as fast in order to keep up.
Changing Pipe Sizes in a Pipe Run.For a brief and ill advised period a few years back, my company switched to Pro Engineer for their Pro Piping module. There is little I can say good about Pro Piping, in my humble opinion. But there is one (and only one) thing it did better than Inventor's Tube & Pipe. Pro Piping had the ability to change pipe sizes WITHIN a single route, automatically. Let me break it down a little.
Fittings in Pro Piping were authored very similarly to those in Inventor. They didn't call it authoring, but I cannot recall what they did call it. (The bad memories are fading) The main difference was that instead of defining an insertion work point and axis for each connection, the user defined a coordinate system, making sure that the "Z" axis was facing in the direction of the connection. These User Coordinate Systems were then given a Size parameter. When routing pipe, the user selected a spec which was similar to Inventor's Tube & Pipe Styles, with one major difference. The spec did not have any size associated with it, it called out the material and allowed fittings. The size was determined by the size parameter on the fittings themselves. As long as the fittings and pipe which were allowed by the spec existed in the size currently being routed, the route would populate. Example: If you began a route at a previously placed Pipe Flange, which had a 2" parameter on the open port, the route would assume 2" as the nominal size. Any fittings placed in the line would assume 2" as well. If a reducer type fitting was placed inline, which had a 1" port on the other end, the pipe route and any existing fittings downstream of the reducer (as long as they existed) would automatically switch to 1" as determined by the size parameter on the reducer. if the program ran into a situation where a fitting or pipe to be reduced did not exist in the fittings allowed by the spec, the program would prompt the user as such and ask for a substitute to override the spec.
In Inventor, the same situation has two possible solutions. One is to route the 2" pipe up to the assumed location of the reducer and stop. The reducer fitting would be placed manually and connected to the end of the 2" route, and a new route created for the 1" pipe downstream. The other method is to route the entire pipeline as 2", place the reducer, and then manually change size on all pipe and fittings downstream. The problem with method 2, is that nay changes made later will revert the pipe segments downstream of the reducer back to the 2" specified in the Tube & Pipe Style, necessitating that the user change them manually again. As in the previous section, this does not allow for the flexibility needed by designers in the real world as things can change rather quickly.
I'm going to end this now and call this part 1, so that it does not get too long and bore you all to tears. I have more ideas and I'll work on compiling those into a part 2 soon. In the meantime....
Enjoy!
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