15 Replies Latest reply on Sep 23, 2017 3:32 AM by Scott Friday

    How to cut saddle joint end of nozzle pipe for weld grind?

    Scott Friday

      I have a pipe that comes out of a head perpendicular to the header, a basic T configuration. I am trying to model the weld for that saddle joint. It requires that the end of the pipe have a 45 degree bevel all the way around, starting with the inside face of the pipe and opening toward the outside face of the pipe. I have tried all manner of swept cuts and just can't seem to figure it out. I can't figure out how I might do it with a loft cut. I am still pretty new to Soldiworks. I have attached the 14" pipe part file. In the lower right corner is a sketch of a line showing the cut profile. I realize it is not a closed profile, I am just trying to show the angle/shape of the cut. After the cut, I don't want any material left below the line anywhere around the saddle joint. So the cut needs to follow the inside edge of the pipe.

       

      Once I get the cut, how do I model the actual weld? It is supposed to have the 45 bevel through the pipe wall and then a 3/8 fillet from the outside of the pipe wall down to the O.D. of the header pipe. I assume it would have to be some kind of lofted boss?

        • Re: How to cut saddle joint end of nozzle pipe for weld grind?
          Todd Blacksher

          Scott,

          I am on 2017 SP3.0, so I saved this as a parasolid file so that you will be able to open it.

          Not sure if this is what you are after, but you can do a swept cut using the edge of the pipe.

          Start a 3dSketch, select the edge, convert entities, close the sketch, and you will be able to use this as the path for the swept cut.

          Close out the profile on your sketch, and then you can use it for the profile of the swept cut.

          It may or may not be what you need, but this is an option.

          todd

          • Re: How to cut saddle joint end of nozzle pipe for weld grind?
            Matt Peneguy

            This is the kind of thing I'd just handle in the drawing by pointing to the joint:

            As far as creating the bodies.  I'd use weldments and just hide show the bodies in the drawing.  Let SWX do the work for you:

            Now if you want to show the individual top body create a projected view to the right or left, then select, "Select Bodies":

            and choose the top body with the saddle and it'll be isolated:

            Then detail away... Good luck.

            • Re: How to cut saddle joint end of nozzle pipe for weld grind?
              Glenn Schroeder

              I have to agree with Matt Peneguy.  If you have to model the bevels for welds you need a new welder.  One that knows what he (or she) is doing.  (He wasn't that blunt but I think that's what he was getting at.)

                • Re: How to cut saddle joint end of nozzle pipe for weld grind?
                  Scott Friday

                  Thanks for the feedback folks.

                   

                  Sorry, I did not think to explain why I was trying to do this. We do provide weld symbols for our drawings. The fabricators know what they need to do, so that is not the problem. We have been doing 2D drawings forever (30+ years) and have only recently needed to switched to SW from Acad. Ideally, we want to eventually get to the point where we can do finite element analysis on our designs. I may be off track, but when I was taking a SW class a while back and asked about that, I was told that I would have to actually model the welds. So far, this saddle joint weld is the only one I can't figure out how to create. The others are pretty straight forward. Was I told incorrectly about needing to model the welds to do FEA? Also, I might eventually want to print 3D miniatures of our designs and it would be nice for the welds to show.

                   

                  Todd's parasolid file above is pretty close, but I can see that the cut surface does not stay at a 45 deg angle to the inside wall of the pipe as it sweeps down toward the bottom of the saddle. Maybe my OCD is kicking in here...

                   

                  I have attached the full design, which it not huge, so you can see the other welds and where I am trying to put this one. I need it where the 14" and 10" pipes come out of the 18" pipe.

                • Re: How to cut saddle joint end of nozzle pipe for weld grind?
                  Dennis Bacon

                  Those swept cuts will drive you crazy Scott. I did try it using a guide and it looked good but if I split the part up I was getting different angles. As much as 4° off of 45°. Also tried it with a solid swept cut but was unsuccessful. I think you may have the right idea with a loft cut but I also can't figure that one out.. What I did is make a ruled surface with Tapered to Vector then used that to cut the part. When I split the part up I had a consistent 45° all around. I know this is supposed to be a grind operation but it's nice to have the model like you want it. When it comes to modeling the weld beads It hurts my head to think about it. So I'm with the others on that.

                   

                  Edit:... Here is you Tee with a sweep for a weld. There may be a way to do this with the Fillet Bead feature. I will look into that.

                  Probably could alter the look in the rear by using a spline on surface for one of the guides.

                    • Re: How to cut saddle joint end of nozzle pipe for weld grind?
                      Scott Friday

                      I'm still not 100% sure how you did that, but I have downloaded your changes and am going through the steps trying to make sense of it. You basically did what I was thinking, defining two guide curves to control where the edges of the weld touch the two pipes, but I just don't know SW well enough yet to figure out how to create those curves. Thanks for the effort!

                      • Re: How to cut saddle joint end of nozzle pipe for weld grind?
                        Scott Friday

                        Dennis,

                         

                        So I was able to figure out what you did and how to replicate it. Thanks for that.

                         

                        I then tried to do the same thing on the 10" stub out that has a blind endplate on it. Since that pipe is not cut like the 14" pipe, I had no edge to use for the "Ruled Surface" step. The temporary axis of the 10" pipe worked for that. You used the inside wall of the pipe. I had fits with the "Cut with Surface" step and kept getting a bad geometry error. After some Googling, I found someone that mentioned the need to "Knit Surface" because of gaps. So I knit the cutting surface with the inside wall of the pipe. That took a few tries and having to play with the gap range settings before it worked. So I was able to create the 45 degree cut on the end of the pipe.

                         

                        The "Offset Surface", "Extend Surface", and "Split Line" all worked fine. I've never worked with surfaces so this has been VERY educational for me! My problem comes with creating the sketch to use for the sweep. Again, unlike the 14" pipe, the 10" is not cut so there are no edges I can use for anchoring the sketch points. I tried doing a section view using the plane that cuts the 10" pipe in half. I am able to anchor the inside corner with a coincident relation where the pipe comes to a point at the surface of the 18" run pipe. But I cannot create any of the other coincident relations like you have on your sketch. I am unable to select the sloped edge of the 45 deg cut or the surface edge of the pipe at the top of the cut. I can eyeball it and have an undefined sketch, but when I try to do the sweep, I get a rebuild error that mentions a problem with Profile #2... Interestingly, the preview shows that it would look exactly like I would expect if it worked!

                         

                        This is NOT a huge priority. It is simply part of my learning experience, so it is not something that I HAVE to figure out. But wrestling with stuff like this has been teaching me a lot about how to do things in SW. So I do appreciate the help everyone has offered.

                      • Re: How to cut saddle joint end of nozzle pipe for weld grind?
                        Dennis Bacon

                        Ok Scott,,, If you have any interest in this let me know. I used a sweep to fill the bevel then a fillet bead on that. The fillet bead does add mass to this (not just an annotation type of thing), so I expect it would be there for 3d printing.

                        • Re: How to cut saddle joint end of nozzle pipe for weld grind?
                          Todd Blacksher

                          Scott,

                          Couple of quick things:

                          There is a lot of good stuff here, and I agree that you really shouldn't need to worry about the bevel on the tube.

                          (Unless you will be cutting this on a tubing laser, and you are able to cut the cope at whatever angle you specify.)

                          Most places would probably cut & grind the angle.

                           

                          With that said, I have attached a file that should work for a tubing laser.

                          The approach that I usually take is to create it as a surface and then "thicken" to get the tube - this will make the "cut edge" normal.

                          This also makes it easier to do a swept cut.

                          Throw in a little swept cut "option tweaking", and you should end up with a pretty nice part.

                          As I said before, unless you really need to show this level of detail, look into weldments and some of the other options that people have suggested.

                          With regard to FEA for welds - using the Simulation package, it is possible to "define" a weld without actually modeling the weld bead.

                          hope this helps (and doesn't add more confusion),

                          todd

                            • Re: How to cut saddle joint end of nozzle pipe for weld grind?
                              Scott Friday

                              Todd, thanks for the clarification about defining welds versus modeling them. As I mentioned, this was an experiment for me to see if I could model them based on the assumption that I might need to. However, if the simulation doesn't require them to be modeled, then I really have no need to do so. I've not yet even dipped my toes into running the FEA stuff as we don't yet have the software. It is seriously expensive and we are a small company (three people). Just getting three legit copies of SW was a big hit for us.

                                • Re: How to cut saddle joint end of nozzle pipe for weld grind?
                                  Matt Peneguy

                                  Scott Friday,

                                  You may actually have the software you need, depending on what you need to model.  SWX Simulation Xpress comes with SWX Standard and above.  It handles most of our needs, but you may need flow simulation or another advanced package based on that need.

                                  Regardless, if you want to start on that path, see the post by Keith Frankie  over at Simple example-shaft, hand calculation about the "21 FEM Examples".  I started watching the videos and ordered that book.

                                    • Re: How to cut saddle joint end of nozzle pipe for weld grind?
                                      Scott Friday

                                      Thanks Matt. I will definitely check into that. We will just need to evaluate hardware based on internal pressure (like pressure vessels), distributed loads (like point contact around a circle trying to shear out a lip), point loads (like bolts attached to face of plate), and bending loads like on a bolted flange. We don't do anything with flow stuff.

                                        • Re: How to cut saddle joint end of nozzle pipe for weld grind?
                                          Elmar Klammer

                                          Hello Scott,

                                           

                                          Here is a sample Tee joint with a equal leg fillet weld modeled. I only did the fillet weld and deleted some stuff out. I also attached a weldolet model from the web. It is a good learning tool for principle joint modeling (all credits go to the original designer). On a different note. The weld between the flat plate and the thru pipe is unrealistic modeling. Ask yourself how would you do that.

                                          Hint: You would weld the plate and the pipe first and machine the step down & grooves later. Your joint would not look like that in this case.

                                           

                                            • Re: How to cut saddle joint end of nozzle pipe for weld grind?
                                              Scott Friday

                                              Howdy Elmar,

                                               

                                              Thanks for the files.

                                               

                                              From talking with the fab guys in the various shops that build from our designs, here is what I've been told. Keep in mind, I rarely try tell them how to weld stuff unless the final end customer has specific requirements they impose. I usually just say, here is the final geometry we need, make it happen. They do their magic and the end user is usually thrilled.

                                               

                                              The flat plate would have the step down machined across its surface on both ends of the clamp (but not that little curved divot). The pipe would then be cut to match that profile. The circular end plate would have the flat cut across the bottom and a hole already burned into it prior to welding, but that hole would be small enough that it would not interfere with the weld running across the flat/circular plate joint. In this case, the final bore dimension is around 16.20, so the smaller hole would likely have been around 13-14". I don't know what order they weld the plate, pipe, and end plate together (not sure that it matters). Anyway, once the parts are joined, they come back and open up that small bore to the final size, cutting right through flat/circular plate weld in the process. So what you see in my model is what is left of that weld after the machining. Machining the bore is also what makes the small curved divot which keeps the flat plate from hitting the nuts on the side of the flange on which it is will be closing. Here's shot of it that shows the weld profile and I put a line in there to show there the bore was prior to machining the grooves.

                                               

                                              Flat Plate to Circular Endplate Weld Profile.jpg

                                               

                                              Cutting through welds like that is not something we like to do. However, there are very rare cases, like this one, where we can get away with it because the internal pressure of the clamp is only around 10 psig, so stresses are VERY low in the plate where the weld has been completely removed.

                                               

                                              Knowing the guys in the shop, I suspect there would likely be a continuous bead of weld at the step down near the bolt hole. I just didn't try modeling it ;-)

                                    • Re: How to cut saddle joint end of nozzle pipe for weld grind?
                                      Scott Friday

                                      Success!

                                       

                                      Using the same method Dennis outlined for me earlier, I figured out how to do the 10" stubout. The key is the relations used in the sketch before the sweep. SW wanted to infer coincident relations for the three points of the triangular profile I wanted to sweep. I deleted ALL constraints. I then picked the each vertex of the triangle and used the pierce constraint to attach each point to the path along which it would be sweeping. Once I did that, it worked perfect.

                                       

                                       

                                      14 in pipe cut for nozzle with all welds.jpg