# Is there any good way in prepomax to select the inner surface of a long tube for loading? **URL:** \ **Category:** General Questions\ **Created:** [July 13, 2022, 5:00am UTC](https://prepomax.discourse.group/t/is-there-any-good-way-in-prepomax-to-select-the-inner-surface-of-a-long-tube-for-loading/292 "2022-07-13T05:00:11Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![xupeiwust](https://avatars.discourse-cdn.com/v4/letter/x/f0a364/32.png) [@xupeiwust](https://prepomax.discourse.group/u/xupeiwust)\ **Post date:** [July 13, 2022, 5:00am UTC](https://prepomax.discourse.group/t/is-there-any-good-way-in-prepomax-to-select-the-inner-surface-of-a-long-tube-for-loading/292/1 "2022-07-13T05:00:11Z")
Is there any good way in prepomax to select the inner surface of a long tube for loading? ---
**Author:** ![lucas\_bueno](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/lucas_bueno/32/1168_2.png) [@lucas\_bueno](https://prepomax.discourse.group/u/lucas_bueno)\ **Post date:** [July 13, 2022, 2:27pm UTC](https://prepomax.discourse.group/t/is-there-any-good-way-in-prepomax-to-select-the-inner-surface-of-a-long-tube-for-loading/292/2 "2022-07-13T14:27:06Z")
Can you please share an image of the tube? I usually create a surface or set before applying the load/boundary condition if it is hard to reach a specific location. For this, I use the cut tool or surface angle to select the regions I need. ---
**Author:** ![SergioP1975](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/sergiop1975/32/37_2.png) [@SergioP1975](https://prepomax.discourse.group/u/SergioP1975)\ **Post date:** [July 13, 2022, 8:21pm UTC](https://prepomax.discourse.group/t/is-there-any-good-way-in-prepomax-to-select-the-inner-surface-of-a-long-tube-for-loading/292/3 "2022-07-13T20:21:52Z")
Hi @xupeiwust , just create first a Surface set and choose the Set selection mode to Surface Angle, increase the angle if is not enough, but if the faces are tangent there will be needed only one clic to select all the element surfaces of the internal side of a tube. ---
**Author:** ![xupeiwust](https://avatars.discourse-cdn.com/v4/letter/x/f0a364/32.png) [@xupeiwust](https://prepomax.discourse.group/u/xupeiwust)\ **Post date:** [July 14, 2022, 1:56pm UTC](https://prepomax.discourse.group/t/is-there-any-good-way-in-prepomax-to-select-the-inner-surface-of-a-long-tube-for-loading/292/4 "2022-07-14T13:56:42Z")
![1](https://global.discourse-cdn.com/free1/uploads/prepomax/original/1X/a5f114db5356e61dc4e04e698f9740bfd1bee261.png) The shape of the tube is more complicated, it is a bellows, if it is other software, such as ansys, hypermesh, I can remove the outer surface, and then the remaining surface is the inner surface, but prepomax seems to be unable to do this operation, in fact, the software selection methods are diverse , is the key for the software to solve engineering problems. Many engineering problems are very simple, but the model is very complex and the loading position is very complicated, so the preprocessor needs to have a good selection method and a variety of loading methods. ---
**Author:** ![xupeiwust](https://avatars.discourse-cdn.com/v4/letter/x/f0a364/32.png) [@xupeiwust](https://prepomax.discourse.group/u/xupeiwust)\ **Post date:** [July 14, 2022, 1:57pm UTC](https://prepomax.discourse.group/t/is-there-any-good-way-in-prepomax-to-select-the-inner-surface-of-a-long-tube-for-loading/292/5 "2022-07-14T13:57:18Z")
Thanks for your suggestion, I will try to choose ---
**Author:** ![SergioP1975](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/sergiop1975/32/37_2.png) [@SergioP1975](https://prepomax.discourse.group/u/SergioP1975)\ **Post date:** [July 14, 2022, 6:03pm UTC](https://prepomax.discourse.group/t/is-there-any-good-way-in-prepomax-to-select-the-inner-surface-of-a-long-tube-for-loading/292/6 "2022-07-14T18:03:52Z")
Increase the Surface Angle to 45-50°. Or maybe more, but it should work. You could create separate parts, even if they are the same one phisically, just to be able to hide/show the hoses and bellows separately. ---
**Author:** ![Matej](https://avatars.discourse-cdn.com/v4/letter/m/a698b9/32.png) [@Matej](https://prepomax.discourse.group/u/Matej)\ **Post date:** [July 15, 2022, 7:23am UTC](https://prepomax.discourse.group/t/is-there-any-good-way-in-prepomax-to-select-the-inner-surface-of-a-long-tube-for-loading/292/7 "2022-07-15T07:23:30Z")
If you need to select the entire inner surface, that should not be a problem since it is a tangential muli-face surface. You select the selection surface by angle. Otherwise, the outer surface cannot be removed, and there is no possibility of selecting “deeper” surfaces at the position of the mouse click. But you could create a section view to see the internals of the tube at the desired location. ---
**Author:** ![xupeiwust](https://avatars.discourse-cdn.com/v4/letter/x/f0a364/32.png) [@xupeiwust](https://prepomax.discourse.group/u/xupeiwust)\ **Post date:** [July 16, 2022, 6:21am UTC](https://prepomax.discourse.group/t/is-there-any-good-way-in-prepomax-to-select-the-inner-surface-of-a-long-tube-for-loading/292/8 "2022-07-16T06:21:45Z")
I found a good way to select the meshes that are not needed on the surface, and then invert the selection ---
**Author:** ![Matej](https://avatars.discourse-cdn.com/v4/letter/m/a698b9/32.png) [@Matej](https://prepomax.discourse.group/u/Matej)\ **Post date:** [July 19, 2022, 10:14am UTC](https://prepomax.discourse.group/t/is-there-any-good-way-in-prepomax-to-select-the-inner-surface-of-a-long-tube-for-loading/292/9 "2022-07-19T10:14:34Z")
Maybe be careful that inversion works for all mesh entities (nodes or elements) and not only surface mesh entities. So if you select surface nodes of one face and then use inversion, the internal mesh nodes will also be selected.