Dimensioning Flange/Valve Pipe End Element

Dear Rich and Dave,

Common practice in denoting a distance (e.g., X) on piping isometrics takes measure from the "face" of a flange to a certain point of interest. Hardly by itself is a pipe flange dimensioned. In contrast to stress analysis using C2 program, one has to identify each and every flange individually on the input spreadsheet. The task could take three steps to complete:

(1) extract the flange length, Y, from the V/F database dialog,
(2) manually subtract the length Y from X on the piping isometric, and
(3) enter another node point and element with the X minus Y dimension to reach the point of interest.

If the flange instead is located at the end of an element, or a flanged spool piece, additional steps entail. Alas, in case of a skewed line C2 input can really become geometry-challenged.

My estimate is, modeling an in-plant busy piping system via Customary Unit in fractions can consume up to 40% of the modeling time doing all this. Concern over errors in adding or subtracting fractions can further result in repeated checking and rechecking the mathematics. After a little while one's concentration just gets sapped out, exhausted.

But it wouldn't seem all this travail is inevitable. Maybe C2 program can conjure up a simple routine to mitigate the stated hardship.

One ready option I can envision is adding a Check-box command, like "Hard Piping," to the Dimension Block. After one enters the length X and check the box, C2's F/V dialog--flange, rating, valve, etc.--will pop up, with another selection of FROM or TO or BOTH Check-box. Once properly picked, C2 then automatically breaks up the dimension X into two or three elements--one RIGID Element followed by a Pipe or vice verse, etc.--with new intermediate node point(s) similar to the elbow element currently in effect.

No, I am not alone troubled. A number of C2 seminar students have mentioned it to me, and suggested same.

Plese give this request an approxiate consideration. Thanks.

Your point is well taken. We have done some work in this area, but it was never finalized. I'll discuss this internally here for a quicker implementation.

Greetings Mr. Yin

I think your suggested program modification is a good one. In the mean time, I have two suggestions:

FIRST:
Instead of your steps 1, 2 & 3, you may save some time by doing this:
1) Use the V/F database to obtain the length/weight of the valve.
2) Having made note of the length & weight, turn off the Rigid specification and change the length of that element to the drawing dimension you refer to (flange + pipe).
2) Use the Break command and define the distance to the new node as the flange length. This provides the two elements of correct length.
3) Activate Rigid on the flange element and enter the weight.
I believe this is a more efficient approach that will save a bit of time and mental effort.

SECOND:
CADWorx/Pipe will let you build the model with less effort, and then create a CAESAR input file from it.
Of course this requires AutoCAD, CADWorx/Pipe and spending some time to get proficient with the program, but the time-saving may be worthwhile for you. This would also allow you to have less expensive CAD operators input the model and deliver the CAESAR input file to the stress analyst. Of course there are also the automatic stress isometric features among others that make this well worth considering.

If the user enters a pipe length and THEN clicks the V/F database, I could see C2 asking if you want the rigid element at the From Node or the To Node. The only issue, then, is the node numbering. C2 could ask for a number from the user to mark the end of the rigid element (at the From Node) or the start of the rigid element (at the To Node). If the pipe element was started with Alt+C, I could see C2 using the node increment to update the node sequence and keep things in order.

I think you guys are blowing this one out of proportion. I usually make a survey of the system that I'm about to model and make up a quick table of the valve and flange lengths and weights, typically rounding up to the nearest half inch to make the math easier to do.

From here, you can enter your dimensions spool length and break the spool using the flange dimension. If the flange is at the far end, I've learned that you break it as if it were at the close end. That solves for the unknown length, and you can then just switch those two dimensions.

As for modeling skewed runs of piping, that's also pretty easy. You typcially will have an overall length given along the run, in addition to the x and z components (assuming you model with y as up). I usually model along that straight length taking it along the x or z axis. After I've modeled the spool, I use the rotate command to swing it to the correct orientation and let Caesar figure out the x and z components for the valves, flanges, etc.

Hello all,

The way I typically model flanges next to valves is to code up to the flange face and use the Cadworx database for valves with flanges. I then change the dimension to that of just the valve. Essentially, I use the valve dimensions and valve+flange dimensions. This should be technically acceptable for lower pressure classes, but may not be OK for heavier flanges.

As for skewed lines, v.4.40 has the ability to put in the total length and direction cosines (press the "..." button next to DY). Put in the totals and then break the model.