Re: Re: ASME (or other) Piping Codes and Standards

On Aug 12, 2007, at 6:12 AM, bruce.r.raymond@fluor.com wrote:

> Being proficient on any CAD program does not make on a piping
> designer.

Too, too true. Designing is not making pictures, it is communicating instructions. Pencil and paper or computer monitor if your picture doesn't explain how something is to be built and how it's to be verified when it is built, all you have is a cartoon.

My favorite flag for identifying cartoons is dimensions referenced from centerlines. Centerline dimensions look so convenient, but in fact centerlines aren't actually recoverable on pipes or vessels which aren't truly, straight, round or uniform. Most shop people know this and the good ones can often make proper allowances, but it's so easy to use centerlines with CAD software without thinking how the vessel will ever be built or verified.

Same with 3D modeling. To make your cartoon into an actual design you need to know about materials specifications, stock sizes, product tolerancces and fabrication practices, especially welding and what happens when something is welded. Knowing about costs helps.

The biggest difference between a cartoon and an actual design document is organization and specificity. It's up to the designer, not the software to organize the presentation, so people can use it efficiently, and to make the instructions un-ambiguous. One of the real problems with CAD is that it's too easy to be disorganized and splatter details all around whether they're helpful or not, or to substitute eye-candy like perspective views for properly dimensioned and toleranced views.

Christopher Wright P.E. |"They couldn't hit an elephant at chrisw@skypoint.com | this distance" (last words of Gen.

.......................................| John Sedgwick, Spotsylvania