Large Diameter Pipe Design

[martin888888]

Quick question on the design and presentation for large piping. We have a 72" process pipe with a min slope of .25% needed for condensation and I&I drainage. When you have a 90 degree sweep in the pipe what is the "normal" way to design and present it on a set of plans. Do you design it and actaully show and profile through the sweep, or do you design and profile it through the PI as you do small diameter pipe? My feeling is that you do not show the sweep in the design. You will horizontally lay it out with the PI only and profile through the PI. The length through the sweep will be shown longer then it actualyl will be doing it this way however.

My experience with large pipe is limited so any imput is appreciated.

 

[racookpe1978]

From YOUR knowledge of the distances and lengths required, YOU are the only one who can tell what the impact of that 0.25% slope is on ordering lengths, setting pre-fab sections and spools, and shipping and installing the spools. In truth, it will probably not be important in a single building or room, but will be more critical the greater the horizontal distances. For equipment, for example, use a simple plan view unless the connctions are NOT square and plumb to the equipment nozzles.

BUT the section and elevation views MUST include the slope to ensure your supports and clearances and floor holes and wall penetrations are correct!

 

[dhengr]

Martin888888:
Why not show the center line length through the bend, plus beginning and ending tangent lengths, and do your calcs. on this basis? Then, at the beginning and ending joint locations show an invert elevation, or a difference in elevation btwn. the start joint and ending joint, and let the installer figure it out from there, as he assembles and welds the pipe? Then, when the beginning straight pipe is laid to the proper slope, that same slope should continue on through the bend, and continue on at the correct slope.