Dummy and Base Supports

The vast majority of the incidents where a Dummy Support or a Base Support is required pipe-to-pipe extension method is the preferred.

In my many years in the design office, the pipe fabrication shop and the field, I found this to be true.

The only place where I used or saw Steel Shapes used was in Hydrogen service where you wanted to avoid the possibility of trace Hydrogen build-up that could result in an explosion.

Sidjain,
You wrote:
"(Our stress group restricted us for dummy length of 1.5' till pipe sizes 4")."

I think we should all question the logic behind some of the "Restrictions" that are placed on us by "Stress Engineers"

Example:
I am currently looking at a "Piping Span Chart" for Seamless Carbon Steel A53 Gr. B pipe.
It recommends no more than 23'-0" span with a deflection of 1" for 2" Sch 80 pipe..

Lets consider three lines.
We have pipe supports spaced at 20' 0'' apart.
Line #1 - 2" sch 80 straight pipe that spans from pipe support to pipe support with no change in direction or branches. No problem.

Line #2 - 2" sch 80 straight pipe line that spans from pipe support to pipe support with two branches near the mid point . No problem.

Line #3 - 2" Sch 80 pipe line must leave the pipe rack 5'-0" short of the next pipe support we are restricted from using a dummy support longer than 1'-6". Why can't I use a 2" dummy to complete the span?