Transcript Demystifying CAESAR II: What Problems is it Solving, Anyway?

What does CAESAR II do?
9/15/2010
Session overview




Taking the task from piping design to piping engineering.
What questions does CAESAR II answer?
A brief CAESAR II “design” sequence.
Should conclude within the hour.

Please use the Webinar dialog box to post your questions.
9/15/2010
Intergraph CADWorx & Analysis Solutions
2
Piping designer responsibilities

Designer locates equipment and then routes pipe between these positions using an
established “pipe” specification
–

Givens:
–
–
–

The piping system is a unique pressure containment.
Pipe size is based on pressure drop, flow rate
Pipe specification (e.g. wall thickness) is based on design pressure & temperature
Material based on service requirements
Designer has established rules for basic layout
–
–
–
–
9/15/2010
Hydraulic issues
Spans between supports (deadweight sag)
System stability
Access / clearance
Intergraph CADWorx & Analysis Solutions
3
So what’s left for the piping engineer?

Many systems require analysis to evaluate strain
–
Sources of thermal growth


–
Other sources of strain



Support settlement
Support movement in marine piping
Strain  Load  Stress
–
–


Pipe
Equipment connections (vessels and equipment)
Evaluate pipe load as stress due to this strain
Evaluate load on equipment directly
Except for simple layouts, the system response due to this strain is difficult to estimate
Analysis yields a better estimate of pipe deflection, loads on pipe supports and equipment
connections, and stress in the piping; and not only for strain.
100 feet @ 170F
9/15/2010
Intergraph CADWorx & Analysis Solutions
4
Designer “handoff” to engineering

Many shops develop a “critical line list” to determine which piping layouts require additional
engineering evaluation

So, a move is made from “Design by Rule” to “Design by Analysis”

A sample
Line List”
from PROCESS
PIPING: The Complete Guide to ASME B31.3,
This is
where“Critical
CAESAR
II enters
the picture
by Charles Becht IV, ASME PRESS, New York, 2002
========================================
•
In the case of general piping systems; according to the following line size/flexibility
criteria:
Designtemperature
by Rule vs.
Design by Analysis:
• All DN 50 (NPS 2) and larger lines with a design differential temperature over 260°C
(500°F)
Design by Rule:
• All DN 100 (NPS 4) and larger lines with a design differential temperature exceeding
Minimum pressure thickness = (PD)/(2(SEW+PY))
205°C (400°F)
• All DN 200 (NPS 8) and larger lines with a design differential temperature exceeding
150°C (300°F)
Design
by Analysis:
• All DN 300 (NPS 12) and larger lines with a design differential temperature exceeding
Maximum stress due to pressure = Sh = (2/3)(yield stress)
90°C (200°F)
Stress
duelines
to pressure
= PD/2t
•
All DN 500 (NPS 20)
and larger
at any temperature
•
All DN 75 (NPS 3) Is
andPD/2t
larger <
lines
to rotating equipment
Shconnected
?
•
All DN 100 (NPS 4)Yes:
and larger
OK lines connected to air fin heat exchangers
•
All DN 150 (NPS 6) and larger lines connected to tankage
No: Redesign required
•
Double-wall piping with a design temperature differential between the inner and the outer
pipe greater than 20°C (40°F)
9/15/2010
Intergraph CADWorx & Analysis Solutions
5
Four typical interests in “pipe stress analysis”




Selecting and sizing supports
Checking pipe deflection under load
Verifying loads on connected equipment
Evaluating pipe stress

And not only for those strain-based loads…
–
–
–
–
–
–
9/15/2010
Deadweight
Pressure
Wind & wave
Earthquake
Hydraulic transients
Vibration
Intergraph CADWorx & Analysis Solutions
6
Creating a CAESAR II Model



Start with a stress isometric or similar concept (the analog)
Mark up the drawing for analysis
Create the piping input model (a digital representation of that analog)
90
110
80
100
120
10
50
20
9/15/2010
Intergraph CADWorx & Analysis Solutions
7
Analog to digital
Analog
9/15/2010
Digital representation
Intergraph CADWorx & Analysis Solutions
8
CAESAR II Results
1.
2.
3.
4.
Hanger selection, restraint load
Pipe sag, horizontal deflection
Equipment check
Stress check
–
9/15/2010
A few examples will illustrate…
Intergraph CADWorx & Analysis Solutions
9
1. Size Support
Size this spring…
What is the load on
this steel?
…to minimize this pump load
9/15/2010
Intergraph CADWorx & Analysis Solutions
10
2. Check Deflection
How much does this elbow
move when the system
heats up?
9/15/2010
Intergraph CADWorx & Analysis Solutions
11
3. Evaluate Equipment Load
Is this compressor
overloaded?
Compressor
Thermal
Growth
Anchor
9/15/2010
Intergraph CADWorx & Analysis Solutions
12
4. Evaluate Pipe Stress
This stub in connection is
overstressed and will fail
by fatigue over time.
9/15/2010
Intergraph CADWorx & Analysis Solutions
13
Analyze and review TURBO
9/15/2010
Intergraph CADWorx & Analysis Solutions
14
Document Results
9/15/2010
Intergraph CADWorx & Analysis Solutions
15
Conclusion
9/15/2010
Intergraph CADWorx & Analysis Solutions
16