Transcript Pipingsolutions, Inc - Piping Stress Analysis & Consulting

Pipingsolutions, Inc
Pipe Stress Analysis –
Where Do I Start?
This is a step-by-step logic guideline for the data collection effort that should
occur prior to beginning to model a piping system for a stress analysis:
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Training Presentation
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Step 1: What do you wish to achieve?
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
k.
Calculate stresses in a piping system and compare them with code
allowables
Evaluate the loads on rotating equipment nozzles and casing
Evaluate the loads on nozzles on heat exchangers, pressure vessels
or tanks
Evaluate the loads on structural anchors
Evaluate the loads on pipe supports
Evaluate piping movements from thermal expansion or contraction
Evaluate the effects of wind loads on the piping system and attached
equipment
Evaluate the effects earthquake loads on the piping system and
attached equipment
Evaluate the effects of wave loads on the piping system and attached
equipment
Evaluate the effects of soil resistance to piping system movements
and stresses
Evaluate the effects of changes in temperature, pressure and weight
on flanged connections to identify possible flange leakages
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Steps 2, 3, & 4:
2. Which Piping Code will govern the
design of the piping system?
3. Collect all plan and elevation drawings
4. Obtain or construct an isometric drawing
– align North arrows
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Step 5: Collect the Necessary Physical Properties
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
k.
l.
m.
n.
o.
Nominal Pipe Diameter
Pipe Schedule / Wall Thickness
Corrosion Allowance
Specific Gravity of contents
Insulation Material or Density & Thickness
Piping Material or density, modulus of elasticity & coefficient of expansion
Operating Temp, Design Temp, Upset Condition Temp & Base or Ambient Temp
Operating Pressure, Design Pressure & Upset Condition Pressure
Flange Rating & Type
Valve Rating & Type
Elbow and/or Bend Radius or Bend Radius Ratio and Fitting Thickness
Reducer Length, Inlet & Outlet Diameters, Schedule or Wall Thick, Concentric or
Eccentric
Branch Connection Type
Expansion Joint Properties – Translation & Rotational Spring Constants, Length of
Bellows, Length of Tie Rods, Pressure Thrust Area
Structural Member Specifications – AISC designation for standard shapes &
dimensional info for non-standard shapes
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Step 6: For All Anchors, Collect the Following
Data:
a.
b.
c.
d.
Location
Stiffness or Flexibility
Movements mostly from thermal growth
Origin of thermal growth in Anchor
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Step 7: For all restraints collect the following data:
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
k.
l.
Location of each restraint
Translational Restraints - the axis of action & 1 directional or double acting
Limit Stops – the axis of action, the plus and minus gaps and stiffness when limit is
encountered
Imposed Movements - the axis of action & the amount of the movement (+/-).
Imposed Forces - the axis of action, the amount of the force (+/-) & spring constant,
if applicable
Dampers – the axis of action
Frictional Resistance to Movement - the plane on which the friction occurs, the static
and dynamic coefficient of friction
Existing Spring Hangers - the location, the installed load, the operating load, the
spring constant & the minimum and maximum loads of the spring hanger . It is also
helpful to know if the spring hanger supports from above or below the pipe
New Spring Hangers - the location, the number of spring hangers in that location,
the percentage load variation allowed and whether a hanger or support is most
desired
Rotational Restraints – the location and the axis about which rotation is to be
resisted
Imposed Rotations - the location, the number of degrees of rotation and the
direction of rotation
Imposed Moments – the location, the amount of moment and the direction of action
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Step 8: Special Effects
Special Effects such as Cold Spring:
– Cut Short - the location, the axes of
application, the amount of cold spring &
whether Cut Short or Cut Long
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Step 9: Special Loading Conditions
a.
b.
c.
d.
e.
Wind Loading – the piping segments where wind is to be
applied, the orientation of the wind vector, wind speed or
pressure per unit length and shape factor
Wave Loading – the piping segments where wave loading is to
be applied, the orientation of the loading vector, the wave
loading pressure per unit length and shape factor
Uniform Loads such as Snow and Ice – the piping segments
on which the loads are to be applied, the amount of the
loading per unit length and the load orientation with regards to
W,Y & Z
Seismic Loads – the method to be used to simulate the
seismic event (RSA or percentage of gravity) and the
magnitude of the seismic event
Soil Interaction – the piping segments on which soil restraints
are to be applied, the soil spring constants or the soil
properties
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Steps 10 & 11:
10. Orient the Global (X,Y,Z) Axis System on
the Isometric Drawing – Y is always Up
11. Now, assign Node Numbers to the piping
isometric drawing in accordance with the
guidelines set forth in the next
presentation
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Pipe Stress Analysis –
Where Do I Start?
For more details please contact:
6219 Brittmoore Road
Houston, Texas 77041-5114 U.S.A.
Voice: 713-849-3366
Fax:
713-849-3806
e-mail: [email protected]
©PipingSolutions, Inc.
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