presentation on piperack
TRANSCRIPT
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Pipe Rack Design28-August-2013
Prepared byEng. Abdussalam Al-Zahrani
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Introduction Pipe Racks typically support pipes, power cables
and instrument cable trays in petrochemical,chemical and power plants. Occasionally, piperacks may also support mechanical equipment.
Main pipe racks generally transfer materialbetween equipment and storage or utility areas.
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Cont.
Pipe rack is a structure made of steel, concrete or
both, i.e. hybrid structure that supporting :-Layer or layers of piping.
Electrical and instrument cable tray.
Mechanical Equipment if any.
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Concept of Design Structural components of the pipe rack must be capable
of resisting the axial loads, shears, moments, and torsion
produced by the load combinations given in Section 5.0
of SABP-M-007.
The pipe support framing system is designed as rigid
frame bents with fixed or pinned bases in the transversedirection and as braced frames in the longitudinal
direction.
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Steps for Design1. Geometry Modeling. (Dimensions, Section Properties, etc)
2. Loading. (Application of all possible loads)
3. Design Parameter (Kz, Ly, Lz, UNL, )
4. Analyzing & Design. (Check your modal, revise and change as needed)
5. Connection.By Spread Sheet or by StaadPro if Connection Module is available.
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Geometry The main components of the Pipe Rack are
Transversebeams
Verticalbracing
Longitudinalbeam
Columns
1
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LoadingTypes of load can be classified as follows:
Dead Load (Ds, De, Doand Dt)
Wind Load (W, Wp)
Earthquake Loads (Eo, and Ee)
Thermal Loads (T, Tp, Afand Ff)
Other Loads (O)
REF: SABP-M-007 Para.4 Page 7
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Loading Tree
Ty
pesofLoads
Dead
Self-Weight
Operation
Empty
TestLive
Wind
EarthquakeOperation
Empty
Thermal
Temperature
Anchor
Friction
Summarized from SABP-M-007 Para.4
2.1
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Piping Loads Operating dead load (Do): A uniformly distributed load
of 40 psf (1.9 kPa, kN/m2) for piping, product, and
insulation.
Empty dead load (De): 60% of the estimated piping
operating loads shall be used. (To check uplift with Wind or Earthquake)
Test Load Dt: The test load shall be defined as the gravity
load imposed by the liquid (normally water) used to
pressure test the piping.
2.2
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Piping Loads For any pipe larger than
12-inch (304-mm) nominal
diameter, a concentrated
load, including the weight
of piping, product, valves,
fittings, and insulation shall
be used in lieu of the 40
psf (1.9 kPa).This load shall
be uniformly distributed
over the pipe's associated
area.
SABP-M-007 Page 59
2.2
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Cable Tray Loads Operating dead load (Do): A uniformly distributed dead
load of 20 psf (1.0 kPa) for a single level of cable trays
and 40 psf (1.9 kPa) for a double level of cable trays.
*Comment: These values estimate the full (maximum) level of cables in the trays.
Empty dead load (De): For checking uplift and
components controlled by minimum loading, a reduced
level of cable tray load (i.e., the actual configuration)should be considered as the empty dead load.
Engineeringjudgment
2.3
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Wind load
F = qzG CfAe ASCE 7 (Eq. 6-25)
qz= Velocity pressure at height z above ground. G= Gust effect factor.
Cf= Net force coefficient.
Ae= Projected area normal to wind.
2.4
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Velocity Pressure qz
qz = 0.613 KzKztKdV I (N/m2
) Kz is the velocity pressure exposure coefficient per Sect.
6.5.6.6 & Table 6-3 of ASCE 7.
Kzt is the topographic factor per Sect. 6.5.7.2 of ASCE7.
Kzt is equal to 1.0 for Pipe Racks and Open Frame
Structures located in Saudi Aramco facilities.
Kd is the wind directionality factor per Sect. 6.5.4.4 and
Table 6-4 of ASCE 7. When used with load combinationsspecified in SAES-M-001, Kdis equal to 0.85 for Pipe Racks
and Open Frame Structures.
Wind Load2.4
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Wi d L d
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Wind Load
Table 3 of SABP-M-006 (Metric Units) provides values for qzatseveral heights for most Saudi Aramco sites. These values areto be used for Pipe Racks and Open Frame Structures.
SABP-M-006 Page 23
2.4
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Thermal Loads Ff = Friction Forces: 10% of total piping loads on
local supporting beam, 5% of total piping loadsacting on struts, braced, anchor frame, column andfoundation.
Af = Anchor Forces: Anchor and guide forces andlocations shall be obtained from the piping stressanalysis.
T = Temperature Force:
Design tem. = Highest Temp.Lowest Temp. + Metal Temp
*Highest & Lowest Mean Temp can be taken from SAES-A-112.*Metal Temp can be estimated at 20Co
2.5
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Calculation of the Earthquake Base Shear V
V = Csx W
Cs: The Earthquake Response Coefficient
W : The Effective Earthquake Weight.
Determination of Cs (Ref. ASCE 7-05_Clause 12.8)
Base Earthquake Response Coefficient
CS =SDS / ( R / I )
Maximum Earthquake Response Coefficient
CS =SD1 / { Tax ( R / I ) }
Minimum Earthquake Response Coefficient
Where:
CS shall not be less than 0.010 (Ref. ASCE 7-05_Eq.12.8-5)
CSshall not be less than 0.5 x S1/ ( R / I )
,when if S1 0.60g (Ref. ASCE 7-05_Eq.12.8-6)
CSshall not be taken less than 0.030 (Ref. ASCE 7-05_Eq.15.4-1)
CSshall not be less than 0.8 x S1/ ( R / I )
,when if S1 0.60g for non-building (Ref. ASCE 7-05_Eq.15.4-2)
Earthquake
2.6
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Load Combination (ASD)
Notes: a. Wind forces normally need not be considered in the longitudinal direction because friction
and anchor loads wil l normally govern.
b. Earthquake forces shall be applied in both transverse and longitudinal directions, but need notbe applied simultaneously.
c. 0.6Do is used as a good approximation of the empty pipe condition De.
d. Full Ds + Do value shall be used for the calculation of E in Load Comb. 4a.
e. Test Weight + Partial Wind normally is required only for local member design because hydrotest
is not normally done on all pipes simultaneously.
# Load Combination Multiplier Description
1 Ds + Do + Ff + T + Af 1.00 Operating Weight + Friction Force + Thermal Expansion + Anchor Force
2 Ds + Do + Af + (W or 0.7 Eo) 1.00 Operating Weight + Anchor + Wind or Earthquake3 Ds + Dec+ W 1.00 Empty Weight + Wind (Wind uplift case)
4a 0.9 Ds + 0.6 Do + 0.7 Eod 1.00 Operating Weight + Earthquake (Earthquake uplift case)
4b 0.9 (Ds + Dec) + 0.7 Ee 1.00 Empty Weight + Earthquake (Earthquake uplift case)
5 Ds + Dt + Wp 1.20 Test Load + Partial Winde
SABP-M-007 Page 15
Pipe Rack Allowable Stress Design (Service Loads)
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Load Combination (LRFD)
Notes: a. Wind forces normally need not be considered in the longitudinal direction because friction
and anchor loads wil l normally govern.
b. Earthquake forces shall be applied in both transverse and longitudinal directions, but need notbe applied simultaneously.
c. 0.6Do is used as a good approximation of the empty pipe condition De.
d. Full Ds + Do value shall be used for the calculation of E in Load Comb. 4a.
e. Test Weight + Partial Wind normally is required only for local member design because hydrotest
is not normally done on all pipes simultaneously.
# Load Combination Description
1 1.4 (Ds + Do + Ff + T + Af) Operating Weight + Friction Force + Thermal Expansion + Anchor Force
2 1.2 (Ds + Do + Af) + (1.6W or 1.0E) Operating Weight + Anchor + Wind or Earthquake
3 0.9 (Ds + De)+ 1.6 W Empty Weight + Wind (Wind uplift case)
4a 0.9 Ds + 0.6 Do + 1.0 Eod Operating Weight + Earthquake (Earthquake uplift case)
4b 0.9 (Ds + Dec) + 1.0 Ee Empty Weight + Earthquake (Earthquake uplift case)
5 1.4 (Ds + Dt) Test Weight
6 1.2 (Ds + Dt) + 1.6 Wp Test Load + Partial Wind
SABP-M-007 Page 16
Pipe Rack Loading Combinations and Load Factors - Strength Design)
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Analyses & DesignCheck STAAD Pro output for the following:
Unity Check: Ensure that unity checks for all
structural members are less than 1.0
Beam Deflection: Ensure that maximum beams
vertical deflection is less than L/240.Where L = span
length
Lateral Drift: Ensure that maximum lateral drift for
the pipe rack is less than H/100.
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PIPING
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Pipe rackpiping study
2D Sketch bypiping (x-section
of pipe rack)
Preliminary 3Dmodeling for piperack in study zone
Pipe rack layoutdevelopment
Preliminary stressanalysis of critical
lines
Support markupor anchor bayidentification
Piping loadinput tostructural
Pipe Rack Design Flow Chart
Routingchange or looprequirement in
layout
Is this layoutacceptable?
NO
PIPING
STRUCTURAL
PIPING
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Loading
Types
Wind
Spread Sheet
StaadPro
Seismic
Spread Sheet
StaadPro
Thermal
Spread Sheet
StaadPro
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References SAES-A-112
SABP-M-007
SABP-M-006
ASCE 7
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Thank You