1 WELCOME TO INHOUSE TRAINING SESSION • DESIGN OF PIPERACK
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WELCOME TO INHOUSE TRAINING SESSION
• DESIGN OF PIPERACK
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CONTENTS
Introduction & Layout (DAY-1) Pipe Loading calculations for Piperack as per
Specifications Wind loading calculations as per IS:875-III Introduction to UBC-94 & its use for Calculation of
Loads for Piperack structure. Load Combinations for Design of Piperack Provisions of Project Specifications Concrete Design of Piperack Members (DAY-2) Introduction about IS:456 & SP:16 Provisions(DAY-3)
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Introduction
What is called PIPERACK ? PIPERACK is a structure whose basic geometry is like a Portal Frame
having Multi-tiers which are provided to support pipings , cable trays and (with) Finfan coolers or (Without) coolers.
CLASSIFICATION OF PIPERACK Based on plant layout
ISBL (Inside Bat. Limit) & OSBL(Outside Bat. Limit)
Based on Utilities Supported Non Fin fan & Fin fan piperack
Based on Materials used for Members
Concrete (Precast or Cast-insitu) , Steel & Composite(Steel+Concrete)
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Introduction & Layout
Following Preliminary Informations required from Piping
Screen dumps or P65 drawings showing C/s OF Piperack with different tiers & elevations.
Line size , Max. unsupported spacing/span ,Piping class & state(Hot or Cold), Flow direction i.e supply or Return , Insulation details
Space required for Electrical cable trays. Fireproofing requirement based on line contents for Steel Piperack
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Introduction & Layout
Braced bay location:
Brace bay is nothing but it is bay supporting Piping anchor points.
Location shall be generally provided by Piping Specialist.
For Economy the anchor points for the same line shall be provided at staggering positions.
Expansion Bay :
Normally to be decided by Civil/Structural specialist. Normally the same shall be provided at every 40 to 50 Mt.
Longitudinal RC beam Elevations :
Normally to be provided in the center of Two tiers. Always Larger diameter of Pipes shall be routed near to Columns.
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PIPERACK LOADING (REFERENCE : 3PS-CA-001)
For on-plot piperacks minimum vertical load of 1.7 kN/m2 on plan area shall be applied at each piperack level, unless definitive loads are available from Piping Group. A concentrated load shall be added for pipes 12 in. dia. or larger.)
For off-plot piperacks a vertical load of 2.5 kN/m² on plan area shall be applied at each piperack level, unless definitive loads are available from piping group. Concentrated loads for 14 in. dia. or 16 in. dia. pipes shall also be considered.
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The horizontal friction load applied at each level shall be the greater of 7.5% of the total pipe weight or 30% of the operating pipe weight of any number of lines known to be
moving simultaneously in the same direction. For on-plot pipe racks the longitudinal beam struts shall be
designed for a vertical load of 50% of the load carried by the most heavily loaded transverse beam. This load should not be added to the design load for column or footings. For off-plot pipe racks, longitudinal beam struts shall be designed for vertical and horizontal loads imposed by expansion loops, located by piping group.
Introduction contd.
PIPERACK LOADINGS
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PIPERACK LOADINGS
All piperack longitudinal beam struts shall be designed for a compression load of 15% of the maximum adjacent column load at beam level.
The horizontal load on piperack anchor bays shall be the greatest of:-
Anchor force from pipe stress (These shall include start-up and shutdown conditions). or
7.5% of piping vertical load between expansion joints or
40 kN applied uniformly at each level.
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PIPERACK LOADINGS
Piperack designs shall be checked, when actual pipe loads, friction and anchor forces are known.
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WIND LOADING CALCULATIONS
Wind loads acting on Piperacks shall be in accordance with IS:875-III-1987
Basic Wind speed : Vb = 50 m/sec Risk coefficient -K1 = 1.08 Height & Terrain Factor K2 = Cat.2,Class-A,Table-2,IS875 Topographic factor k3 = 1.0 Design Wind speed Vz = Vb x K1 x k2 x k3 Design Wind Pressure Pz = 0.6 x Vz²
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WIND LOADING CALCULATIONS
Wind force for Piperack Individual members Frame wise Individual Members
* Column & Beam Members(cl.6.3.3.2(b))
Normal force=Cfn x Pz x K x b ……..Kn/m
Transverse force=Cft x Pz x K x b ……..Kn/m
Cfn , Cft = force coefficients
K= Reduction factor for individual members(Table-25,pg.44)
b=width of member across wind direction
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WIND LOADING CALCULATIONS
Wind force for Piperack Frame wise (CL.6.3.3.3 & 6.3.3.4)
Solidity ratio= area of members in direct exposure/Overall area
Force coefficients(for 1 Frame) = Reference table:28(pg.46)
for more than one frame
Frame spacing ratio =c/c dist of frames/least overall dim of frame measured at right angle to direction of wind
Refer Shielding factor based on solidity ratio & Frame spacing ratio(Refer Table:29 of Pg. No. 46 of IS:875-III)
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WIND LOADING CALCULATIONS
Wind Force on Fin Fans
F (Total Wind Force) = Cf x Ae x Pz ……..Kn
Cf(Max) = Force coefficients =0.95 (Table:4)
Ae = Effective Frontal Area
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WIND LOADING CALCULATIONS
WIND LOADINGS FOR PIPES
The transverse wind load on piping shall be applied on a projected area equal to the diameter of the largest pipe including insulation where applicable plus 10% of the usable width of the piperack, where the usable width of the piperack is defined as the distance between inside faces of piperack columns less clearance between columns and piping.
Where pipe sizes are unknown projected area shall be based on a 12 in. dia. pipe plus 50mm insulation.
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Cable Tray Loads
A minimum cable tray load of 1.0 kN/m2 per tray layer shall be used for electrical/instrument trays.
The transverse wind load on cable trays shall be applied on a projected area equal to the height of the tray plus 10% of the net width of cable way dedicated to trays.
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Introduction to UBC-94
International Conference of Building Officials(ICBO) Publishes the family of Uniform Building Codes
There are diff. Types of Uniform codes are available
Uniform Building Code : Volumes- 1,2,3 : The most Widely adopted model Building Code in the United States.
Volume-1 : Administrative , Fire and Life safety , Field Inspection provisions
Volume-2 : Structural Engineering Design provisions
Volume-3 : Material , Testing & Installation Standards
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Seismic loads(As per UBC-1994)
V = Z x I x C / Rw (For Piperack structure) V= Design Base shear Z = Seismic Zone factor = for Zone-3 it is 0.3 (Table:16 I) (pg no.34) I = Importance factor = 1.25 (Table :16 K) (pg. No:35) C= Numerical Coefficient =1.25 x S / T 2/3 (Need not exceed 2.75) S=Soil Site Coefficient = 1.0 (Table :16 J) T= Fundamental period = Ct x hn 3/4 Ct = 0.0731 (For RC Mom. Frames),0.0853(Steel Moment
Frames),0.0488 for all other buildings hn = Height in meter above the base W = Dead & Normal operating gravity loads Rw = Response Modification Factor depending on OMRF,SMRF &
Braced bay types (Table :16 N)(Pg:37) Vertical distribution of base shear force shall be in accordance with
formulas (28-6) ,(28-7) & (28-8) of the UBC,Section-1628
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Seismic loads(As per UBC-1994)
If T < 0.7 seconds Ft =0
If T > 0.7 seconds Ft =concentrated force @ top=0.07xTxV OR Need not exceed 0.25 V
Remaining Base shear Force shall be distributed as given below Fx = (V-Ft) x Wx x Hx / Sum( Wi Hi)
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Seismic loads(As per UBC-1994)
V = Z x Ip x Cp x Wp (For Fin Fan ) Fp= Lateral Force Z = Seismic Zone factor = for Zone-3 it is 0.3 (Table :16 I , Pg. No. 34) Ip = Importance factor = 1.5 (Table :16K , Pg. No. 35) Cp= Horizontal Force Factor =0.75 (see note below) (Table :16O,Pg.38) Wp= Weight of Finfan or component
NOTE : For flexibly supported fin fans with fundamental period greater than 0.06 seconds , use Cp equal to twice the value as shown.
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LOAD COMBINATIONS (FOR RC DESIGN & FOUNDATION)
Erection Condition: (Don’t include wt. Of contenets)1. U = 0.9 x D + 1.3 x W (ACI) OR 1.5 x W (IS:456)2. U = 0.9 x D + 1.43 x W (ACI) OR 1.5 x W (IS:456) D= Empty load of piping shall be 60% of piping Test Condition: U = 1.4 x D + 1.4 x TL + 1.7 x L (ACI) OR 1.5 (D+TL+L) (IS:456)• U = 0.75(1.4D + 1.4 TL+ 1.7 L+0.5x1.7W) (ACI) OR 1.2(D+TL+0.5W)(IS456)Operating Condition: U = 1.4D + 1.7 L (ACI) OR 1.5(D+L) (IS:456)• U = 0.75(1.4D +1.7 L+1.7W) (ACI) OR 1.2(D+L+W) (IS:456)• U=1.4(D+L+E)(ACI) OR 1.2 (D+L+E)(IS:456)• U=1.4(D+T) (ACI) OR 1.5(D+T) (IS:456)• U=0.75(1.4D+1.4T+1.7L) OR 1.2(D+T+L)• U=0.75(1.4D+1.4T+1.7L+1.7W) (ACI) OR 1.2(D+T+L+W) (IS:456)• U=0.75(1.4D+1.4T+1.7L+1.87E)(ACI) OR 1.2(D+T+L+E) (IS:456)• Where U=Reqd. strength to resist factored loads in accoordance with
the ACI-318M & UBC OR IS:456
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LOAD COMBINATIONS FOR CONNECTIONS
Connection Design as per UBC 1994 clause 2211.5.1 & 2211.8.3.1
37 or 38) DL + Oper. Load (+/-)3(Rw/8)xSeismic in N/S dir.(+/-)(Rw/8)xSL in E/W dir
39 or 40) DL + Oper. Load (+/-)3(Rw/8)xSeismic in E/W dir(+/-)(Rw/8)xSL in N/S dir
41 or 42) DL+Oper. Load+ 50%Live Load (+/-)3(Rw/8)xSL in N/S(+/-)(Rw/8)xSL in E/W
43 or 44) DL+Oper. Load+ 50%Live Load (+/-)3(Rw/8)xSL in E/W(+/-)(Rw/8)xSL in N/S
Column&Bracing Strength in Compression as per UBC 1994 clause 2211.5.1&2211.8.2.3
45 or 46) DL+Oper. Load+ 0.7xLive Load (+/-)3(Rw/8)xSL in N/S(+/-)(Rw/8)xSL in E/W
47 or 48) DL+Oper. Load+ 0.7xLive Load(+/-)3(Rw/8)xSL in E/W(+/-)(Rw/8)xSL in N/S
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LOAD COMBINATIONS FOR CONNECTIONS
Column&Bracing Strength in Tension as per UBC 1994 clause 2211.5.1 & 2211.8.2.3
49 or 50) 0.85xDead Load (+/-)3(Rw/8)xSL in N/S(+/-)(Rw/8)SL in E/W dir 51 or 52) 0.85xDead Load (+/-)3(Rw/8)xSL in E/W(+/-)(Rw/8)SL in N/S
Column&Bracing Strength in Tension as per UBC 1994 clause 2211.5.1&2211.8.2.3
49 or 50) 0.85xDead Load (+/-)3(Rw/8)xSL in N/S(+/-)(Rw/8)SL in E/W dir
51 or 52) 0.85xDead Load (+/-)3(Rw/8)xSL in E/W(+/-)(Rw/8)SL in N/S
Manual Check Requirements as per UBC 1994
1. Slenderness Ratio Check as per clause 2211.8.2.1
2. Bracing Check for reduced permissible stress as per clause 2211.8.4.1.1
Note:Application of seismic force in both direction shall be checked by designer.
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Example for strength check as per connection design forces
Column subjected to compression and Bending Moment (Example)
Section Used,Plate Girder 1200x25 + 400x45 (T&B)Column member subjected to Compressive force and bending MomentMaximum Axial compression = 4108.6 kNAllowable Axial compressive stress = 81.42 N/mm2Area of the Section Used = 63750 mm2Taken from STAADPro resultsAxial Compressive Strength = 1.7 x Fa x A as per UBC Clause 2211.4.2 = 8823.89kN
Hence, Safe Maximum Bending Moment =4368 kN.mFlexture Strength = Zp x Fy
Plastic Section Modulus of the section = Zp =2.85E+07mm3Yield stress of the material = Fy =250 N/mm2
Flexture Strength =7122.50 kN.m Hence, Safe