Post on 08-Sep-2015
PIPE STRESS FUNDAMENTALS
PIPE STRESS MODULES
BASIC CONCEPT TYPES OF STRESS ASME STANDARDS FOR PIPING ALLOWABLE STRESS AS PER CODE NOZZLE LOAD LIMITING CODES PIPE STRESS ANALYSIS
BASIC CONCEPT
TYPES OF LOAD
PRIMARY LOAD
SECONDARY LOADLOADSTRESSRESISTANCE DEVELOPED IN THE MATERIAL AGAINST APPLIED LOAD
PRIMARY LOADS ALL SUSTAIN TYPE OF LOADS
DEAD WEIGHT
PRESSURE
OCCASIONAL LOAD (SESMIC / WIND)
SECONDARY LOADS LOADS DUE TO DISPLACEMENT
THERMAL DISPLACEMENT
DISPLACEMENT DUE TO TANK SETTELMENT
MOVEMENT DUE TO VIBRATION
TYPES OF STRESSPRIMARY STRESS SUSTAIN STRESS OCCASIONAL STRESSSECONDARY STRESS EXPANSION STRESS STRESS DUE TO VIBRATION NOT SELF LIMITING / NON CYCLIC SELF LIMITING / CYCLIC IN NATUR
ANSI STANDARDS FOR PIPING ASME B31.3 :-PROCESS PIPING
ASME B31.1 :-POWER PIPING
ASME B31.4 :- PIPELINE TRANSPORTATION SYSTEM FOR LIQUID HYDROCARBON & OTHER LIQUID.
ASME B31.8 :-GAS TRANSMISSION & DISTRIBUTOR PIPING SYSTEM
STRESS AS PER CODE Sustain stressAs per 31.3 codeWhere:- SL = Sum of longitudinal stress due to wt., pr., and other sustain loadingsFax = Axial force due to sustain loading Am = Metal cross section area (mm2) ii , io, = In-plane and out-plane stress intensification factorMi Mo = In-plant & out-plane bending moment due to sustain loading in (N-mm) Z = Section modulus, (mm3) t = Nominal thickness (mm) Sh = Basic allowable stress at the operating temp. (KPa)Expansion stress rangeAs per 31.3 code SE = Expansion stress range K Pa
Sb = Resultant bending stress St = Torsion stress = 1000 * Mt / 2Z
SA = Allowable expansion stress range SA = f(1.25Sc + 0.25Sh) --- Sc and S h are available in table A1 of 31.3 codeOccasional stress As per 31.1 codeAs per ASME B 31.3 code under clause 302.3.6 only states that the SUM OF LONGITUDINAL STRESSES DUE TO SUSTAINED AND OCCASIONAL LOADS SHALL NOT EXCEED 1.33 TIMES THE BASIC ALLOWABLE STRESS i.e. < K Sh
ALLOWABLE STRESS AS PER CODEALLOWABLE STRESS IN CODE ARE BASES ON MATERIAL PROPERTIES As per the ASME B31.1 ( Minimum of )
1/4TH OF UTS OF MATERIAL AT OPERATING TEMPERATURE
1/4TH OF UTS OF MATERIAL AT ROOM TEMPERATURE.
5/8TH OF YIELD STRENGTH OF THE MATERIAL AT OPE TEMPERATURE
5/8TH IF YIELD STRENGTH OF THE MATERIAL AT ROOM TEMPERATURE.As per the ASME B31.3 ( Minimum of )
1/3RD OF UTS OF MATERIAL AT OPERATING TEMPERATURE
1/3RD OF UTS OF MATERIAL AT ROOM TEMPERATURE.
2/3TH OF YIELD STRENGTH OF THE MATERIAL AT OPE TEMPERATURE.
2/3TH IF YIELD STRENGTH OF THE MATERIAL AT ROOM TEMPERATURE.
NOZZLE LOAD LIMITING CODES Centrifugal pumps API 610 / ISO 5199
Centrifugal compressors API 617
Reciprocating compressors API 618
Steam turbines NEMA SM 23
Air cooled heat exchanger API 661
Fired heaters API 560
LIMITING THE STRESSES AS PER RELEVANT CODE LIMITING THE DEFLECTION SAG AND FOULING LIMITING THE EQUIPMENT NOZZLE LOAD ESTIMATION OF LOAD FOR DESIGNING PIPE SUPPORTS TO CHECK THE PROPER FLEXIBILITY OF PIPING SYSTEM PURPOSE OF STRESS ANALYSIS
PIPE STRESS ANALYSIS INPUT REQUIRED SOFTWARE USED CAESAR II , 4.5 VER. LOAD CASES TO BE ANALYSED OUTPUT OF STRESS ANALYSIS
INPUT REQUIRED STRESS ISOMETRICS LDT AND P & ID EQUIPMENT GA DRAWING MECHANICAL DATASHEET
SOFTWARE USED CAESAR-II ,4.5 VERPIPING INPUT
CAESAR SPREADSHEETNODESDIMENSIONSIZETHICKNESSCORR. ALLOWINSL THKDGN TEMP.OPE TEMPDGN PR.HYDRO PR.MATERIALFLUID DENSITYINSL DENSITY
SUPPORT MODELLINGSUPPORT
EXAMPLE OF SUPPORT ON PIPE Gravity Rest Support
VARIOUS TYPES OF OTHER SUPPORTSSpring Supports Variable and Constant effort
LOAD CASES TO BE ANALYSEDBATCH RUN
RESULT OF ANALYSIS
STRESS ISOMETRIC WITH MARK UP
LOAD SUMMARY SHEET
DATASHEET FOR PIPE SUPPORTS
SPS DRAWING OUTPUT OF STRESS ANALYSIS