Post on 05-Apr-2018
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ABSAthe pressure equipment safety authority
Pneum at ic Test ing
Presented by:
Djordje Srnic, Manager of Design Survey
Code Update Seminar
Edmonton, October 05, 2010
Calgary, October 07, 2010
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Objectives
Understand
Purpose of Pressure Testing
Regulat ion Requirem ent s
Hydrostatic vs. Pneumatic Test
Risk
Pneum at ic Testing Specific Requirem ent s
Registrat ion Requirem ent s
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To verify
system integrity
leak tightness
What is the Purpose of Pressure
Testing?
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Why Pressure testing is required?
The last physical quality test in thefabrication process
Performed prior to placing the system into service
Done in controlled environment
Preferred mainly due to safety
considerations
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Regulation Requirements
Section 3 0 of PESR 4 9 / 2 0 0 6(1)All pressure piping leak tests must be conducted usingthe hydrostatic method.
(2)Despite subsection (1), the Administrator may accept,for a specific pressure piping system, alternative testmethods that are allowed in a code or standard that isdeclared in force.(3)A pressure piping system shall not be tested at atemperature that is colder than its minimum designtemperature.
(4)When conducting pressure tests, the ductile-to-brittletransition temperature and the possibility of brittle fracturemust be considered by the contractor.
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Alternative test Methods
Pneum at ic te st
Hydrosta tic- Pneum at ic Test
I nit ial Service Lea k Test
Sensitive Leak Test
Alternative Test Methods in Lieu ofHydrostatic Leak Testing for a Closure or
Tie- I n W elds
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Why Pneumatic Testing is
Alternative to Hydrostatic Test?
Difficulties w ith hydrostat ic te stingSupply & disposal of water, disposal of fluidadditives
Water leak can cause equipment damageFreeze susceptibilityStructural support limitationsContaminationOperational impacts - process contaminant
Affect dry-out of internal refractory liningsAvailability a ir is re adily available ,clean
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Hydrostatic vs. Pneumatic Test
Qualitative Differences
Water is not compressibleEnergy storage is minimalPressure changes finite amount by infinitesimal
change in volumeWater filled balloon does not pop nocompressive energy
Air is compressibleEnergy storage is large
Pressure change proportional to volumechangeAir filled balloon pops large, instantaneousenergy release
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Risk
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Dangers Associated With
Pneumatic Testing
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Primary concerns
Pressure wave
Flying debris
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Damage correlation
0.04 psi Very loud noise [143 dB], sonic boom glass failure0.10 Breakage of small windows under strain0.15 Typical glass pressure induced failure0.30 10% of windows broken0.50 Windows shattered, minor damage to house structures0.70 Upper limit for reversible effects on humans1.0 Partial demolition of houses2.0 Partial collapse of walls and roofs of houses2.4 Eardrum rupture
2.5 Threshold for significant human lethality3.0 Steel frame building distorted and pulled away from
foundation
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Flying Debris
Fragmentation Criteria
Primary fragments
Secondary fragments
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Pneum at ic Test Procedure ( PTP)
Registration is Required
De sign Survey w ill review and register PTP if
p>315 psi oror
V>0.5m3
oror
Company does not have Standard PTP included intheir quality program and piping system p=
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Pneumatic Test Procedure Must
Provide technical justification for not completingthe hydrostatic pressure test.
Provide a w rit te n te st procedure that w ill fullyaddress the technical and safety considerationsfor the test.
Be acceptab le to the ow ner. The ow ner of thepiping system must review the circumstancesand decide to accept the risk of nothydrostatically testing the piping system
Be review ed and accepted by ABSA.
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Technical and Safety
Considerations
De fine test boundaries ( List of piping & Pressurevessels included in the test)
Define system volume and test fluidCalculate test pressure
Pressure re lief devices ( m ax set pressure at1 1 0 % of the te st pressure )
Safet y pre cau tions ( safe dista nce, bar ricades,
marking the test area, hours when test may beconducted, w ork ing & eva cuation procedures,etc.)
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Technical and Safety
Considerat ions ( cont d)
Steps to minimize the chance of brittle failureduring a pneumatic test
List of all personnel allow ed w ith in test ing ar ea ,requ ired training and com petences
Precautions taken to prevent gas expansiontemperature drop and thermal stress due thermalgradients
Me thod of testing w ith details of pre ssure steps,holding time, inspection methods, depressurizing
Test accept ance criter ia and records ( creat ing andm ainta ining records)
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Test Pressure
P t = 1 .1 x P x Sat/ SdtPt = test pressure
P = Maximum allowable working pressure
Sat = Allowable stress at the testtemperature
Sdt = Allowable stress at the design
Temperature
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Methodologies for Defining Safe
Distance
EPC companies have their own standards& methods
End users have their own standardsNASA method
US DOD method
ASME PCC-2 Article 5.1 method
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Common Safe Distance Analysis
for Pneumatic Test
Define system volume and test fluid
Calculate test pressure
Calculate stored energy
Define equivalent amount of TNT
Calculate the safe distance
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Example:
Air; p= 3 1 5 psi; V= 0 .5 m 3
Stored energy = 1,677 kJ
TNT equivalent = 0.393 kgSafe distance according to:
US DOD method - R = 18.1 [m]
NASA method - R = 19.8 [m]
ASME PCC-2 method - R = 14.7 [m] ** R = 30 [m] because stored energy is
E=1,677 [kJ] < 135,500 [kJ]
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ABSA is considering Using the
Equivalent Stored Energy
E= 1 ,6 7 7 [ kJ] for piping syste m w ithp= 3 1 5 [ psi] and V= 0 .5 [ m 3 ]
Graphed stored energy for combinationof volum e and pressure w hich w ouldcreate the same stored energy as piping
system w ith p= 3 1 5 [ psi] and V= 0 .5 [ m 3 ]
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Graph
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Conclusion
Knowledge of Regulation requirements
Understanding the Risk
Competency of personnel
Understanding technical and safety
considerations
Deve lopm ent and I m plem ent at ion of te st
procedure ( before , during and aft er thetest)
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Questions