Overpressure Case

8/17/2019 Overpressure Case

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FACILITY INTEGRITY ASSESSMENT CASE

VESSEL OVERBURDEN

UNDER RIVER PRODUCTION FIELDS

JR Engineering Ramírez, J., M.Sc., P.E.

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OBJETIVE

For the overpressure´s incident, analyze the impact over the vessel

´s structural integrity and give options remedial.

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What would be the approach, ASME orAPI?

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ASME

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API

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SCOPE ASME B PV S VII API-510

GeneralDesign and construction of new

equipment

Inspection, repair, derating,modification, alteration of in-

service equipment.

InspectionsFocused in the quality controlduring construction process

Focused in the conditionmonitoring during in-service life.

SCOPES


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Ok, is API

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API-510 ROLES

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API-510 ROLES

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API-510 ROLES

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API-510 ROLES

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API-510 ROLES

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API-510 ROLES

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Who am I?

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Now, How do it?

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ASSESSMENT APPROACH

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54 ksi

77% Ts

Ts = 70 ksi

Ys = 38 ksi

1 0 0 p

s i

5 0 p s i

MAWS = 20 ksi

R/t for X-01

stress for OP


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25

yield Stress 38 ksi

Tensile Stress 70 ksi

Fracture

R e s i l

e n c e

RemanentToughness

25%

Overpressure Stress 54 ksi

LostToughness

75%


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FAILURE ASSESSMENT DIAGRAMSAPPROACH*

*Rolfe, S. and Barsom, J. (1999). “Fracture and fatigue control in structures ”, Applications of Fracture Mechanics, ASTM.


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ENGINEERING CRITERIAL FORTHE ASSESSMENT

• The toughness governs the planar defects, and the cracks are planar defects

• The yield strength governs the volumetric defects, and based in the available evidence, the volumetrics defects not exist inthe vessel

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For overpressure, the hoop stress is critical, for thus the longitudinal welds are critical

• The lost of toughness, not is easy to determinate, without a destructives testing (tensile test and charpy V-notch test), but theASME specification for AS516-70´s plates, is nearly 15 ft-lb for CVN test

• The empirical correlations between CVN test and Kc (toughness) are available*

• The total toughness is used for calculated the FAD for the pre-incident materials properties

• Conservatively, we could to do a lineal proportion between the overpressure induced stress and the tensile strength.

• If the area under of stress-strain curve until the tensile stress is the total material toughness, until the level stress induced forthe overpressure is proportional.

• The 25% of toughness is used for calculated the preliminar FAD post-incident material properties


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RESULTS

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Failure zone Pre-incident leak zone

Pre-incident rupture zone

Post-incident leak zone

Post-incident rupture zone


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And now?

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ENGINEERING ACTS FOR THEASSESSMENT

• Inspect with RX the longitudinal welds of vessels

• Apply hardness test (HT) in interest areas

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Visual inspection (VT) in the mechanical unions between internals and shell

• Apply penetrant testing (PT) in the longitudinal and girth welds

• Determinate the flaws dimensión with ultrasonic testing (UT - phase array)

• Re-assessment of the new evidence

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If all is ok, test pressure

• Fit for service


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Questions?

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Thanks!

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Documents

Overpressure Case