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API Standards for Coiled API Standards for Coiled TubularsTubulars
Roderic K. Stanley, Ph. D, I. Eng. SPE
International Oilfield ServicesInternational Oilfield ServicesChm: API Resource Group for Coiled Tubing
[email protected] Nov 05Aberdeen Nov 05
Coiled Tubulars?Coiled Tubulars?•• Coiled Tubing (CT)Coiled Tubing (CT) - small dia – 4.5-in. ERW
carbon steel tubing used in numerous ways• CT55, CT70, CT80, CT90 (in RP 5C7)•• Coiled Line Pipe (CLP)Coiled Line Pipe (CLP) – small dia – 6.625-in.
ERW carbon steel tubing used as umbilicals, flowlines, etc.
• X52C, X56C, X60C, X65C, X70C, X80C –follow the 5L classifications for line pipe
•• Currently Currently ExcludesExcludes: short welded lengths of ERW and smls.
SPESPE--IcotaIcota--Aberdeen Nov 05Aberdeen Nov 05
CT and CLPCT and CLPNote..From 1944
A cycle here is not…..
Coiled Coiled TubingTubing
CLP
From 2000
CLP…a cycle here…a cycle hereCoiled line Pipe SPESPE--IcotaIcota--Aberdeen Nov 05Aberdeen Nov 05
A Little Background…..A Little Background…..
SPESPE--IcotaIcota--Aberdeen Nov 05Aberdeen Nov 05
Where we were in 1998…….Where we were in 1998…….•• ResourceResource GpGp. for Coiled Tubing formed 1996. for Coiled Tubing formed 1996•• SPE 46019 “SPE 46019 “Progress Towards API Specifications for Progress Towards API Specifications for
Coiled Tubing and PipeCoiled Tubing and Pipe” by ” by SasSas--JaworskiJaworski/Stanley/Stanley•• Working on Working on RP 5C7RP 5C7 –– “catch all” RP “catch all” RP –– one of a kind.one of a kind.•• Working on Working on Spec 5LCPSpec 5LCP –– Coiled Line Pipe thought to Coiled Line Pipe thought to
be very importantbe very important•• Working on Working on Spec 5STSpec 5ST -- Coiled Tubing Spec was Coiled Tubing Spec was
shelved in order to get 5LCP into print.shelved in order to get 5LCP into print.•• Approved Approved ––to work on to work on RP 5C8RP 5C8 (Care, Maintenance (Care, Maintenance
and Inspection of Coiled Tubing*) and Inspection of Coiled Tubing*) * Later changed to * Later changed to “Coiled Tubulars”“Coiled Tubulars”
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Current API OrganizationCurrent API OrganizationSPESPE--IcotaIcota--Aberdeen Nov 05Aberdeen Nov 05
You are here
Fun stuff here
Kinda wild here too
And we are in here too
The new guys on the block
CT CLP
API representation API representation -- todaytoday•• PurchasersPurchasers: Service Companies, Major Oils,
Pipeliners. •• OperatorsOperators: Major Oils•• Mills:Mills: Manufacturers.•• ConsultantsConsultants: Welding, Collapse•• ObserversObservers: MMS, DoT, Rosen, Sumitomo•• InspectionInspection: Tuboscope, Patterson (RD/Tech),
Intl. OilFld Svcs•• API:API: attend all meetings
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Current Documents Current Documents -- 5C75C7
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• API RP 5C7 – CT55-90 only (1996)
• Tensiles beforebefore bending• Renewed 2001• Remain in force until
either updated or withdrawn
• Operational sections transferred to a Committee 6Committee 6 document on well servicing
• Corrosion and Collapse transferred to RP 5C8
Current Documents Current Documents –– 5LCP (1999)5LCP (1999)• Converted from 5L (41st Ed)• Dropped all mfg except ERWERW• Added SkelpSkelp--end weldend weld, NDE NDE
not in 5Lnot in 5L, 15 min hydro at 15 min hydro at 80% SMYS,80% SMYS, butt welding to butt welding to API 5L/1104API 5L/1104, tensiles at “mill stops”.
•• Charpy testsCharpy tests at customer request.
• Can class CT55CT55--8080 as X52CX52C--X80C. (No X42C)X80C. (No X42C)
•• Up for 5Up for 5--yr reviewyr review
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In the Works…In the Works…API Spec 5STAPI Spec 5ST
(Specification for Coiled Tubing)
•• ((5LCP pbl conv to CT))• Was Voted in 2001• Not enough votes• “Not tight enough”• Put on hold • Pressure to re-introduce
in 2003• New chm. found 2005• Work to begin now
API RP 5C8API RP 5C8(Care, Maintenance, Inspection of Coiled Tubulars)
•Grades up to CT110
•Mechanicals, inc CSA, defect removal definitions
•Corrosion & Mitigation
•Butt Welding and its NDE
•Tube NDE – Visual/Dimensional
EMI, Prove-Up
• Assessment of Used CT
• Collapse from 5C7 into Appendix
• Defect Pictures in appendixSPESPE--IcotaIcota--Aberdeen Nov 05Aberdeen Nov 05
Why RP 5C8?Why RP 5C8?• Repeated and unidentified field failures
• Provide minimum requirements for field protection of C-Tubulars
•Provide field welding procedures
•Provide field general NDE procedures for common EMI EMI systems.
•Provide NDE equipment standardization/calibration requirements
•Aim to replace RP 5C7
COILED TUBING FAILURES 1987-98
0
10
20
30
4050
60
70
80
90Corro
sion
Rig Opera
tions
Manufactu
ring
OD wea
rTens
ileButt W
eld
OC
CU
REN
CES
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Corrosion and Corrosion and MitigationMitigation
Pits/cracks on OD→
Pitting at root of flash column, + crack
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Mitigation and PreventionMitigation and Prevention• Flushing – high pH
fluids• OD Cleaning and
coating• ID Cleaning and coating• Air drying• N2 dry and backfill• Relative Humidity of
flush/backfill measurement
• Dew point measurementRH meter
SPESPE--IcotaIcota--Aberdeen Nov 05Aberdeen Nov 05
TubeTube--Tube Butt Welding……..Tube Butt Welding……..• Industry welding sub-
committee formed• WPS and PQR contents
established• Manual and Orbital butt
welds• ..not ADB or other exotic
methods• Borrowed material from
Icota Welding document
Bonded interface
400μm
Amorphous Bond in CT
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………….and its NDE………….and its NDE
Phased array weld inspectionGeometry considerations
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16 element linear array Sweep from 40 to 70 degrees
Status today……Status today……5LCP 5LCP –– voted late 2004voted late 2004•• changeschanges out for vote• Added more ultrasonic
NDE, esp for butt welds• Add X90CX90C grade• Provide for torch-cut
ends• Reduce acceptable min.
wall from ––12.5%t12.5%t to ––10%t.10%t.
RP 5C8 RP 5C8 –– Voted late 2004 Voted late 2004 • changeschanges out for vote• more “shoulds” and no “shalls”. • Added definitions of “cycle” and “critical sour well“ (AEUB)• Added pictures of common defects in an appendix
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Status today..(2)2)PSLs might includePSLs might include
•Additional UT of SE weld
•Additional UT of Butt weld
•Restricted tensile ranges (for sour service)
•Restricted hardness ranges (same)
•Additional microhardness readings
• Final NDE Inspection after hydro
• Longer/higher pressure test
5ST5ST• Chm. found midyear• Cover mfg, grades,
testing, inspection• Include Product
Service Levels?
SPESPE--IcotaIcota--Aberdeen Nov 05Aberdeen Nov 05
5C8 5C8 -- Equipment Equipment Standardization & CalibrationStandardization & Calibration
From RP 5A5…….• All equipment calibratedcalibrated at regular intervals• All equipment standardizedstandardized at regular intervals• Reference standards & reference indicators
maintained.• EMI unit, UT Compression wall gauge, UT shear
wave unit, RT unit, Mag. particle yokes, pit depth gauges.
• All Operators trained, qualified and certified
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Examples Examples -- CalibratableCalibratableEquipmentEquipment
EMI equipment for full length CT inspection – now defunct UT Butt weld inspection
equipmentSPESPE--IcotaIcota--Aberdeen Nov 05Aberdeen Nov 05
Tubing Tubing Assessment Assessment TableTable--5C85C8
Classified sections of tubulars from TFL and NDE, not just either one
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What Do You Do When You Find What Do You Do When You Find an Imperfection?an Imperfection?
• Need to notify owner of tubing
•Check the inspection table
• Use a Fatigue model
•Make assessment including fatigue model and defect size
•Repair the damage SPESPE--IcotaIcota--Aberdeen Nov 05Aberdeen Nov 05
5C8 Appendix5C8 Appendix
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Training and Certification 1Training and Certification 1• All Inspectors qualified and certified…..• Use ASNT Scheme (TC-1A or CP-189)• 0r PCN Scheme• Level 1• Level II• Level III• In EMI, UT, MT, PT, RT• Nonlevelled courses in Visual, Dimensional and
Hardness Testing
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Training and Certification 2Training and Certification 2Inspector should be;Inspector should be;
1. Trained in all inspections used on CT/CLP
2. T/C to Level II under ASNT or PCN regime
3. Cognisant of accept/reject/derating criteria
4. This implies that the SpecificSpecific part of the certification exams should cover knowledge of the equipment used, and the accept/reject criteria.
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Typical Training Course Typical Training Course OutlineOutline
• Coiled Tubulars• Fatigue Models• Common defects• Effect of defects• PT course (G, S, Pr)• RT course (G, S, Pr)• UT course (G, S, Pr)• MT course (G, S, Pr)• EMI course (G, S,Pr)
• Visual Inspection
• Hardness Testing
• Other, as needed
Similar to classes Similar to classes developed for DSdeveloped for DS--1 1 or NSor NS--22
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Collapse in RP 5C8Collapse in RP 5C8• Moved from bodybody of 5C7 to AppendixAppendix of 5C8• Added disclaimer regarding origin of collapse
equations for new and used coiled tubing
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Collapse appendixCollapse appendix•Vast amt of high level work done on new/old tubular collapse data
•New equation developed for API 5C3/ISO 119400
•Eliminates 4 equations for Yield strength, plastic, transition, and elastic collapse regimes
•Replaced them with one (more complex) equation
•Tamano 4, generalized by Dr. Frans Kever ( KGT)
• Work yet to be defined for normalized ERW tubing SPESPE--IcotaIcota--Aberdeen Nov 05Aberdeen Nov 05
Possible new API RGCT Possible new API RGCT Approach…..Approach…..
• Obtain results from KGT (2000 data points), which includes all data points at higher measured values for concervatism.
•Use results for more roundedmore rounded Stress-strain curves
•Add existing Avakov-Timoshenko correction for OvalityOvality
•Add existing Avakov correction for coiled tubing usageusage
This is the same approach as was used to generate the original This is the same approach as was used to generate the original values in 5C7, but there, the old equations from 5C3 were values in 5C7, but there, the old equations from 5C3 were used. Here, we place them with KGTused. Here, we place them with KGT
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The equations……CollapseThe equations……Collapsepc,ult = (pe+py)/2 – [(pe-py)2/4 + pepyHult]1/2 (A1)
Where
pe =1.08[2E/(1-ν2)][(Do/t)-1 (Do/t - 1)-2] (A2)
py = 2fy[Do/t – 1][Do/t]-2[1 + 1.5/(Do/t –1)] (A3)
Hult = 0.071Ov + 0.0022 ec – 0.018 rs (A4)
And
Do = actual average diameter, E = Young’s Modulus
ec = eccentricity in % as (tmax-tmin)/tav fy = Actual API Yield stress.
Hult = is a decrement factor Ov = Ovality% as (Do,max-Do,min)/Do,av
pc,ult = Ultimate collapse str, pe = Collapse str for elastic elastic failure
py = Collapse str for yieldyield failure, rs = Residual stress
t = Average wall thickness ν = Poisson’s ratio.SPESPE--IcotaIcota--Aberdeen Nov 05Aberdeen Nov 05
Collapse Collapse DesignDesign EquationsEquations
pc,des = (kepe+kppy)/2 – [(kepe-kppy)2/4 + kepekppyHdes]1/2 (A5)
where
Hdes = Decrement factor (varies with manufacturing process).
ke = Downrating Factor for elastic collapse
kp = Downrating Factor for plastic collapse.
One challenge is to define H for a coiled tubular. Is thevalue for normalized, not hot/cold straightened applicable?
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