HCAs & Pipeline Assessment Intervals Is There a Need for
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Transcript HCAs & Pipeline Assessment Intervals Is There a Need for
HCAs & Pipeline Assessment Intervals
Is There a Need for Change?
Richard B. Kuprewicz
President, Accufacts Inc.
For Pipeline Safety Trust New Orleans Conference 11/20 & 11/21/08
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Is There A Need For Change?
The Answer is yes!
Different yes for many sides/factions in this room
Will briefly present
Short regulatory perspective
Summary on integrity inspections
Weaknesses in present approach
Recommended changes
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Current Federal Regulations
Liquid Integrity Management (49CFR195.452)
Phased (via Large / Small Operator) Regulation in 5/29/2001 & 2/15/2002
7 year Baseline assessment
Large operator 50% by 9/30/2004, all by 3/31/08
Small operator 50% by 8/16/2005, all by 2/17/2009
~ 5 year maximum reassessment interval
HCA determined by “could affect”
Captures ~ 43% of liquid transmission pipeline mileage or ~ 73,000 miles
Gas Transmission Integrity Management
PSIA of 2002
10 year Baseline Assessment
50% inspected by 12/17/2007, 100% by 12/17/2012
7 year reassessments
PHMSA Regulation in 2003 (49CFR192 subpart O)
Maximum Reassessment Interval ranging from 7 to 20 yrs based on stress levels
HCA determined essentially by C-fer empirical correlation sweep
Captures about 7% of gas transmission pipeline mileage or ~ 19,000 miles
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Anomalies Requiring Immediate Repair
Liquid Transmission Pipelines
Metal Loss > 80% nominal wall thickness
Remaining strength calc burst pressure at anomaly < MOP
Dent on top of pipe with stress concentrator
Dent on top of pipe > 6% pipe diameter
Anomaly in evaluator’s judgment requires immediate repair
Gas Transmission Pipelines
Remaining strength calc failure pressure at anomaly < 1.1 x
MAOP
Dent on top of pipe with stress concentrator
Anomaly in evaluator’s judgment requires immediate repair
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Liquid - Schedule Repairs
60 – Day Conditions
Top dent > 3% diameter
Bottom dent with stress concentrator
180 – Day Conditions
Dent > 2% diameter affecting curvature at girth/longitudinal seam
Top of pipeline dent > 2% diameter
Bottom of pipe dent > 6% diameter
Calc showing operating pressure less than MOP at anomaly
Metal loss > 50% of nominal wall
Predicted metal loss >50% of nominal wall at another pipe crossing,
widespread circumference or could affect girth weld
Confirmed crack indication
Corrosion of or along a longitudinal seam
Gouge or groove > 12.5% of nominal wall thickness
Other Conditions that may need to be scheduled
E.g., anomaly in or near a casing, crossing, or near another pipeline
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Gas - Schedule Repairs
1 – Year Conditions
Dent on top of pipe > 6% diameter
Dent > 2% diameter affecting pipe curvature at girth or at
longitudinal welds
Monitored Conditions Not Requiring Repair
Bottom Dent > 6% of diameter
Top Dent > 6% of diameter not exceeding critical strain
levels
Dent > 2% diameter affecting curvature at girth or
longitudinal welds but not exceeding critical strain levels
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From PHMSA web site http://primis.phmsa.dot.gov/iim/index.htm
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From PHMSA web site http://primis.phmsa.dot.gov/gasimp/PerformanceMeasures.htm
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Changes Needed In Current IM Approach
U.S. Regs lead the world in area of Integrity Management (IM)
Some areas build off technology developed in other countries
U.S. approach is “Model One” - first of its kind
U.S. has more transmission mileage than other top fifteen countries combined!
Since inception of IM rule through 2007 - Tens of thousands of repairs have
occurred on U.S. pipelines
Liquid Pipelines ~ 26,000 repairs in HCAs, another ~ 59,000 outside HCAs
Gas Transmission ~ 2,500 repairs in HCAs, non HCA repairs not required to be reported
Utilize Learning Curve from First Cycle of IM Assessments
Be aware history doesn’t define the future
Always room for improvement
Need public report repairs by anomaly cause
Limitations / traps in consensus standards
Reward those doing the right thing
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On Setting Regulatory Reassessment Intervals
For corrosion
Address the different risks of selective vs. general corrosion
Selective corrosion can easily substantially exceed 12 mils/yr
Burst calculations models moot if assuming wrong corrosion rate!
PHMSA knows the difference between general and selective corrosion
Respect that PHMSA may be prevented from disclosing corrosion rates in
certain cases
Other time-dependent anomalies need to be addressed
Move to newer stronger pipe (X-70, X-80, X-100, X120)
Delayed third party damage failure much more likely
Stress loading (i.e., land movement) complications
Reassessment interval changes must be based on sound science and sound
assumptions
Are field realities in sync with assumptions in consensus standards?
Given uncertainties of present technology, a safety margin is still required for
re-inspection intervals
Illusionary more “bad” inspections (whether mileage or frequency) are not
better than fewer good inspections matching the risks!
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On Addressing HCAs and Public Confidence
Expand HCAs
Increase the pipeline miles prudently inspected/re-inspected
For Liquids
Address other sensitive areas beyond current HCAs definitions of:
commercial navigable waterways,
populated areas,
unusually sensitive area
Capture High Impact and Risk Areas
E.g., sensitive parklands / protected areas
For Gas
Address the “exotics” where C-fer zone is way too small
More Public Transparency Required
PHMSA must report damage database by anomaly type
Mandate reporting of all pipe repairs, even beyond HCAs, by type of
damage