2016 OCC Pipeline Safety Conference2016 OCC Pipeline Safety Conference2016 OCC Pipeline Safety Conference2016 OCC Pipeline Safety ConferenceMay 10 through 13, 2016May 10 through 13, 2016May 10 through 13, 2016May 10 through 13, 2016

Corrpro

Hector Hernandez

Matthew Coburn

Who is Corrpro?

• The world’s leading provider of corrosion control and integrity engineering services

• Exclusively involved in condition assessments and corrosion prevention with over 50 years of experience

• Corrpro offices:• US = 26• Canada = 10• UK = 3• Saudi Arabia = 1

• 887 employees (500+ engineers, technicians and support staff) • Specific expertise in pipeline / tank integrity and asset management

Corrpro Technologies & Services

• Corrosion prevention engineering

• Corrosion and soil/groundwater laboratory testing

• Material selection

• Cathodic protection design and construction (EPC)

• AC and DC interference modeling and mitigation

• Internal corrosion control programs

• Protective coating technology

• Condition assessments

• Corrosion monitoring systems

• Pipeline integrity management programs

An Introduction to AC Interference Effects on Pipelines

• Background

• Utilidors

• Criteria

• Options

• Testing

• Mitigation

• Monitor

Many Complex Factors Contribute to AC Interference & Determining Effective Mitigation

• Coating Quality and Cathodic Protection

• Pipeline vs. Transmission Line Geometry and Proximity

• Length of Parallelism and Crossings

• Variations in Soil Resistivities

• Electrical Breaks in Pipeline, e.g. Isolation Flanges

• Transmission Line Conductor Configuration

• High Steady State Current / High Voltage Magnitude

• Transmission Line Phase Transpositions

• Electrical Fault Currents

• Tower grounding and Shield/Sky Wires Connecting Towers

Causes:“Utilidors” - Joint Utility Corridors

• Rights-of-way are increasingly difficult to obtain for new pipeline projects and for new power line projects

• An attractive option is shared rights-of-way, i.e. “Utilidors”

• Future projections are for more and more Utilidors

• Utilidors can range from a few thousand feet to 1000+ miles

Causes: “Utilidors” - Joint Utility Corridors

• Shared ROW

• Congestion

• Demand

• Coatings

• Growth

• Regulated

Causes: “Utilidors” - Joint Utility Corridors

UtilidorsCome in All Shapes and

Sizes

AC Mitigation & Control - North American Standards/Codes and Regulations

• NACE International SP0177

• IEEE – Institute of Electrical Electronic Engineers

• CSA – Canadian Standards Association

• CFR 192 & 195

• OQ, Operator In-House

• 15 VAC Above and Below Grade

• AC Current Density: 20 A/m² - 100 A/m²

• Coating Stress Voltage: 3,000 to 5,000 volts for FBE

Safety: AC Interference Concerns

Safety – Step & Touch Potentials

• General Public

• Company Personnel

• Livestock & Other Animals

Pipeline Integrity / Asset Protection

• Impact on CP effectiveness & monitoring

• AC Corrosion

• SCADA & Other Equipment Reliability

• Coating Damage

• Pipe Wall Integrity

Steady-State AC Interference on Pipeline from Changing Electromagnetic Field

Magnetic Field Produced By

AC Current In Overhead Lines

Pipeline

Soil

Options and Solutions

• AC Interference Causes & Concerns

• Induced AC

• Power Line Faults

• AC Current Densities

• AC Interference Mitigation Solutions

• Front-End Engineering Analyses

• Materials and Methods

• Safe Construction Practices

Step-Touch Potential (Non-Insulated)

Step-Touch Potential (Insulated)

AC Impact From A Power Line Fault

Fault Current

Shield (“Sky”) Wire To

Adjacent Towers

Counterpoise Cable To

Adjacent Towers

Underground High-Voltage AC Transmission Systems

PipelinePipeline

A

B

C A

B

C

Copper Ground Cable (Typ.)

PipelinePipeline

A

B

C A

B

C

Steady-State

Power Line to Ground

Fault

High Voltage Transmission Line Down

AC Corrosion: How Do You Know?

AC Corrosion:

AC Corrosion:

AC Corrosion:

Location of AC corrosion indication detected from DCVG

Help! Help! Help!I need criteria for AC corrosion!

• AC Safety:• NACE SP0177 – 15 Volts

• AC Corrosion:• European Standard CEN-EN 15280 – Almost done

• PRCI AC Corrosion Research (Elsyca/Corrpro/MetriCorr)

• NACE TG430 – Standard practice is under construction

Common AC Corrosion Thresholds

AC Current Density AC Corrosion Significance

Less than 2-3 A/Ft.2 (20-30 A/m2) No or Low Likelihood

3 – 10 A/Ft.2 (30-100 A/m2) Medium Likelihood

Greater than

10 A/Ft.2 (100 A/m2)

Very High Likelihood

Even in the Presence of Apparently Effective CP

Qualitative only! Nothing about rate of corrosion, which is what really counts! Right?

Factors that Influence AC Corrosion

Likelihood of AC corrosion can be determined by approximating the AC current density using Ohm’s Law:

where,

i = AC current density

VAC = AC voltage of pipeline to remote earth (which is where?)

ρ = soil resistivity (at holiday, not bulk soil – how do I measure?)

d = diameter of a circular holiday having an area equal to that of the actual holiday (million $ question!)

d

Vi

AC

ρπ

8=

Dangerous Equation! Use at your own risk!

Datalogging Equipment

Datalogging reveals conditions overlooked by instantaneous (“spot”) measurements

0

5

10

15

20

25

30

12:00 PM 6:00 PM 12:00 AM 6:00 AM 12:00 PM 6:00 PM 12:00 AM

AC

PIP

E-T

O-S

OIL

PO

TE

NTIA

L (V

olts)

AC Interference Modeling

• Soil Conditions

• Pipeline Characteristics

• Pipeline and Power System Alignments

• Power System Characteristics• Operating Voltage

• Fault Currents

• Phase Transpositions

• Tower Configurations

• Static Wire

• Grounding Design

• Counterpoise Data

• Substation Locations

AC Interference Modeling

• Computer Aided Predictive Modeling• CDEGS / Right-of-Way Software

• Accurate Predictions of Real-life Pipeline Phenomena

• Mitigation Designs Verified with Models

• Graphical and Text Output

• Design of Mitigation Systems• Innovative Grounding System Configurations

• Proven, Established Engineering Solutions

Modeling Output

RIGHT OF WAY SCHEMATIC

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 20 40 60 80 100 120 140 160

AC Circuit 3 - 115KV AC Circuit 7 - 500KV

AC Circuit 2 - 230KV AC Circuit 6 - 500KV

AC Circuit 1 - 500KV AC Circuit 5 - 115KV

Cypress Pipeline AC Circuit 4 - 230KVCrossings not shown for clarity

STEADY STATE PIPE TO EARTH VOLTAGE

15-Volt Maximum

0

30

60

90

120

0 20 40 60 80 100 120 140 160

CONSTRUCTION MILEPOST

VOLTS

No MitigationSingle Ribbon MitigationDouble Ribbon Mitigation

Safety During Construction

Safety Procedures

Safety Procedures

Safety: Testing

AC Mitigation & Control - What’s the Solution ? Parallel Mitigation, e.g. Zinc Ribbon(s) or Copper Cables(s)

MINIMUM MEASURESCP Personnel Safety – Dead-Front Test Stations

Design Tip:

Test heads can be designed & supplied with custom terminal ID labeling

Personnel SafetyEquipotential Gradient Control Mats at Test Stations

Test Station

Pipeline

Parallel Zinc Ribbon

7’x7’ Zinc Ribbon Mat “Spiral” – 8 inches below grade under well-drained gravel pad

Parallel Ribbon & Mat connected to pipe through DC-decoupler, a.k.a “PCR”

Solid-State DC Decouplers

Across Isolation Flanges Between Pipe & Zinc Ribbon or Copper Cable At Test Stations

Various Types & Ratings – Use The Appropriate Device For The Particular Application

Fence Grounding

AC Interference Quiz

1. Do you have AC concerns or problems?

2. What tools/technologies do you use to monitor for AC interference

and the effectiveness of your AC interference mitigation system?

3. Do you believe induced AC causes/increases corrosion?

4. How many of you use coupon technology for CP monitoring? For

AC interference monitoring? For DC interference monitoring?

5. If you are concerned about AC corrosion, is increasing the level of

CP a suitable solution?

Coupon Potential & Current Measurements

mAac/dc(+)(-)

PIPE COUPON REF.

Vac/dc

on / instant-off(+) (-)

AC Current Density

(A/sq.m or A/sq.ft) = Measured Current / Coupon

Surface Area

How Best to Detect/Monitor ACand DC Interference?

OR OR

Simple Coupon

Simple Electrical Resistance (ER) Corrosion Rate

Probe

Complete Monitoring System – Sophisticated

Technology but Straightforward to Use

Pipeline

MetriCorr Probe

Rod typeFlush type

Ref.Electrode

MetriCorr Logger with Remote

Monitoring Option

Corrosion rate

DC ‘On’ potential

DC IR compensated Potential

DC current density

AC potential

AC current density

Measuring is knowledge

Time-stamped, simultaneous data collection, as frequent as 1 set of readings (7 channels of data) every minute

Examples from the field:Moddest level of CP does protect, even under high AC

Evolution of Technology

Technology ReleaseProbe – 2004, Qty. = 2400Logger – 2005, Qty. = 750

M-Link RMU – 2010M-Report software/database - 2011

Unique, mature “fit for purpose” multi-channel

corrosion monitoring system based on multi-year industry

sponsored research

CONCLUSIONS – AC CORROSION

1. AC corrosion is real!

2. The mechanisms causing AC corrosion can be quite complex and are not completely understood, but proven, straightforward instrumentation to monitor the corrosion & the effectiveness of any mitigation does exist

3. AC corrosion can be controlled in part by optimizing CP levels – not too little, not too much, just enough

4. In the presence of AC, excessive CP or cathodic DC interference can increase corrosion rates dramatically

5. Instantaneous electrical measurements alone can be misleading

• Datalogging corrosion rate determines if there is a problem

• Concurrently logging various AC and DC electrical parameters determines the cause(s) of the problem and helps establish a suitable mitigation strategy

…Thank You Very Much

• QESTIONS???