welcome to 2018 western regional gas conference ir free...

Welcome to 2018 Western Regional Gas

Conference

IR FREE COUPONS – A

TECHNOLOGY REVIEW

◼ Presented by:

Jonathan Loomis,

CP Specialist &

Scott Smith, CP

Specialist

◼ Farwest Corrosion

IR FREE COUPONS – A

TECHNOLOGY REVIEW

◼ What’s Out There

◼ The Industry Buzz

◼ Typical Applications

◼ Conclusions

Comparison of CP Coupons & Soil

Corrosion Probes

CP Coupons Soil Corrosion Probes

Measure CP potential (-mV) using

reference electrodes

Measure corrosion rate with CP applied

(mils / yr.)

Used for “off” potential (e.g. minimum -

850 mV) or 100 mV polarization

criterion

Used as corrosion rate measurements as

an alternative to the CP potential

criterion

Buried pipelines where alternative CP

criteria (‘off” potentials, 100 mV

depolarization criterion) is used the

assess effectiveness of CP

Typically used for buried pipelines at

locations where potentials can not be

measured accurately or are not

dependable

Can be used for measuring high ‘off”

potential (> -1200 mV) to determine if

coating or pipe damage could occur

Can be used for congested plant piping,

under storage tanks, internal casings

What’s Out There

◼ IR Free Coupon

by MC Miller Co

◆ Double leads

◆ PVC Monitoring

tube

◆ 1.374 sq. in of

metal (8.862 sq.

cm)

What’s Out There

◼UC Underground

Coupon by EDI

⧫ Split Steel Coupon

⧫ 10 sq. cm surface

area

⧫ Inner backfill for

potentials through

split

What’s Out There

◼ Stelth 7

by Borin Mfg.

◆ Will not dry out in desert soil

◆ Local copper sulfate electrode to coupon

◆ Available in 1, 5, 10, up to 100 cm2 surface

area mild steel coupon

◆ 26 sq. in sensing surface

◆ Chloride ion trap

What’s Out There

◼ Fink Probe by

Cott Mfg.

◆ Steel Ring Coupon

◆ 0.01 sq. ft. (1.44 sq.

in) surface area

◆ Potential Access

Tube

◆ Jumper bond plugs

What’s Out There

▪ Farwest Hemi-10 & Dual Hemi-10

Steel Coupons

What’s Out There

▪ Farwest Flathead-10 & Cyclone-10

Steel Coupons

What’s Out There

◼ AC-10

Portable

Current

Density

Coupon /

Probe

◼ 10 cm²

size

◼ 25 mA =

25 A / m²

What’s Out

There

◼ Farwest

Rapid-

Check Test

Station

What’s Out There

◼ Typical

Test

Station

Wiring

What’s Out There

◼Wireless Coupon Test-Station

by OmniMetrix

◆ Dual coupons – 1 Native, 1 Polarized

◆ Automatically reads Native & I-Off,

followed by depol from 1-6 days

◆ Wireless to web

◆ 10-yr, field replaceable battery

What’s Out There

◼ Soil Corrosion

Rate Probes

◆ Various models /

different

measurement

methods, all require

an instrument for

measurement

⧫ ER, LPR, others

What’s Out There

◼ ER Probe ▪ LPR Probe

What’s Out There

◼DIP-1 & CSP-1

by Tinker & Rasor

◆ ER Probes measuring

mpy

◆ Measurement area 1

sq. in (6.5 sq. cm)

What’s Out There

◼Metal Samples

CT-10 ER Probe

Industry Buzz

◼ Paper 98666 - Presented in CORROSION ‘98

◆ THE USE OF IR DROP COUPONS AS A

PRACTICAL & EFFECTIVE TEST

METHOD

⧫ by Jeff Didas, Columbia Gas

(now at Matcor, Inc.)

Industry Buzz

◼ Paper 98666 – Major Points

◆ Locate anomalies (CIS Survey) then remediate, and only then locate IR Free coupons at location with:

⧫ Anomalies

⧫ High IR Drop

⧫ Poor / no coating

⧫ Most aggressive soils

Industry Buzz


◆ ICCP Pipe – IR Free Coupon Station Frequency:

⧫ No more than 5-mile spacing

◆ Galvanic CP Pipe – IR Free Coupon Station Frequency:

⧫ No more than 1-mile spacing

Industry Buzz

◼ Paper 05039 – Presented in CORROSION ‘05

◆ FIELD TESTS ON AN ADVANCED CATHODIC PROTECTION COUPON

⧫ by Frank J. Ansuini, Electrochemical Devices, Inc. & James R. Dimond, Dimondale Co., Inc.

Industry Buzz


◆ Excellent problem statement

⧫ IR Drop & Measurement errors

◆ References NACE Publication 35201 by TCC Task Group 210

◆ Gives arguments against other shapes (not flat)

◆ Centered sensing membrane eliminates the IR Drop of the first 5 cm where 90% of IR Drop can occur (Gummow)

Industry Buzz


SHAPE Tests IR Drop elimination during ON testing.

◆Rod shaped coupon-disconnect potentials still contain

residual voltage drop error in the presence of a current

field.

◆Concentric CP coupons during ON testing have minor

(2-10 mV) voltage drop error

⧫ Disconnecting coupon or interrupting rectifier will

substantially eliminate error when necessary

Industry Buzz


Soil Resistivity Effects on Coupon Potential Measurements

◆ 90% IR Drop error eliminated in high resistivity environments

◆Virtually all IR Drop error eliminated in low resistivity environments

Industry Buzz


Effects of Distance from Pipeline

◆ No effect of distance on the amount of error

eliminated but there was a distance effect in

the actual potential reported

Industry Buzz


Coupon orientation contained error, mV (%) (from fixed 300 mV surface error)

◆ Facing structure, back to anode 35mv (12%)

◆ Perpendicular to structure and anode 56mv (19%)

◆ Back to structure, facing anode 67mv (22%)

Industry Buzz

◼ Paper 07037 - Presented in CORROSION ‘07

Use of CP Coupons and Soil Corrosion Probes

in Application of Pipeline Cathodic

Protection Criteria

⧫ By Naeem A. Khan, Saudi Aramco

Industry Buzz


Introduces “new” ISO/FDIS 15589-11, lists different CP

potential criteria for various soil resistivities.

◆ Both coupons and probes can be used to implement

corrosion control monitoring program

⧫ Coupons -> polarized potentials

⧫ SCPs (Soil Corrosion Probes) ->where polarization

insufficient, but where corrosion rate measurements

indicate effective protection on the structure

◼ (RP-0104-2004) -use of CP coupons for CP potential

measurements

Industry Buzz


ISO/FDIS 15589-1:2003 CP PROTECTION CRITERIA

◼ Soil Type Soil ResistivityProtection Potential

◼ Aerobic <100 ohm-m -850

100 to 1000 -750

>1000 ohm-m -650

◼ Anaerobic conditions -950

Industry Buzz


◼ NACE Committee TG-321 finalizing Technical Report on SCRPs (Soil Corrosion Rate Probes) mainly addresses applications for ER SCRPs on buried pipelines.

◆ Also includes information on Linear Polarization Resistance (LPR) probes used for assessing soil corrosiveness, and the use of corrosion probes for reinforced concrete structures.

◆ SCRPs typically used on buried or congested piping, where CP potentials cannot be reliably measured and corrosion rate measurements using ER probes are used as an alternative to conventional CP criteria for buried pipelines.

Industry Buzz


◼ CP Coupons

◆ Measure CP Potential (-mV) using CSE’s

◆ Used for “OFF” or 100 mV criterion

◆ Also used for measuring high (>-1200 mV) “OFF”

potential for coating or pipe damage evaluation

Industry Buzz


◼ SCRP (Soil Corrosion Rate Probes)

◆ Corrosion rate with CP applied (mils/year)

◆ Used as an alternative to the CP potential criterion

◆ Typically used at locations where potentials cannot be

measured accurately or are not dependable

◆ Can also be used for congested plant piping or under

storage tanks

Industry Buzz

◼ RP0104-04

The Use of Coupons for Cathodic Protection

Monitoring Applications

◼ Depol testing without interrupting rectifiers

◼ May be differences between polarized pipe & coupon P/S

◼ High IR Drop locations can cause stray current corrosion

on coupons

Typical Applications

◼ Stray Current – Static (Pipeline)

◼ Stray Current – Dynamic (Light Rail)

◼ Induced A.C.

◼ Distributed Anodes

◼ Congested Right-of-Way

◼ Shorted Casings

Stray Current DC – Foreign Pipeline

Foreign

Pipe

Protected

Pipe

Voltage Gradients

Around the

Protected Pipe

Interference Current

DischargeInterference

Current

Pickup

PROFILE VIEW

+ -Rectifier

Impressed Current

Groundbed Remote from

Foreign Pipe

Interference

Current

Pickup

Foreign

Pipe

Protected

Pipe

Voltage Gradients

Around the

Protected Pipe

Interference Current

DischargeInterference

Current

Pickup

PROFILE VIEW

+ -Rectifier

Impressed Current

Groundbed Remote from

Foreign Pipe

Interference

Current

Pickup

◼ Cathodic Interference

Stray Current DC – Foreign Pipeline

◼ Anodic Interference

Foreign

Pipe

Impressed

Current

Groundbed

Voltage Gradients

Around the

Groundbed

Interference

Current

Discharge

Interference

Current

Discharge

Interference

Current Pickup

TOP VIEW

- +Rectifier

Protected

Pipeline

Remote from

Foreign Pipe

Foreign

Pipe

Impressed

Current

Groundbed

Voltage Gradients

Around the

Groundbed

Interference

Current

Discharge

Interference

Current

Discharge

Interference

Current Pickup

TOP VIEW

- +Rectifier

Protected

Pipeline

Remote from

Foreign Pipe

Transit

Systems – DC

Traction

◼ Stray DC Interference (dynamic)

800 VDC

+

-

Up to 3,000 A

Stray Current DCdc

sub-station

ground

pick-up

IsIs

IL

Ie

IR

Ie

Is

discharge

metallic structure(e.g. watermain)

runningrails

O/H power conductor

▪ Pipe-to-soil potential shifts are dynamic

▪ Does short duration allow time for polarization decay?

Induced AC

▪ No Corrosion Expected iac < 20 A/m2

▪ Corrosion Unpredictable 20 A/m2 < iac < 100 A/m2

▪ Corrosion Expected iac > 100 A/m2

I2

I1

Induced AC Interference

AC Current Density:

I Density = 8*VAC /dρπ

d = diameter of holiday

ρ = soil resistivity (ohm-cm³)

Distributed Anodes (Directly Connected)

Potential Shielding – Multiple Lines in

R-O-W

• Multiple Rectifiers

• Cross Bonds

• Coating Condition

• Anodic Interference

• Cathodic Interference

Monitoring Internal Corrosion –

Shorted Casings

◼ If a pipeline is in a casing within an HCA, it must be

assessed according to 192.921 (a) (1-3) – approved

methods are ILI, direct assessment, pressure test,

“other technology” such as guided wave

Monitoring Internal Corrosion –

Shorted Casings

Monitoring Internal Corrosion – Shorted

Casings

CorrTalk® RMU1-ER

Remote Monitor

Metal Samples CT-10 ER

Probe

Conclusions

◼ CP coupons & ER probes can be used as an

alternative to pipeline potential measurements in

determining CP effectiveness.

◼ CP coupons are useful to measure polarized /

depolarized potentials on pipelines influenced by

foreign CP systems or where an operator’s CP

systems can not be simultaneously interrupted.

Conclusions

◼ ER Probes can be used where required

polarization can not be achieved or measured

accurately, but can show effective protection

through corrosion rate measurements.

◼ Know your situation & pick the tool.

◼ An inexpensive tool can save years of headaches.

Thank You!

welcome to 2018 western regional gas conference ir free...

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