dot pipeline corrosion

7/27/2019 DOT Pipeline Corrosion

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ABC Chemical Complex 1

Corrosion Control

and Monitoring

ABC Company

ABC Chemical ComplexEngineering Specification




Corrosion Control & Monitoring

SCOPE

– This Engineering Specification includes

external and internal corrosion control and

monitoring for DOT regulated pipelines.

– Design, construction, construction inspection,

construction acceptance, operation, and

maintenance of DOT regulated pipelines arecovered by this Engineering Specification.




Corrosion Control &Monitoring

GENERAL

– All DOT regulated ABC pipelines require

protection from the environment.

– Corrosive elements in the pipeline stream must

be neutralized or the pipe material must be

resistant to the stream.





Minimum requirements for corrosion

control:

– External Corrosion Control

» Buried DOT regulated pipelines will be coated and

cathodically protected

– Internal Corrosion Control

» Known corrosion rate based on historical data» Corrosion rate from a national standard data base

» Data collected from laboratory prototype testing





Minimum requirements for corrosion

control (Continued):

– Above Ground External Corrosion Control

» Coat with an approved system with resistance to the

soil and internal fluid temperature





REFERENCES

– NACE RP 0169-92

– Surface Preparation:» NACE No. 1, SSPC-SP 5, White Metal Blast

Cleaning

» NACE No. 2, SSPC-SP 10, Near White Metal Blast

» NACE No. 3, SSPC-SP6, Commercial Blast» NACE No. 4, SSPC-SP 7, Brush-Off Blast


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PERSONNEL REQUIREMENTS

– Engineering design will be performed by a

Corrosion Engineer with training and

experience in the proposed corrosion control

system.

– Coating, lining, and painting inspection will be

performed by an inspector with appropriatetraining and experience.




PERSONNEL REQUIREMENTS (Cont..)

– Cathodic protection installations will be

inspected by an inspector with training and

experience in cathodic protection inspection.

– Internal corrosion monitoring installations will

be inspected by an inspector with training and

experience in internal corrosion monitoringinspection.




DESIGN REQUIREMENTS, EXTERNAL

– Cathodic Protection Criteria

» Buried Onshore Pipelines: Pipe-to-soil potential

equal to or more negative than -0.85 volts

referenced to copper-copper sulfate electrode and

recorded immediately after current interruption

(Instant-off potential).

» Offshore Pipelines: Pipe-to-water potential equal toor more negative than -0.80 volts referenced to a

silver-silver chloride electrode with “instant off”

potential reading.




» Tank Bottoms: Steel-to-soil potential equal to or

more negative than -0.85 volts with a copper-copper

sulfate half cell and “instant off” potential.

» Maximum pipeline potential: Equal to or less than -1.5 volts to a standard copper-copper sulfate half

cell with the current temporarily interrupted.




– Coating Requirements

» New buried pipe sections shall be coated with one of

the following types:

Fusion bonded epoxy Coal tar epoxy

Polyolefin tape

Prefabricated films

Other coating systems approved by Central Engineering

» Surface preparation shall be in accordance with

manufacturer’s recommendation and Appendix B.




Methods Used for Cathodic Protection

– Galvanic Anode Systems

» Provide protection to the structure by the potential

difference generated by the electrochemical reaction

between the structure and the anode through a soil

or water electrolyte.

» Typically used in soil or water with resistivity less

than 5000 ohm-cm.




– Methods Used For Cathodic Protection (Cont)

» Impressed Current Systems

Uses external source of DC power, usually an AC trans-

former with an AC to DC rectifier, to provide the drivingvoltage to the structure to be protected.

Potential difference between the anode and the structure

creates current flow from the anode into the soil and onto

the pipeline.

Used when the soil resistivity exceeds 5000 ohm-cmand/or more than 5 amperes of impressed current are

required.





– Equipment

» Galvanic Anode Systems

Anode: Magnesium onshore, Galvalum III offshore.

Junction box to connect leads from structure and anode.» Impressed Current Systems

DC transformer/rectifier (supplied as a unit).

Anode(s) with inert or low reactivity characteristics.

Terminal box with resistors to adjust current flow to eachanode or anode string.





– Miscellaneous

» Install lightning arrestors.

» Provide electrical isolation: Insulating flanges or

spools.» Minimize interference with bonding stations.

» Install test stations to measure potentials.

» Complete the following documentation:

Bonding and/or anode bed data sheet.

Bonding station data sheet.

Test station data sheet.





– Impact on Operating Equipment

» Apply NEMA electrical-class safety requirements to

all equipment associated with impressed current

installations.» Install CP equipment in areas not requiring

intrinsically safe design.

» Locate anode beds to minimize effect on other

structures and to minimize mechanical damage fromforeign construction.





» Perform interference testing on all equipment that

may be damaged by the new CP installation.

Testing shall include, but is not limited to, the

following situations:

Pipelines crossing within 5 feet.

Metal Structures within 5 feet of the pipeline.

Metal Structures within 200 feet of the anode bed.





– Impact on Operating Equipment

» Design CP systems with capacity for current loss

through interference bonds and future current loss

due to coating deterioration.» Minimize casing installations for protection of the

carrier pipe. Perform interference testing as shown

in Company Corrosion Control & Monitoring

Specification Appendix E. Provide bonding stations

for each casing installation.





DESIGN REQUIREMENTS, INTERNAL

– Corrosive chemicals in the pipeline stream

» May reduce stream (liquid or gas) quality or

» Cause general thinning or pitting attack

» Shall be handled by one of the following methods:

Neutralization or removal of the corrosive chemicals.

Select a pipe material which is resistant.

Coat the internal surfaces of the pipe.





– Design package will contain:

» Provisions for upset/emergency conditions.

» Recommended corrosion monitoring program.

» Recommended corrosion monitoring equipment.

» Installation of personnel safety devices and

platforms required for safe performance of duties.

» Pigging procedure when pigging facilities are

included in the design package.

» Compliance with regulations of local, state, and

federal jurisdiction for pigging procedures.





– Documentation Requirements

» Determine thickness measurement locations

(TML’s) based on the most probable locations for

corrosion or erosion-corrosion damage. SelectTML’s with the assistance of the Corrosion

Engineer.

» Collect baseline thickness readings on all new

installations.

» Install corrosion monitoring equipment where the

“worst case” corrosion attack is expected.

» Provide corrosion monitoring data sheets.





DESIGN REQUIREMENTS, ABOVE

GROUND EXTERNAL

– Coat with a coating system that is recom-

mended for the environment.

– Prepare surface in accordance with external-

coating-system manufacturer’s

recommendations. See Company CorrosionControl & Monitoring Specification Appendix

B.





INSTALLATION

– Quality Control, External Systems

» Coatings

Qualified Inspector presence - 100%.

Field applied coating systems - 100% inspection.

Shop applied coating systems - 100% inspection.

Coating repairs - 100% inspection.

Protect all stored coating materials at the construction sitefrom weather, particularly directly sunlight and heat.





» Pad in the pipe trench

Inspect just prior to laying the pipe in the trench.

Remove all trash and construction debris.

» Cables

Inspect upon receipt at job site to detect nicks and damage.

100% inspection at the mill with proper mill cert..

Avoid damaging cable insulation during installation.

Splice cables aboveground in terminal boxes.

Use non-conductive conduits for cable installation.

Make cathode cable connections aboveground, if possible.

Repair buried connection in accordance with the original

coating manufacturer’s recommendations.





– Transformer/Rectifier Systems

» Install by a qualified electrician.

» Test rectifier at maximum design load to assure the

DC output meets the manufacturer’s specificationsincluding the maximum AC ripple.

» Calculate rectifier efficiency and record on the

rectifier data sheet.

» Verify the positive cable is attached to the anode bed and the negative cable is attached to the

protected structure or pipe.





» Miscellaneous Considerations

Inspect cables in terminal boxes to assure correct labels.

Verify test stations, bonding stations, and associated

hardware for cathodic protection service.

Contact owners/operators of foreign pipelines to enable

testing before and after new cathodic protection project

commissioning.

Record base readings on the new pipeline or structure

prior to cathodic protection system energizing. Record

potentials at all interference bonds and test stations.

Energize system in small current increments and record

potentials with each increase until protection is achieved.

Check bonding stations for interference problems.

File all commissioning data in the original equipment file.





– Quality Control Requirements, Internal Surface

» Inspect corrosion monitoring installations with the

services of a qualified Corrosion Technician.

» Take baseline data prior to pipeline commissioning.» Install lined pipelines per design.

» Repair lining of field joints as recommended.

» Install corrosion monitoring devices per design.

» Complete electrical installations with qualified

electricians.

» Document commissioning information as a part of

the original equipment file.





– Quality Control Requirements, Internal Surface

» Delay work initiation pending review of design

package by coating inspector.

» Protect coating material from weather.» Prepare surface for coating per manufacturer’s

recommendation immediately before coating

installation.

» Follow manufacturer’s recommendation for dew point and humidity.





OPERATIONS

– Perform cathodic protection surveys annually in

accordance with Company CP procedure.

– Monitor bonding and test stations annually.

– Read and record rectifier output monthly with

changes reported to the SR. Inspector for

evaluation and action. – Correct deficiencies in a timely manner.





MAINTENANCE

– Test rectifier stacks for proper performance

annually.

– Check anode bed resistance annually.

– Check insulating flanges and spools annually.

– Document all maintenance tests and add to the

equipment file.

C i C t l & M it i



ABC Ch i l C l 31


Appendices

A - Coating Reference Index

B - Surface Preparation

C - Sample Data Sheets» Rectifier Data Sheet

» Anode Bed Data Sheet

» Galvanic Anode Data Sheet

» Potential Survey Data Sheet

Predesign Testing

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