Innovative NDE Applications for Corrosion Evaluation of Oil and Refining Assets

by Mike Nugent, The Equity Engineering Group, Inc.

Mike Nugent E2G Logo

• 30 Years Refining/Petrochemical and Utility Power Generation experience. Professor at Stevens Institute of Technology School of Engineering and Science.

Principal Materials Engineer with ConocoPhillips, Tosco, Exxon and Con Edison

Active member NACE STG 34. Member API Sub Committee on Materials and Corrosion (Refining Group)

Fellow ASNT

Current job

Mike has been involved with materials and corrosion problems in the refining and chemical process industries and power generation systems. For the last 2 years, he has worked for as a consultant to refineries, chemical plants and utilities throughout North America, primarily in the areas of Corrosion, Non-Destructive Testing, Risk-Based Inspection and Fitness-For-Service.

Presentation Highlights

Overview of some Damage Mechanisms

Mostly Localized Damage modes

Existing Technology to characterize/monitor damage

Applications are on-line and non-intrusive

Industries

Primarily Oil Refining

Other uses in Oil Production, Transportation

Uses in Utility distribution applications

Refining & Petrochemical $1.7 B

Corrosion Damage Accounts for the cost of one Major Facility Annually

Pipeline ,Oil/Gas Production $8 B

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Motivation for Focused Mechanical Integrity Program

• A large percent of the total asset risk is concentrated in a small percent of the equipment items

• There are limited resources to maintain equipment

• Cost incentive to improve reliability• Data Information Knowledge Decision

Asset Mechanical Integrity Paradigm

• Data Accurate, repeatable and in a format useable by necessary team members

• Information Damage mechanism model for specific component under review

• Knowledge Of operational variables and mechanical integrity criteria

• Decision For safe, reliable, economic performance of asset

Industry Needs Methodology to Manage Asset Integrity

• Any Incident adversely that impacts environment affect entire industry

• Assets are aging and increasing in severity of operation

• Acquisition of numerous points of data alone does not insure integrity

• Industry evolving Mechanical Integrity Methodology in response to optimize resources (Risk Based Approach)

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Reducing Equipment Risk through Inspection

• The risk defined by an individual piece of equipment can be changed by altering inspection:– Inspection Frequency– Inspection Scope – Type and Area Coverage– Improved Tools/Techniques – Practices – Shift to Focused External In-Service

and Continuous Inspection to reduce risk and minimize out-of-service internal inspections

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Management of Risk using RBIR

ISK

LEVEL OF INSPECTION ACTIVITY

Uninspectable risk

Risk with typical inspection program

Risk using RBI

API RBI 581 Formalizes Approach

Consequence

Like

lihoo

d

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Qualitative Risk-based Ranking Matrix

LIK

ELIH

OO

D C

ATEG

ORY

CONSEQUENCE CATEGORYA B C D E

5

4

3

2

1

HigherRisk

MediumRisk

LowerRisk

Medium-HighRisk

Different Approaches use Similar Data Gathering and Assessment Tools

• A variety of Mechanical Integrity RBI programs utilize enhanced NDE technologies approaches

• Must be appropriate for specific damage mechanism

• Must be accurate, repeatable and responsive• One Specific Operating Unit examples will be

discussed in detail, other mechanisms will be presented in less equipment specific detail

Typical Refinery Amine Unit

Wet H2S Cracking Suspect Areas Treated

Gas

KO P

ot

Treated Liquid Hydrocarbon

Sour Liquid

Sour Gas

To Fuel Gas

Heat Stable

Salt Removal System

Contaminants

Regenerated Amine

Slip Stream

Flash Valve

Sour Water Purge

To Sour Water

Stripper

To H2S to Sulfur

Recovery

Amine Regenerator

Liquid Absorber

Gas Absorber

Lean/Rich Exchanger

Typical Amine Unit used in Refinery H2S removal processing

Internal Inspection and Initial Evaluation

Visual internal inspection identified suspect Hydrogen Blistering

Penetrant Inspection verified sub-surface possibility (depth)

CONDITIONS REQUIRED Liquid Water (free and

condensed) H2S > 50 ppm in liquid

water Susceptible Materials:

CS, 405 SS, 410SSAGRAVATING FACTORS Dirty Steel HSS, Chlorides, Cyanides Low pH (= / < 5.5) Lack of PWHT & High Hardness

MORPHOLOGY OF DAMAGE Hydrogen blisters: ID/OD Bulges in the

steel of pressure vessels

HIC: Associated to blistering or laminations.

SOHIC and SSC: Associated with the welds. SSC found at zones of high hardness

Wet H2S Cracking Damage Mechanism

INSPECTION WFMT, ACFM, RT applicable NDTs PT not effective (cannot find tight

cracks) SWUT good volumetric NDT AET is an option for crack growing.

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Hydrogen Blistering• Formation of sub-surface planer cavities in steel (non-metallic inclusion)• Atomic hydrogen (generated from corrosion) diffuses into steel and forms blister in void• The growth of near surface blisters produce bulges in metal

Cracking related to corrosivity of amine•Hydrogen Induced Cracking (HIC)

• A “step-wise” internal cracking connecting adjacent blisters of different planes together.• Driving force is the increasing molecular hydrogen pressure of the adjacent hydrogen blisters at their boundaries

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•Stacked set or “array” of hydrogen blisters• A “vertical stack of cracks”• Joined together by HIC• In the through wall thickness direction (perpendicular to stress)• Result of high tensile stress• Typically in a high hardness carbon steel• Commonly found associated with welds

Stress Oriented Hydrogen Induced Cracking(SOHIC)

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• C - Scan - Top Left

• B- Scan - Bottom Left

• Volumetric View - Top Right

Automated Ultrasonic Mapping can be done with Equipment in Service

Other Damage Mechanisms

• Innovative NDE applications provide in-service capabilities of monitoring

• Advanced technology places more powerful analytical tools in inspectors hands

• Selected Damage mechanisms found in Oil and Gas production and Refining will be shown along with Advanced Monitoring Techniques

Corrosion Under Insulation/Fireproofing

• Insulation/Fireproofing can accumulate moisture and causeaccelerated corrosion of Carbon Steel equipment and supports

• Breaches of weather jacketing increases with age andmechanical damage. Coatings, if applied on initial constructionmay deteriorate with age

• Extensive stripping and abatement needed for VT and UT forAPI 570 Inspections

• CR/DR can give general condition an specific thickness inrecordable format without initial insulation removal/abatement

• CR/DR can provide measurable, reviewable information foradditional prioritization of equipment inspection/repair

Digital Radiography• DXR replaces conventional

film radiography • DXR is real-time and can

be applied to motion acquisition

• Saves significant time in work flow; Non-contact

• DXR data can be stored electronically

• Wall thickness measurements possible by density or pixel counting

• Newer DXR panels are 4 MP, 16” x 16”, 3 FPS, 13 lbs and faster than film by 10x

Immediate Assessment of CUI Equipment

Level Bridal after Insulation Removed

CR/DR can produce measurable image with insulation in-place

Phased Array Brings more Analytical Capability to Field

PA more powerful and portable for field applications

Images can be recorded for more detailed analysis

Hydrofluoric Acid (HF) Alky Flange Face Corrosion Assessment

• HF will cause localized corrosion on raised faces of pipe andequipment flanges

• Tenacious HF and stringent PPE requirements make typicaldisassembly and inspection challenging

• HF Unit Flange Integrity must be assessed per API 751• Manual flange opening and inspection nearly as costly as

outright replacement• Phased Array-UT can significantly enhance detection and

sizing of flange face corrosion damage for replacementprioritization for turnaround

• Proven to be accurate and cost effective over conventionalinspection methodologies

HF Flange showing scale and corrosion under scale

Ring Joint Flange Cracking

• Ring Joint Flanges (RJF) have been used on many high Pressure piping components

• Ring Joint flanges have had significant cracking from mechanical and Stress Corrosion Cracking

• Typically discovered by PT or manual UT after flanges have been opened during Turnaround

• Discovery during TA may extend unit downtime due to lack of component availability

• PA-UT significantly enhances detection and sizing of corrosion damage while vessel is in service or just off line to allow for repair/replace planning

Typical FEA model and Cracking in RJF

Mat Type UT Array Technology

• Installed UT arrays proven for installed sensors up to 500 F

• Installation in difficult to access areas result in maintenance savings

• Continuous readings yield risk mitigation through continuous monitoring

Injection/Mix Point Corrosion Monitoring

• Injection/Mix point corrosion has been responsible formany serious refinery incidents

• API 570 specifies inspection guidelines and NACE IP34101 provides specific process guidelines to minimizeinjection point damage

• Spot UT and RT provide static monitoring of potentialdamage areas

• Installed UT Array can provide dynamic monitoring ofsuspected injection point damage locations withoutrepeated access mobilizations

Injection Point Failures are a Significant Event

Crude Overhead Corrosion Monitoring• Crude Unit Overhead with Chemical Injection and/or

Water Washes are subject to periodic inspections per API570

• Many overhead lines have no platform access makingthese inspections difficult and costly

• UT and RT can provide useful inspection data, but costlyto obtained if crane access/scaffolding required

• Installed UT Array can be installed and accessed on acontinuous basis to improve operational knowledge

Sand Erosion Offshore Risers Monitoring

• Sand Erosion can occur at change indirection/diameter in offshore production risers dueto solids ingestion. This erosion is typified by asmooth surface with a sand dune pattern

• Riser locations where sand erosion may occur aredifficult to access and inspect with conventional UT orRT

• UT array permanent mounted sensors can be appliedto suspect areas for accurate monitoring without theneed for manual access

Reactor Effluent Air Cooler Piping Erosion

• Reactor Effluent Air Coolers have suffered numerous Erosion - Corrosion incidents due to ammonium Bi-sulfide and Ammonium Chloride Erosion

• Rigorous monitoring of operating conditions must be followed by extensive UT and RT surveys

• On-line Mat UT Array installed sensors allow continuous or intermittent monitoring of suspect areas

Combination of Innovative Inspection Techniques along with

RBI Approach Yields Positive Results

• Focused inspections target problem areas• Look to focus on higher risk equipment• Application of innovative inspection yields

results

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Historical results Oil Refinery - Pressure Vessels

2008 without inspection 2008 with inspection

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Coordinated RBI Program with Innovative Asset Evaluation Summary

• Identify in an Quantative basis your High Risk Equipment

• Focus resources on that equipment to reduce overall Equipment Risk

• In-service inspections can be cost effectively planned to minimize cost and service interruption

• Installed sensors realize maximum access cost reduction and provide risk reduction through continuous monitoring

Questions???

Michael NugentPrincipal Engineermjnugent@equityeng.comThe Equity Engineering Group, Inc.PO Box 912Westwood, NJ 07675Mobile: 1-201-446-6693

Smart Technology for Aging Infrastructure

www.equityeng.com