Investigating Failure: Security Barrier with Compromised Corrosion Protection Welcome Speaker: Robert Ikenberry, California Engineering Contractors Organizers: Larson Electronics and JPCL Welcome Speaker: Rob Lanterman, KTA-Tator, Inc. Moderator: Josiah Lockley, Paintsquare Organizers: Paintsquare

Investigating Failure: Security Barrier with Compromised Corrosion Protection Agenda Rob Lanterman, KTA-Tator, Inc. (45 minutes) Questions and answers (about 10 minutes)

Recording Investigating Failure: Security Barrier with Compromised Corrosion Protection Recording and Reference This presentation is being recorded, and will be available soon by visiting www.paintsquare.com/webinars Copy of reference slides will also be available for download

Recording Recording Investigating Failure: Security Barrier with Compromised Corrosion Protection Today’s Speaker Rob Lanterman Coatings Consultant, KTA-Tator, Inc. A coatings consultant with KTA-Tator Inc. He is an SSPC Certified Protective Coatings Specialist and a NACE Level 2 Certified Coatings Inspector with over 10 years of coatings engineering experience

Presented by: Jayson L. Helsel, PE, PCS KTA-Tator, Inc. investigating FAILURE: Security barrier with compromised corrosion protection Presented by: Jayson L. Helsel, PE, PCS KTA-Tator, Inc.

Learning Objectives Comprehension of the webinar will enable the participant to: Understand the typical steps for conducting a coating failure investigation Describe some typical field coating tests or measurements when investigating a coating failure List some typical types of lab testing used for analyzing coating samples Understand the primary cause of the security fence failure

BACKGROUND Security barrier was installed at electrical power station Coating was failing after several months Facility within view of residential area

COATING FAILURE INVESTIGATION Data collection Field investigation Laboratory analysis Review, conclusions and report

Data Collection Specification Construction sequence Structure history Painting history

Specification Surface preparation Coating materials Film thicknesses Method of application Product data sheets

Construction Sequence Which components were erected first? Which components were erected last? How much time lapsed between the beginning and the end of a project?

Structure History How long has the existing system been in place? Have there been other failures? Were failures isolated or widespread?

Painting History Was the system or primer applied in the shop? Was the finish coat or entire system applied in the field?

Data collection Barrier constructed of galvanized sheet formed in corrugated shape Perimeter barrier was roughly rectangular

Data collection Primary surface preparation was degreasing Powder coating applied in fluidized bed process (i.e. shop applied) Low density polyethylene (LDPE) Field touch-up with acrylic primer/finish

Data collection Barrier installed in late fall Coating failure reported in following spring Failure worsened over year

Field investigation Patterns of failure (visual exam) Coating thickness Adhesion Substrate condition Sample collection

Looking for Patterns Is the system failing everywhere or in a single, isolated location? Directional exposure differences, e.g. south facing sun exposure

Looking for Patterns Failure/delamination from substrate along vertical edges Cut edges in majority of cases Field touch-up but poor coverage Often at inward bends Sometimes at vent openings Occurred on both sides, all exposures

Coating Thickness Gages for Different Surfaces Gages to measure thickness on ferrous and non-ferrous metal surfaces Micrometer measures thickness on disbonded coating chips Tooke gage measures thickness by observation into the coating system

Dry Film Thickness Gages Measuring over ferrous metal (Magnetic pull-off or magnetic flux) Measuring over non-ferrous metals like aluminum and copper (eddy current) Measuring over non-ferrous, non-metallic surfaces like concrete and wood (ultrasound)

Electronic/magnetic DFT gage

Micrometer

Tooke Gage

Coating thickness Electronic gage measured 10 to 55 mils Typical range 12 to 25 mils Thickness varied along panel Low end typically 12 to 15 mils High end typically 22 to 25 mils Higher thickness often at cut edge

Measuring Adhesion ASTM D3359 – Tape test ASTM D6677 – Knife adhesion

Measuring Adhesion by Tape Test ASTM D3359 Method A - The “X” cut (>5 mils) Method B - The “Cross-Cut” (< 5 mils)

Evaluating the X-Cut 5A No peeling or removal 4A Trace peeling along incisions 3A Jagged removal along incisions up to 1/16” on either side 2A Jagged removal along most of incisions up to 1/8” on either side 1A Removal from most of the area of the X under the tape 0A Removal beyond the area of the X

Measuring Adhesion by knife ASTM D6677 “X” cut Probe cut with knife to remove coating

Evaluating knife Cut 10 Coating extremely difficult to remove Fragments no larger than 1⁄32” by 1⁄32” removed with great difficulty 8 Coating difficult to remove Chips from 1⁄16” by 1⁄16” to 1⁄8” by 1⁄8” removed with difficulty

Evaluating knife Cut 6 Coating somewhat difficult to remove Chips from 1⁄8” by 1⁄8” to 1⁄4” by 1⁄4” removed with slight difficulty 4 Coating somewhat difficult to remove Chips in excess of 1⁄4” by 1⁄4” removed by exerting light pressure with the knife blade

Evaluating knife Cut 2 Coating easily removed Once started with knife blade coating can be grasped with ones fingers and easily peeled to a length of at least 1⁄4” 0 Coating easily peeled to length >¼”

knife Cut ADHESION 0 rating and poor adhesion near failing areas 4 to 6 rating and fair adhesion for intact coating when thickness was greater (e.g. 20 mils) 8 rating and good adhesion for intact coating when thickness was lower (e.g. 12 mils)

Substrate Condition Remove coating Determine presence of mill scale, rust or contamination Level of surface preparation (power tool cleaning, blast cleaning, etc.)

Substrate Condition No evidence of contamination Galvanized surface was smooth, no roughening obvious

Sample Collection Coating chips Corrosion samples Blister liquid/caps Failing & non-failing areas Corrosion samples Blister liquid/caps Coating retains

Laboratory Analysis Optical microscopy Infrared Spectroscopy Pyrolysis/Gas Chromatography/Mass Spectroscopy SEM/EDS

Optical Microscopy Visual examination of coating samples Cameras attached to the microscope May direct or alter the course of a failure investigation

Fourier Transform Infrared Spectroscopy Produces a fingerprint of coating Can determine if coating specified was the one actually applied

Pyrolysis/Gas Chromatography/ Mass Spectroscopy Detects presence of solvents trapped in a coating or in blister liquid

Scanning Electron Spectroscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDS) Uses magnification up to 10,000x Examines defects in the coating surface Compares failing and non-failing areas Provides an elemental analysis of the surface

Holiday Detection Two types: Low voltage (wetted sponge) – coatings that are less than 20 mils thick High voltage (spark testers) – coatings that are greater than 20 mils thick

Pinholes and Holidays Holidays – skips or misses in the coating/lining system Pinholes – tiny voids in the coating or lining Testing found many holidays

conclusions 80% of failure at cut ends of panels – allowed moisture to travel beneath coating Significant thickness variation – 12 to 25 mils Poorer adhesion at high thickness Failure at ends typically at higher thickness Numerous holidays at edges and openings

Repair RECOMMENDATIONS Remove poorly adhered coating Abrade/sand existing intact coating and exposed galvanizing Apply acrylic primer and 1 or 2 acrylic finish coats Consider an elastomeric acrylic coating

other RECOMMENDATIONS Simpler barrier design Better galvanizing surface prep Chemical cleaning Phosphate conversion coating Evaluate/improve application process to achieve uniform thickness Better field touch-up

Coating failure investigation Questions?

Recording Recording Investigating Failure: Security Barrier with Compromised Corrosion Protection Recording and Reference This presentation has been recorded, and will be available soon by visiting paintsquare.com/webinars Copy of reference slides available for download

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