Attachment_B_-_Airport_Tank_Final_Inspection_Report.pdf
PDF 6 MB Posted
- Attached to
- Airport Reservoir Rehabilitation Project
- Solicitation number
- WA-26-14826
- Issued by
- Santa Cruz County, California
About this file
This is a Final Maintenance Inspection Report prepared by CSI Services, Inc. for the City of Watsonville's Water Operations Division regarding the Airport Tank located at 29 Emme Lane, Freedom, California. The inspection, conducted on March 27, 2019, assessed the condition of the existing coatings and structural integrity of the welded steel tank, which is approximately 150 feet in diameter, 30 feet in height, with a nominal capacity of 3 million gallons. The tank was built in the late 1980s to early 1990s by San Luis Tank of Paso Robles and features a pitched roof with knuckle radius, three plate courses, one center roof vent, two manways, interior and exterior ladders, and a cathodic protection system. The inspection involved visual observations and testing procedures including photographs, video documentation, rust grade evaluation per ASTM D610, corrosion grade assessment, paint chalking analysis per ASTM D4214, coating adhesion testing per ASTM D3359, and blistering evaluation per ASTM D714.
The exterior alkyd paint system was rated in good overall condition with heavy chalking (ASTM D4214, No. 6) and minimal corrosion (less than 0.03 percent of total surface area), with paint dry film thickness of 10-11 mils on the roof and 7-8 mils on the shell. The interior epoxy lining, approximately 35 years old, was found in fair condition with widespread cracked blisters below the highest water level and isolated areas of corrosion above it, though no significant metal loss was detected due to the cathodic protection system's operation. The report recommends immediate spot repair of the corroding center roof vent flange, reinspection in 3 to 5 years as part of normal maintenance cycling per AWWA standards, and eventual relining of the entire tank soon after, with consideration given to relocating interior tank bottom piping from the floor to the shell as part of future large-scale maintenance work.
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Attachment B – Airport Tank Inspection Report
P. O. Box 801357, Santa Clarita, CA 91380 877.274.2422
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Prepared for:
Beau Kayser Water Operations Division City of Watsonville P.O. Box 50000 Watsonville, CA 95077-5000
Prepared by:
CSI Services, Inc.
Patrick Sweeney Project Manager June 12, 2019
Hawaiian Office: P.O. Box 671, Aiea, HI 96701 Northern California Office: P.O. Box 371, Sonoma, CA 95476
Coating Specialists and Inspection Services, Inc.
Consulting Evaluations Tank Diving Inspection
Final Report - Maintenance Inspection Airport Tank
City of Watsonville Page i
Hawaiian Office: P.O. Box 671, Aiea, HI 96701 Northern California Office: P.O. Box 371, Sonoma, CA 95476
Coating Specialists and Inspection Services, Inc.
Consulting Evaluations Tank Diving Inspection
Table of Contents
Introduction ..……………………………..………….………… Page 1
Summary….........……………………...………..…….…...…… Page 1
Background........……………………...………..…….…...…… Page 2
Field Evaluation ……………………...………..…….…...…… Page 2
Discussion…..…………………………………………..……… Page 5
Recommendations………………………….....….……...…… Page 7
Attachments
- Field Notes
- Exterior Photos
- Interior Photos
- CSI Chart 1 – General Description of Conditions
- CSI Chart 2 – Rust Grade Criteria
- CSI Chart 3 – Corrosion Grade Criteria
- CSI Chart 4 – Coating Chalking Criteria
- CSI Chart 5 – Coating Adhesion Criteria
- CSI Chart 6 – Coating Blistering Criteria
- DVD
City of Watsonville
June 12, 2019
Introduction
City of Watsonville authorized CSI Services, Inc. (CSI) to conduct a maintenance inspection on Airport Tank located at 29 Emme Lane, Freedom, CA. This report documents the findings of the inspection and services performed. Any recommendations have been made in accordance with the applicable requirements of American Water Works Association's Standard (AWWA) D102 "Coating Steel Water Storage Tanks," AWWA Standard M42 "Steel Water Storage Tanks," and CSI's experience with evaluating hundreds of water storage facilities. A photo summary and narrated DVD video are also included to document the condition of the tank.
The field-work was completed on March 27, 2019 by a team primarily comprised of Steve Metcalf, Anthony Braschler and Justin Sweeney. The exterior shell observations were made mostly from grade level, while the exterior of the roof was examined close-
up. The interior inspection was carried out with the tank’s water level at approximately 24 feet using special underwater diving equipment and techniques. Steve Metcalf was the site supervisor and Anthony Braschler was the lead diver. Mr. Pat Sweeney, Project Manager reviewed the results of the field data and prepared recommendations for maintenance work. Mr. Sweeney is a certified Level 3 inspector through both SSPC and NACE, an SSPC Certified Protective Coating Specialist, and has evaluated over a thousand storage tanks.
Summary
The exterior paint system is heavily chalked, relatively thick, and in generally satisfactory condition. Although the paint can spot repaired and overcoated anytime for aesthetics, the only immediate need for paint work is at the center roof vent. The flange to the vent has significant corrosion, up to an including some metal loss and should be spot repaired.
Overall the interior linings were found to be in a condition expected of a thin film epoxy that is approximately 35 years old. The area above highest water level (HWL) has areas of corrosion and peeling lining, while the lining below the HWL has widespread cracked blisters and isolated rust. The lining system is nearing the end of its expected service life. However, since there are no areas with significant metal loss from corrosion, it is projected that relining of the tank can be deferred for perhaps up to 5 years. On this basis, it is recommended that the tank be placed back on a normal 3 to 5 years maintenance inspection cycle as recommended by AWWA with an eye on relining the tank soon after.
June 12, 2019
Background
The Airport Tank is a welded steel, above ground reservoir built by San Luis Tank of Paso Robles, CA. Year of construction was not legible on the tank name plate, but it is suspected that the tank was built in the late 1980's to early 1990's. The tank is approximately 150 feet in diameter by approximately 30 feet in height, providing a nominal capacity of 3 million gallons. It is the only tank on the site and is adjacent to Burchell Avenue. The tank shell has three plate courses that are connected to a pitched roof by a knuckle radius. The roof plates are supported internally by a structure consisting of rafters, ringer girder, and a center column. The tank has one center roof vent and two manways. The overflow pipe and all tank piping enter the tank through the tank floor. The outlet of the overflow pipe has not identified during the inspection. There is one interior ladder and one exterior ladder, each leading to the single roof access hatch. The exterior ladder has a fall prevention gage and vandal deterrent, and the roof access is surrounded by a roof railing system. The tank rests on a concrete ringwall with no anchor bolts and there is a cathodic protection (CP) system installed within the tank.
It is believed that the tank coatings are the original coatings applied and that no substantial maintenance coating activities have been completed. All of the interior steel surfaces, including the roof, shell, tank bottom, and appurtenances are coated with a thin film epoxy lining. The interior roof lap seams are not caulked. The exterior of the structure is painted with what appears to be an alkyd paint system.
Field Evaluation
The purpose of this survey was to assess the condition of the existing coatings and recommend maintenance coating work, where needed. The evaluation mainly involved visual observations, but also involves various testing procedures. Photographs and video were taken to document the field inspections, and a photo summary and narrated DVD is included with this narrative report. For survey purposes, the tank has been segmented into defined areas: exterior roof, exterior shell, interior roof, interior shell, and interior floor. The various appurtenances within each of these areas have also been evaluated. A rating system has been developed to quantify the condition of these various tank areas. Each of the rating criteria is found in the Attachments (Charts 1 through 6).
The condition of the coating systems was rated as being poor, fair, good, or excellent (Chart 1). The extent of any rust defects identified within each of the areas was generally determined using the guidelines set forth in ASTM D610 “Standard Test Method for Evaluating the Degree of Rusting of Painted Steel Surfaces” (Chart 2).
Where applicable, the characteristic or stage of corrosion was determined in accordance with CSI Corrosion Grade criteria (Chart 3). The degree of paint chalking was determined in accordance with ASTM D4214 “Standard Test Method for Evaluating the Degree of Chalking of Exterior Paint Films,” Test Method D659, Method C (Chart 4).
Coating adhesion was assessed in accordance with ASTM D3359 “Standard Test Method for Evaluating Adhesion by Tape Test, modified Method A and/or a modified version of ASTM D6677 “Standard Test Method for Evaluating Adhesion by Knife” (Chart 5). The modified version of ASTM D6677 was used in areas where destructive testing was not found to be practical. Any blistering that may have been present was rated in accordance with ASTM D714 “Standard Test Method for Evaluating the Degree of Blistering in Paints” (Chart 6), and the paint dry film thickness was measured with a Positector 6000FN3 Type II gage in accordance with the applicable guidelines set forth SSPC PA2. The visual observations and data collected from the tank follow:
Exterior Close-up visual observation of the coating was limited to the first (lowest) shell course, upper shell areas adjacent to the ladder and the roof. The exterior paint is heavily chalked (ASTM D4214, No. 6) and in overall in good condition. The roof was found to have isolated spots with dark corrosion (CSI Corrosion Grade No. 2) notable on weld seams and on the various tank appurtenances. The paint on the roof was found to have organic growth over most of its surface. Areas of peeling paint were also noted on the ladder and rail assemblies and shell. The peeling on the shell appears to be a result of some chemicals running down the tank wall form above. Some minor rusting is also present on the cathodic protection hand holes. The most notable area with concentrated, dark corrosion was on the throat flange of the center roof vent and the exterior leading edge of the floor plates (lower chine area). The center vent has exfoliation corrosion (CSI Corrosion Grade 4), while the lower chime only has dark rust.
All other paint defects appear to be related to mechanical damage such as light scrapes. The total amount of corrosion on the tank was rated to be less than 0.03 percent of the total surface area (ASTM D610, 9). The paint dry film thickness was measured to be 10 to 11 mils on the roof and 7 to 8 on the shell. Paint adhesion was estimated to be satisfactory (ASTM D3359, 4). The data collected from the exterior follows:
Interior Close-up visual observations were made to all areas below the waterline and all other areas were assessed from the water level. The coating on the underside of the roof plates is in fair condition with areas of spot corrosion and peeled coating. The corrosion that is present is primarily on the edges of the support beam flanges and roof plates.
Each of these areas has dark rust (CSI Corrosion Grade 2)m and the spot rust has undercutting. The total amount of corrosion on the roof was rated to be approximately less than 0.1 percent of the total surface (ASTM D610, 6), and there was a relatively large amount of rust staining present. It was also noted that a few of the roof rafters may have shifted or slightly warped
The lining on the shell and floor was found to be in fair condition with a few isolated areas with dark rust (CSI Corrosion Grade 2). However, the lining below the overflow was found to have widespread blisters, and many of these blisters have cracked caps.
Blisters were rated as 4 medium (ASTM D714). There were also some localized areas where the lining has topcoat peeling, notably along a few weld seams. There are also some areas that appeared to have involved underwater patching with white epoxy, and these areas appear to be performing properly. The total amount of corrosion on the shell and floor was rated to be less than approximately 0.03 percent of the total surface (ASTM D610, >9). The data collected from the interior follows:
Discussion
The exterior paint system is heavily chalked, relatively thick, but in overall good condition. The exterior paint mostly has only negligible rust spots in isolated areas. The exterior paint system should continue to provide satisfactory corrosion protection for many years to come, and the only need for wholesale, widespread paint work at this time would be based on aesthetics. Although there are no widespread paint defects, it would be prudent to make some isolated spot repairs as soon as possible to the most heavily corroded areas on the center vent. It was also noted that the roof of the tank is mostly covered with an organic growth that does not appear to be affecting the performance of the paint.
Overall, the interior lining system above the highest water level (HWL) is in fair condition with scattered, isolated areas of corrosion primarily on the edges of both the roof support structure and the roof plates. Peeling lining was also present in many isolated areas. These areas with peeling lining appeared to extend from an intact undercoat and no significant corrosion was associated with this condition. It was also noted that a few beams appeared to have shifted a few inches, but this possible beam movement appears to be an old condition and not the result of recent forces. From a corrosion perspective, the amount of rust below the HWL is relatively minor, but most areas of the lining have blistered. The caps of many of these blisters have cracked. Although many of the caps to the blisters have cracked, no widespread significant corrosion was found to be present - likely the result of the operation of the CP system.
Generally speaking, there are four possible approaches to maintenance painting. The coatings can be either completely removed and replaced (repainted), spot repaired, spot repaired and overcoated, or simply overcoated. In evaluating the condition of a coating to determine the best painting approach there are a number of different factors to consider. The first set of factors includes the determination of the coating's ability to withstand the added stress of an additional coat(s). Attributes impacting this decision include film thickness and adhesion. If the paint film is too thick or has poor adhesion, the tension from the curing stresses and/or weight of the additional paint can cause the existing system to disbond. The second set of factors to consider when determining what painting approach to take is the amount of surface area requiring repair, the overall difficulty in providing access to the structure, and whether the coating system contains heavy metals (i.e. lead, cadmium, and chromium). The final factor is the condition of the substrate.
When considering whether a spot repair approach is a viable option, a good rule of thumb is that spot repair, with or without overcoat, makes sense with up to 10 percent of the surface area requiring repairs. With more than 10% in disrepair, making spot repairs and overcoating becomes a diminishing return. With 10 percent rusting, overcoating may be an option if the adhesion is better than fair. If there is more than 10 percent rusting and the substrate is free of mill scale, overcoating may be considered an option if the adhesion is excellent. Once the amount of surface area in need of repair exceeds this range, the cost of cleaning and coating the individual rust spots approaches (or exceeds) the total cost of removal and replacement.
The interior lining is believed to be approximately 25 years old, but its condition is what would more commonly seen in a system that is 35 years old. It is suspected that the peeling lining and blistering defects developed a few years after the lining system's installation. With respect to corrosion, the area above the HWL is in much worse condition that the lower area due to the operation of the CP system. It is projected the tank will not see the development of advanced corrosion for at least 5 more years.
Although it is not corroding, the lining below the HWL is also nearing the end of its service life and should be included in any future relining work to better amortize the cost of a contractor working in the tank. Simply put, the CP system will soon not be able to adequately protect the steel as the extent of the cracked blisters continues to grow. On this basis, it is recommended that the tank be placed back on a normal 3 to 5 years maintenance inspection cycle as recommended by AWWA with an eye on relining the tank soon after.
It was also noted that piping enters the tank through the floor and this can be problematic during a seismic event. The relocation of these connections to the shell should be considered as part of any future large-scale maintenance work on the tank.
Recommendations
1) As soon as possible, spot repair the corroding areas of the exterior center roof vent. Otherwise, no work is recommended on the exterior paint system.
2) It is recommended that the tank interior be reinspected in 3 to 5 years as part of its normal maintenance inspection cycle with an eye on relining the entire tank soon after.
3) Consider relocating the interior tank bottom piping to the shell.
NOTICE: This report represents the opinion of CSI Services, Inc. This report is issued in conformance with generally acceptable industry practices. While customary precautions were taken ensure that the information gathered and presented is accurate, complete and technically correct, it is based on the information, data, time, and materials obtained and does not guarantee a leak proof tank.
© Copyright CSI Services 2014
Floor
Caulking No ColumnsRoof two shell manways
Bolt circle with hinge round hinge
Near edge
No. & Type Roof Access
Yes no
Tank Foundation noneone
Tank Piping
Ext Ladder Fall Prevent
Ext Ladder Satisfactory
Anti-climb
Yes one
Hatch Design
No. Roof Vents/Location
Floor inlet and outlet
1231 in
Yes
Overflow Exterior Design
Drain Location
Water Level Indicator
The information reported was obtained using visual observations and testing believed to be accurate. The information reported represents the data obtained from the specific representative areas inspected, tested, and/or verified. This document shall only be produced in its entirety.
24 in
Tank Type
Contract No.
Erection Year
Roof Design
Height of Each Course
No. Roof Hatches/Location
Size of Roof Hatch three
Center
Scope
Yes
Number of Courses
Site Information
Diameter (feet) Yes
Client Contact:
Tank Owner/Client:
Tank Name:
City of Watsonville
Airport Tank
Beau Kayser
Dive Supervisor:
Justin Sweeney
Anthony Braschler capped stub
Yes
Yes
Yes
NotesItem
Date of Last Inspection
Ladder
24 in
Impressed Current
No
Steve Metcalf
Ladder
Dive Tender
Dive Leader:
1 of
Steve MetcalfCompleted By
CSI Job No.
Page
219031 WednesdayMarch 27, 2019
P.O. Box 801357, Santa Clarita, CA 91380
Water Agitator
Yes
DatePhone: 877.274.2422 (toll free)
Fax: 661.755.7628 www.CSIServices.biz
Field Water Tank Dive Inspection Report
Description
Interior Structural Characteristics
Roof Accessible
Overhead Power Lines
Water Depth
No
Tank Geometry
Pitched roof with knuckle
No. of Columns none
24 ft
Item
GPS Coordinates
Cross Street
Tank Location
Surrounding Site Asphalt
Nearest Structures
Emme Ln
29 Emme Ln, Freedom Ca
36.9377 -121.7813
Roof Structure rafters, girder and eight total columns
Pipe
Item
Column Design
No
Yes
Pump house
No. Interior Ladder
Outlet Design
Perimeter Fencing
Site secured on arrival
Data
Antenna on Tank
Item Data
No floor stub
Connections
Column Base Design
Bolted
Free plate with stabilizing clips
CP System/TypeUpper Center Column Dollar plate
Inlet Interior Design
Overflow Design Funnel and pipe, floor exit Barrier Walls
Capacity (gallons)
Exterior Structural Characteristics
3,000,000
Lining Type/Original
Item
Epoxy
DataItem Data on grade
Overflow Pipe Diameter
Flexible Pipe Coupling
Outlet Diameter
Inlet Diameter
8 ft
Roof Rail Satisfactory
Roof Rail SystemHeight (feet)
Center Roof Vent Size
Tank Profile
Roof Vent Sealed
Rail Location Top of ladder
Type of Manways
No. Shell Manways
Diameter of Manways
Manway Cover Design oneWelded Steel
Round
Cylinder
Cage
Yes one
Roof Tie-Off Present
Alkyd
Tank Type Potable
Yes
Concrete ringwall
Exterior Vandal Deterrent
Miscellaneous Notes
Round Hood
Construction Co. San Louis Tank Yes
Maintenance Inspection
7 + 1
Roof Vent Design
Lining Type/Original
Airport Exterior Photo (1) Airport Exterior Photo (2)
Airport Exterior Photo (3) Airport Exterior Photo (4)
Airport Exterior Photo (5) Airport Exterior Photo (6)
Airport Exterior Photo (7) Airport Exterior Photo (8)
Airport Exterior Photo (9) Airport Exterior Photo (10)
Airport Exterior Photo (11) Airport Exterior Photo (12)
Airport Exterior Photo (13) Airport Exterior Photo (14)
Airport Exterior Photo (15) Airport Exterior Photo (16)
Airport Exterior Photo (17) Airport Exterior Photo (18)
Airport Exterior Photo (19) Airport Exterior Photo (20)
Airport Exterior Photo (21) Airport Exterior Photo (22)
Airport Exterior Photo (23) Airport Exterior Photo (24)
Airport Exterior Photo (25) Airport Exterior Photo (26)
Airport Exterior Photo (27) Airport Exterior Photo (28)
Airport Exterior Photo (29) Airport Exterior Photo (30)
Airport Exterior Photo (31) Airport Exterior Photo (32)
Airport Exterior Photo (33) Airport Exterior Photo (34)
Airport Exterior Photo (35) Airport Exterior Photo (36)
Airport Exterior Photo (37) Airport Exterior Photo (38)
Airport Exterior Photo (39) Airport Exterior Photo (40)
Airport Exterior Photo (41) Airport Exterior Photo (42)
Airport Exterior Photo (43) Airport Exterior Photo (44)
Airport Interior Photo (1) Airport Interior Photo (2)
Airport Interior Photo (3) Airport Interior Photo (4)
Airport Interior Photo (5) Airport Interior Photo (6)
Airport Interior Photo (7) Airport Interior Photo (8)
Airport Interior Photo (9) Airport Interior Photo (10)
Airport Interior Photo (11) Airport Interior Photo (12)
Airport Interior Photo (13) Airport Interior Photo (14)
Airport Interior Photo (15) Airport Interior Photo (16)
Airport Interior Photo (17) Airport Interior Photo (18)
Airport Interior Photo (19) Airport Interior Photo (20)
Airport Interior Photo (21) Airport Interior Photo (22)
Airport Interior Photo (23) Airport Interior Photo (24)
Airport Interior Photo (25) Airport Interior Photo (26)
Airport Interior Photo (27) Airport Interior Photo (28)
Airport Interior Photo (29) Airport Interior Photo (30)
Airport Interior Photo (31) Airport Interior Photo (32)
Airport Interior Photo (33) Airport Interior Photo (34)
Airport Interior Photo (35) Airport Interior Photo (36)
Airport Interior Photo (37) Airport Interior Photo (38)
Airport Interior Photo (39) Airport Interior Photo (40)
Airport Interior Photo (41) Airport Interior Photo (42)
Airport Interior Photo (43) Airport Interior Photo (44)
Airport Interior Photo (45) Airport Interior Photo (46)
Airport Interior Photo (47) Airport Interior Photo (48)
Airport Interior Photo (49) Airport Interior Photo (50)
Airport Interior Photo (51) Airport Interior Photo (52)
Airport Interior Photo (53) Airport Interior Photo (54)
Airport Interior Photo (55) Airport Interior Photo (56)
Airport Interior Photo (57) Airport Interior Photo (58)
Airport Interior Photo (59) Airport Interior Photo (60)
Airport Interior Photo (61) Airport Interior Photo (62)
Airport Interior Photo (63) Airport Interior Photo (64)
Airport Interior Photo (65) Airport Interior Photo (66)
Airport Interior Photo (67) Airport Interior Photo (68)
© Copyright CSI Services, Inc. 2004
Chart 1 - Condition Rating The table below gives a basic description of the four different categories that CSI Services, Inc. uses to provide a general depiction of the condition of each defined area of a structure. The categories are Poor, Fair, Good, or Excellent. The development of these categories is based on historical knowledge and experience of various paint and lining systems over given periods of time in certain service environments. Basically, the rating is determined based on what should be expected of the paint or lining system at that point in its life cycle. As a result, different determinations are made for maintenance inspection versus warranty inspections. A detailed description of each rating with relative consideration addressed follows:
General Description of Conditions Rating
Maintenance Inspection Warranty Inspection
Poor
This condition is usually prioritized for rework in the short-term. Typically, these surfaces have considerably more coating defects and/or corrosion than what is expected for the age of the system.
This condition identifies an area with wholesale coating defects or corrosion concerns that will typically require significant removal and replacement of the coatings in the area.
Fair
Typically, these surfaces have a level of coating defects and/or corrosion that is slightly worse than what should be expected for the age of the system. This condition is placed on a short-term monitoring schedule.
This condition identifies an area with partial coating defects or corrosion concerns that will require significant rework.
Good
This condition is rated for areas without any considerable coating defects or corrosion. These surfaces are in a condition that is typical for the age of the coating system.
This condition identifies areas with coating defects or corrosion that is typically seen in one-year warranty inspections. Typically, only minor spot repairs are required.
Excellent
This condition is for areas without any considerable coating defects or corrosion.
Typically, these surfaces are in a condition that is better than expected for the age of the system.
This condition identified areas that typically are in perfect condition and require no repair work.
Copyright CSI Services, Inc. 2004
Chart 2 -Rust Grade The black and white figures below depict the standards referenced in ASTM D610 “Standard Test Method for Evaluating Degree of Rusting on Painted Surfaces.” Below each standard is a photographic depiction of each level of corrosion, as used by CSI Services, Inc. The standards depict the percentage of rust on a scale from 0 to 10, with 10 having no rust and 0 having complete rust.
Rust Grade 10 Rust Grade 9 Rust Grade 8 Rust Grade 7 Rust Grade 6
Rust Grade 5 Rust Grade 4 Rust Grade 3 Rust Grade 2 Rust Grade 1
Rust Grade 0
Rust Grade Description 10 No rusting or less than 0.01% of surface rusted
9 Minute rusting, less than 0.03% of surface rusted
8 Few isolated rust spots, less than 0.1% of surface rusted
7 Less than 0.3% of surface rusted
6 Excessive rust spots, but less than1% of surface rusted
5 Rusting to the extent of 3% of surface rusted
4 Rusting to the extent of 10% of surface rusted
3 Approximately one-sixth of the surface rusted
2 Approximately one-third of the surface rusted
1 Approximately one-half of the surface rusted
0 Approximately 100% of the surface rusted
Chart 3 - Corrosion Grade The figure below depicts the photographic standards referenced by CSI Services, Inc. in the determination of the characteristics and stages of corrosion progression. This standard is used to better quantify the level of corrosion once it has progressed to Rust Grades 3, 2, 1, or 0 (see Chart 2). When applicable, CSI classifies an area as one or more of the five different Corrosion Grades. Corrosion Grades 1 through 5 are described below:
Grade Description Photo Examples
Light Rust - This condition involves relatively light colored rust that does not have any significant metal loss.
Dark Rust -This relatively dark colored, thicker rust that is progressing towards the next phase, significant metal loss.
Pitting - This isolated or widespread deep spot corrosion (pitting).
Scale - Also known as lamellar or exfoliation corrosion.
The edges of the affected area are leaf like and resemble the separated pages of a wetted book.
Structural Loss - This metal loss or failure where components will require structural consideration
The photos depicted are examples and were not taken on this project.
Chart 4 - Chalking The figure below depicts the photographic standards referenced in ASTM D4214 “Standard Test Method for Evaluating the Degree of Chalking of Exterior Paint Films,” Method D659, Method C. Generally speaking, chalking is the degradation of a paint’s binder leaving behind loose pigments as the binder reacts with the environment, primarily ultraviolet light and oxygen. Evaluating chalking is a means to measure the performance of a coating system and its life cycle projection. It is also important to quantify for consideration of future overcoating options. This test uses these pictorial standards to quantify the amount of chalking present on paint films. The depictions below represent the mount of colored chalk removed onto a cloth during the test. The scale ranges from 2 to 8 with the rating 2 having the most chalk.
Light Colored Paints
No .8 No. 6 No .4 No. 2
Dark Colored Paints
No .8 No. 6 No .4 No. 2
© Copyright CSI Services 2004
Chart 5 - Adhesion Rating The figures below depict the photographic standards and criteria referenced in ASTM D3359 “Standard Test Method for Evaluating Adhesion by Tape Test” and ASTM D6677 “Standard Test Method for Evaluating Adhesion by Knife.” Both Standards are used to assess the condition of a paint system for life-cycle projections. It is also used to evaluate an existing paint system’s ability to withstand the added stress that any overcoating strategies can create. Depending upon the thickness of the paint system, ASTM D3359 has two different test methods. The rating criteria for both standards follow:
ASTM D3359
Method A Method B
Rating Observation Surface of X-cut from which flaking/peeling has occurred
Rating Percent Area
Removed
Surface of cross-cut area from which flaking has occurred for six parallel cuts and adhesion range by percent
5A No peeling or removal
None
5B 0% none
4A Trace peeling or removal along incisions or their intersection
4B Less than 5%
3A Jagged Removal along incisions up to 1/16” on either side
3B 5 – 15%
2A Jagged removal along most of incisions up to 1/8” on either side
2B 15 – 35%
1A Removal from most of the area of the X under the tape
1B 35-65%
0A Removal beyond the area of the X
0B Greater than
65%
ASTM D6677
Rating Description 10 Fragments no larger than ” x ” can be removed with difficulty 8 Chips up to ” x ” can be removed with difficulty 6 Chips up to ” x ” can be removed with slight difficulty 4 Chips larger than ” x ” can be removed with slight pressure 2 Once coating removal is initiated by knife, it can be peeled at least ” 0 Coating can be peeled easily to length greater than ”
Chart 6 – Blistering Rating The figure below depicts the photographic standards referenced in ASTM D714 “Standard Test Method for Evaluating Degree of Blistering of Paints”. This test uses these pictorial standards to quantify both the size and density of blisters that may develop in linings. Although the standard uses a blister size scale of 0 to 10 this chart uses the most common sizes of blisters found in the field. The standard does not use a reference for the size of each of the blisters depicted. CSI used this scale as a means for further quantification by qualifying the largest blister depicted as being 1 inch in width (Blister Size No. 2) and the smallest blister being 1/32 of an inch in width (Blister Size No. 8).
Few Medium Medium Dense Dense
Blister Size No. 2
Size No. 4
Size No. 6
Size No. 8
| Copy of 219031 Watsonville Airport 032719.pdf |
| Airport Exterior.pdf |
| Airport Interior.pdf |
| Charts 1 to 6 Steel Tank R1.pdf |
| Chart 1 P F G E R1.pdf |
| Chart 2 ASTM D610 Rust R1.pdf |
| Chart 3 Corrosion R1.pdf |
| Chart 4 ASTM D4214 Chalking R1.pdf |
| Chart 5 ASTM D3359 D6677 Adhesion R1.pdf |
| Chart 6 ASTM D714 Blistering R1.pdf |
File details come from the government source that posted it. Updated .