Chapter Quesrions #2 Flashcards
High humidity during coating application:
Slows the evaporation of the solvent
Can leave moisture on the surface of the coating
May cause amine blush (must be removed prior to top coating)
May effect the gloss or color
Coatings may be applied by the following methods:
Roller
Brush
Airless spray (including plural component) Brush
Conventional spray
Airless spray (including Air Assisted Airless)
High Volume Low Pressure (HVLP)
High Conventional spray
High temperatures concerns during coatings application include:
Can cause the solvent to evaporate too fast
Will reduce the pot life
Decrease the viscosity of many two-component materials
Low temperature concerns during coatings application include:
Slow the curing of chemically curing coatings
Will increase the viscosity of material
Some coatings may use special cure
One guide for enclosures for coatings projects is:
SSPC Technology Guide No. 12
SSPC Technology Update No. 6 Guide for Containing surface
Preparation Debris Generated During paint removal operations
Documentation may include:
Detailed written daily report Inspection logs Routine reports Reports for weekly progress Daily entries in a project log book A daily inspection report using standardized forms Monthly or quarterly reports
Inspection records show:
Pretreatment Details Environmental conditions Cleaning details Materials Details Coating applications Details Materials Details Results of work and all test
Good records allow management to:
Evaluate coating performanc
Detect and tag design defects for future work
Determine annual cost data on each coating system
Develop ongoing maintenance program
Project inspection documentation provides:
Inspection (QC) records
Verification of work performed by the contractor
Management information
Details of non-conforming work
Goals of a Pre Job Conference include:
Discuss health, safety and environment (HES) Requirements f a Pre Job
Address/ clarify emergency procedures
Review and discuss scope of work (SOW)
Review logistical support
Discuss line communications between parties
Review known critical hazards
Establish list of critical point of contacts (POCS)
Discuss and clarify inspector (s) responsibilities and authority
Clarify the chain of command (Reporting system)
Discuss and clarify inspector (s) responsibilities and authority
Discuss and clarify areas of concern in the project specification
(Omissions, clarifications, testing)
Agree on critical hold points for inspections
Conflict resolution between the inspector and applicator
Change orders
People may be required to attend a pre-job conference include:
Owner
Owners contract manager
Engineer
Operations personal
Specifier
Specifying engineer
Purchasing agents
Coatings Inspector (s)
Coatings applicator (Supervision personnel)
Project safety personnel
Coating manufacturer (preferably tech, service rep)Before the start of the Pre Job Conference the inspector should obtain a copy of, read, and understand the:
Specification
Any standard / procedure referenced in the project specifications
Manufacturer’s product data sheets
Safety requirements of the MSDS
When using Replica tape common errors include:
Variation in point-to-point profile over the surface being tested
The presence of particles of dirt on either the replica tape or gauge
Gauge Accuracy
The rubbing or burnishing technique
List the Standards for using the Replica tape:
ASTM D 4417 Method C
NACE SP 0287-2002
The two types of replica tape are commonly used:
Coarse—for 20 to 64 µm (0.8- to 2.5-mils)
X-Coarse—for 38 to 115 µm (1.5- to 4.5-mils)
The ISO Comparator grades may be recorded:
Finer-than-Fine Grade Fine Grade Medium Grade Coarse Grade Coarser-than-Coarse Grade
Depth of surface profile can be evaluated by several methods:
ISO Comparator
Replica tape
Digital Profile Gaug
Test for soluble salts include:
Bresle Patch
Sleeve Test
Soluble Salt Meters
Conductivity Meters
If inspection is to be effective with regards to soluble salts, the specification should very clearly state:
Limits to be accepted Specific salts to be limited Test method to be used Frequency of testing Locations in which tests should be administered
Types of Soluble Salt Contamination include:
Chlorides
Sulfates
Nitrates
Coatings Product Data Sheets (Paint Specs) provide users with the following:
Surface preparation Storage Mixing and thinning Application procedure DFT requirements
MSDS contains the following:
Provides workers and emergency personnel with critical information
on composition, handling or working with the substance
Includes information such as melting point, boiling point, flash point,
toxicity, health effects, first aid, reactivity, storage, disposal,
protective equipment, and spill handling procedures.
Provides information regarding the safety issues associated with any
hazardous (or potentially hazardous) material.
Provides instructions for the correct action to take in the event of a
spill, explosion, fire or hazardous exposure.
During surface preparation, surface cleanliness should be inspected (as a minimum) the following three (3) times:
Before any surface preparation activities
After surface preparation, before coating begins
Between each application of coating in a multi-coat system
Factors during surface preparation that may effect service life include:
Residues of oil, grease, and soil
Residues of (non-visible) chemical salts
Rust on the surface
Loose or broken mill scale
Rust scale
Anchor pattern
Defects mechanical cleaning equipment
Surface condensation
Old coatings that have poor adhesion/too deteriorated for recoating
Existing coatings that may be incompatible
Common design defects include:
Hard-to-reach or inaccessible areas
Rivets, bolts, or other connectors
Welds
Gaps (particularly skip welds or surfaces close together)
Overlapping surfaces (e.g., roof plates in water tanks)
Angle iron badly oriented or in complex arrangements
Threaded areas
Dissimilar metals
Sharp edges, particularly on corners or rough cut plate
Construction aids
Common fabrication defects include:
Weld Spatter
Skip Welds
Rough Welds
Sharp Corners & Edges
Four (4) Typical SSPC SP1 pre-cleaning methods include:
Solvent wipe with cloth or rag Immersion of the substrate in solvent Solvent spray Vapor degreasing Steam cleaning Emulsion cleaning Chemical paint stripping Use of alkaline cleaners
One Standard for use with Power Tool Cleaning is:
ISO St2
ISO St3
SSPC SP-3
SSPC SP-11
Four (4) Examples of tools used for Power Tool Cleaning are:
Rotary Wire Brushes Impact tools Needle Scaler Rotary Scalers Piston Scalers Grinders and sanders Disc Sanders
Abrasive Blasting methods include:
Centrifugal blasting Sand-injected water blast Slurry blast Wet abrasive blast Dry Grit Blast Cleaning (Air Blasting)
Visual Standards for abrasive blasting include:
SSPC-Vis 1
ISO 8501-1
SSPC SP 10/NACE 2
SSPC SP 5/NACE 1
SSPC SP 6/NACE 3
limits staining to 5% per each unit area
limits staining to 0% per each unit area
limits staining to 33% per each unit area
The two (2) types of abrasive blasting nozzles include:
Straight
Venturi
Failure of coatings to cure may be caused by:
Not adding curing agent, wrong curing agent or incorrect amount of it
Problem with material from the manufacturer
Environmental issues (too cold, hot, or humid)
Wrong or contaminated thinner (Solvent)
Some of the problems that can be caused by amine blush are:
Surface tackiness or greasiness Incomplete curing Poor adhesion Coating discoloration Poor gloss retention
Runs, Sags, and wrinkles may be caused by:
Applying the coating too thick Too much or the wrong thinner used Surface too hot to apply the coating Application of coating at the end of its pot life Wrong thixotrope used in manufacturing
Chalking
is a powdery, friable layer on the surface of a coating that is most
common with epoxy coatings.
Cratering may be caused by:
Air trapped in the coating and forming a bubble which then bursts
Air trapped in the coating during mixing if the proper procedures are not followed
Vacules or voids are typically caused by:
Running the mixer too fast
Pinholes are:
Very small holes in a coating typically caused by air or solvent trapped in porous film and
escaping.
A common cause of blistering is:
Surface Contamination under the applied coating
Cracking of a coating is noted:
When the crack extends to the substrate
Fine cracks in the surface of a coating that don’t extend through to the substrate
Checking
Adhesion failures may be caused by:
Contamination on the surface Wrong surface preparation specified Failure to inspect surface preparation Insufficient surface profile Exceeding the topcoat window Application of incompatible coatings Applying the coat to a glossy surface
General types of holiday detectors include:
Low-voltage DC - under 20 mils
High-voltage DC - over 20 mils
High-voltage AC - do not use ground wire (use a 110v or 220v power supply) emits a spark
Nace SP0188 low and high voltage direct current
Use 100 volts per mil
Low-voltage (wet-sponge) holiday detectors are powered by batteries
- with output voltages ranging from 5 to 120 V DC
- use tap water used for 20 mils or less
- may be used on concrete
Describe Low-voltage (wet-sponge) holiday detectors:
Ground cable is attached directly to substrate
Sponge saturated with a solution of tap water/wetting agent
Maximum rate of 30 cm/s (1 linear ft/s) double stroke
Used on coatings up to 500 µm (20 mils)
May be used on concrete.
High Voltage DC Holiday detector types include:
DC – Pulsed
DC – Constant Current
The type of High Voltage Holiday detector used for concrete is a:
High Voltage DC Constant Current
What is a Standard?
An established norm or requirement that is written by industry professionals
A formal document that establishes uniform engineering or technical criteria, methods, processes and practices
What percentage of NACE Standards relate to coatings:
50%
Alligatoring
When hard coat is applied over a soft extensible coat
Or applied to thickly and exposed to sunlight
Failure on weds and edges problems
Edges
Coating tends to pull away from the sharp edges
Edges should be rounded to at least 2mm radius
Welds
Spatter should be removed
Heat can harden steel
Holiday detection inspection consideration
Work environment Type of substrate Specification requirements Type of coating and thickness Standard to be followed
Confined space types
Class A - immediate danger to life and health
Class B - no immediate danger to life and health
Class C - potential hazard not required to modify work or surrounding
Class D - documented low hazard
