FROSIO Certification Course (필기 시험 정리 요약본)

FROSIO Certification Course (필기 시험 정리 요약본)

 

 

 

FROSIO 시험을 치른 지 어느새 10년이 넘었고 5년에 한번씩 갱신을 하니 2번이나 하게 되었습니다. FROSIO 갱신비가 수수료 포함 20만원 정도 합니다. NACE는 카드 결재가 되는 것으로 하는데 FROSIO는 현금으로 해당 은행에 입금을 해야 하는 불편함이 있습니다. 현금으로만 받는 것을 보니 뭔가 구리기도 하고…

 

FROSIO 마크도 왼쪽에서 오른쪽으로 새롭게 변경되었더군요

 

 

아무튼 몇 개월 전에 FROISO 갱신 기간이 초과된 것을 알았습니다. 그래서 갱신 작업을 하다 보니 기타 서류 양식도 많이 바뀌었더군요. CV도 update 하려고 하니 내가 어떤 프로젝트 했는지 기억도 잘 안 나고 또 생각보다 시간이 많이 걸리고 귀찮기도 했습니다. 그러다가 이전에 정리하고 중간에 후배들에게 주려고 필기 시험 정리 요약본을 만든 게 생각이 나서 혹시 필요한 사람이 있으면 도움을 주고자 블로그에 올립니다.

 

아래 내용 참고 하시길 바랍니다.

 

Abrasive

In general – two main groups of abrasives

Metallic abrasives

1.     Chilled iron grit

2.     High-carbon cast steel grit and shot

3.     Low-cast steel shot

4.     Cut steel wire

 

Mineral (or non-metallic) abrasives

Natural mineral abrasives

1.     Garnet

2.     Olivine

3.     Staurolite

Slags

1.     Copper refinery slag

2.     Nickel refinery slag

3.     Coal furnace slag

4.     Iron furnace slag

5.     Fused aluminium oxide

 

Shape of abrasives (Three main shapes of abrasives)

l   Grit (angular)

l   Shot (round)

l   Wire cut (cylindrical)

 

Checking the abrasive for water-soluble contaminants (ISO 11127-6)

1.     According to ISO 11127-6

2.     Mix 100g of abrasive with 100ml water

3.     Shake for 5minutes and let stand for 1 hour

4.     Conductivity measurement of many non-metallic abrasives maximum 25ms/m or 250㎲/㎝

 

Corrosion

Corrosion: deterioration or breakdown of materials (metals) due to a reaction with the environment

Rust is a product due to corrosion of steel

 

Corrosion environment: gas, salt, ph, humidity, sulphur, oxygen

 

What is need for corrosion to occur?

1.     Oxygen

2.     Electrolyte (water/humidity)

3.     Material - Potential difference with metal

 

Anode: metal surface where corrosion take place

Cathode: metal surface on which reduction take place.

Electrolyte: electrically conductive liquid such as sea water.

Reference electrode: an electrode that maintains a constant reference potential. No electric current passes through this electrode

 

Ignoble and noble metallic

l   Ignoble metal have a high tendency to give off electron

l   Noble metal have a low tendency to give off electron

 

Cathodic protection (3가지, 그림으로 설명 가능해야 됩니다)

Method of reducing the rate of corrosion by makes it cathodic.

 

 

1.     Paint (silicate, ZN)

2.     Sacrificial anode system

3.     ICCP

l   Use of impressed current anodes? Platinum, platinised titanium, graphite, magnetite.

 

l   Cathodic disbonding? Using impressed current systems creates large amounts of hydrogen gas. This will promote adhesion failure of the coating. The phenomenon is called cathodic disbonding.

 

l   What is the purpose of the additional use of sacrificial anodes in the stern of the vessel? Bronze propeller

 

Kind of corrosion – Corrosion 문제는 기출문제를 많이 풀어봐야 됩니다.

 

Galvanic corrosion (bimetal corrosion)

l   Electric contact between dissimilar of metal in an electrolyte

l   Potential difference, area/size of the cathode are the anode

 

ex) What happens if steel and zinc are in electrical contact in seawater?

l   Zinc will corrosion because zinc is more ignoble and protects steel.

 

What happens if steel and copper are in electrical contact in seawater?

l   Steel will corrosion because steel is more ignoble and protects copper.

 

Galvanic corrosion can be reduced by:

1.      Insulation: Non-metallic washers, gaskets, barrier coatings

2.      Avoid combinations of metals far apart in the galvanic series

3.      Design

 

# Galvanic series?

The ranking of metal and other conductive material increasing or decreasing tendency to corrode

 

Crevice corrosion (deposit corrosion)

l   Localized attack within crevice, shielded area

l   Oxygen content within the crevice

l   Dangerous to passive metal

l   Small volume of stagnant solution

 

Erosion corrosion (turbulence corrosion)

Roughened surface due to, e.g. mechanical wear or too high velocity of liquids inside pipes

 

Stress cracking corrosion (SCC)
on metal with internal stress which are exposed to a corrosive environment

Especially sensitive metal: stainless steel in chloride environment

l   Stainless steel ~ in seawater

l   Copper alloy ~ in ammonia

l   Carbon steel ~ nitrate solution

 

Pitting corrosion

l   More or less evenly as small holes in the metal.

l   Specially sensitive metal: steel, stainless steel, copper, aluminium.

 

Selective corrosion (Dealloying corrosion)

The most active element is removed from solid a some alloy in corrosive environment

 

l   De-zincficaton of brass (yellow -> red)

l   Graphitization of cast iron (grey -> black)

 

 

Microbiologically induced corrosion (bacteria corrosion)

Deterioration of a metal by corrosion processes which occur as a result of a living organisms.

 

General corrosion

l   Even regular loss of metal from the corroding surface.

l   Occurs on all metals

Cavitation corrosion

• This type of corrosion starts due to the creation of steam bubble that collaps(explode) onto the surface. This tears away the metal.

Paint and paint systems

 

Paint 5가지 구성요소

Binder

l   Give the durability, adhesion

l   Provide flexibility, cohesion

l   Non-volatile paint

l   ex) epoxy, alkyd, acryl

 

Pigment

l      Provide the color and opacity

l      Non-volatile paint

l      Contribute to the hardness and abrasion resistance

l      ex) decorative - iron oxide(yellow/red), TiO2(white),organic pigments(bright blue, red, yellow)

l      ex) anti corrosion - iron oxide(yellow/red), zinc dust, aluminium flakes, red lead

 

Opacity 제공하는 pigment (color를 주는 Pigment 라고도 나옴)

TIO2 (white), compound of iron, calcium (read, yellow)

 

 

Anti corrosive pigments

1.     Micaceous iron oxide (MIO): increased durability to the paint, reduced permeability, increased tensile strength. (그림으로 설명 하면 좋습니다.)

2.     Aluminium flakes: Leafing pigments flow to the surface, non-leafing pigments are evenly distributed in the film.

3.     Zinc dust (spherical pigments): binder may be epoxy (particle to particle contact is needed), binder may be ethyl silicate (conductive)

4.     Zinc phosphate: white spherical pigment, increased durability to the paint, provides inhibitive protection

 

 

Extender

l   Provide body to the paint

l   Often add as a form of cheap paint pigment

l   General used to modify the paint properties

l   ex) silicas(SiO2), silicates, carbonates

 

Solvent

l   Volatile part

l   Dissolve the binder

l   Solvent is used to reduce viscosity to level of suitable application

l   ex) alcohols, ketones(MIBK,MEK), xylene, white-spirit

 

Additive

l   Enhancement of desired properties

l   Very small amount

l   ex) anti-skin agents, catalysis, viscosity-modifiers

 

 

The paint films protect in three ways

ü  Barrier effect(방호도료)

1.     Prevent water and oxygen from reaching the surface

2.     (Vinyl, alkyd, chlorinated rubber, epoxy)

3.     (Pigment: MIO, coal tar, aluminium flack)

 

ü  Inhibitive effect (부식억제도료)

1.     Passive the steel surface

2.     (Zinc-phosphate (epoxy), red-lead (alkyd)

 

ü  Cathodic protection (희생도료)

1.     Sacrificial themselves to protect the steel.

2.     (Zinc- ethyl silicate, zinc epoxy)

 

Dry, curing 3type

l   Physical drying: evaporation of the solvent (vinyl, acryl, chlorinated rubber)

l   Oxidative curing: reaction with oxygen and evaporation of the solvent (alkyd, oil)

l   Chemical curing: chemical reaction between abase and curing agent and (evaporation of the solvent) – epoxy, polyurethane, polyester

 

Minimum apply temperature

종류	Physically	Oxidative	Chemical
Solvent born	-10	+10	+5
Water born	+5	+10	+5

 

Identification of existing coating

Solvent test – drops of a strong solvent e.g.MEK

l   The coating dissolves completely – physical drying

l   The coating is affected and lifts – oxidative drying

l   The coating is not affected – chemical curing

 

The duties of paint system (각 coat별 역할 꼭 알아 두기)

• Primer coat: Supply good adhesion to the steel surface
• Intermediate coat: Increase the film thickness and assure good adhesion of the topcoat
• Topcoat: Withstand weather and give the desired color and gloss

Alkyd paints

Advantages	Limitations
Air drying paint Easy to apply 1 pack paint Good surface wetting Fair weather durability	Fair acid resistance Poor alkali resistance Mod. Water resistance Poor solvent resistance Difficult to recoat alkyds with other coatings(lifting)

 

Polyurethane paints

Advantages	Limitations
Chemical curing Good chemical resistance Excellent weather resistance Good solvent resistance Long lasting topcoat	Difficult to recoat Avoid skin contact Contains isocyanate (carcinogenic)

 

Epoxy Tar paints

Advantages	Limitations
Flexible Improved water resistance Better wetting than pure epoxy	Dark colour Temperature dependant (+10℃) Difficult to recoat due to bleeding carcinogenic

 

Epoxy paints (pure)

Advantages	Limitations
Good chemical resistance Good adhesive properties Good water resistance High mechanical strength	Temperature dependent Minimum and maximum recoat intervals Difficult to recoat if interval is exceeded

 

Epoxy mastic paints

Advantages	Limitations
Surface tolerant Good water resistance Good chemical resistance High content of solids Good solvent resistance Winter curing types	Temperature dependant (+10℃) Tendency to chalk Minimum and maximum recoat interval Amine blushing

 

Zinc epoxy paints

Advantages	Limitations
Short drying time Up to 90% pure zinc Excellent adhesion High mechanical strength	Minimum temperature requirement (+10℃) Not resistant to acids or alkalis Must have zinc particle contact

 

Zinc ethyl silicate paints

Advantages	Limitations
Excellent solvent resistance Very good chemical resistance High heat resistance Good mechanical strength Easy application	Requires at high RH to cure Mud cracking can occur (above 100㎛) Requires high surface profile (medium to coarse) Needs tie – or mist coat

*Why Zinc is ethyl silicate required high R/H? The ethyl silicate binder reacts with H2O(R/H) in the air – Hydrolysis   Then form the film with combination of zinc

 

Anti corrosion pigment (MIO, aluminium flakes, zinc dust)

 

MIO (micaceous iron oxide)

1.     Increased durability to the paint

2.     Increased tensile strength

3.     Reduced permeability

 

 

Aluminium flake

1.     Lifting pigment flow to the surface

2.     Non-lifting pigment are evenly distributed in the film

 

Zinc dust

1.     Binder may be epoxy (particle-to-particle contact)

2.     Binder may be ethyl silicate (conductive)

 

Curing agent of epoxies

• Polyamide: traditional epoxy coatings (pure)
• Polyamine and amine adducts: Solvent free coatings, tank coatings, modern coatings (high solid)
• Iso cyanates: low temperature curing coating

 

Curing agent of urethane: isocyanate

 

Important when using epoxy coating

1.     Mix the paint correct

2.     Pot life

3.     Pre-reaction time

4.     Correct surface preparation

5.     Min and max over coating time

6.     Curing time

7.     Workmanship

8.     Correct file thickness

9.     Good ventilation

10.   Curing dependent of temperature

11.   Avoid high relative humidity during curing 

 

 

Pre-fabrication <Shop primer>

1.     Type: iron oxide (red color) :PVB(poly vinyl butyral), epoxy / zinc(grey color): ethylsilicate, epoxy

2.     DFT: iron oxide (15~20) / zinc rich (10-15) and low zinc -> 20microns

3.     Hazard and health

ü  Inorganic zinc primer: zinc fever is caused by inhalation of zinc fume.

4.     High DFT ~ welding and cutting problem

ü  Welding: defect (blow hole, under cutting)

ü  Cutting: reduce cutting speed

5.     How to check DFT

1.    Place polished steel panel on blasted steel plate before applying

2.    Then pass plate through painting line

3.    Measure DFT of sample plate.

 

TYPE	binder	pigment	DFT
iron oxide shop primer	PVB, Epoxy	iron	15-20
zinc rich shop primer	ethy silicate, epoxy	zinc	15-10

 

Anti-fouling paint

Purpose of antifouling paints

• Reduce growth of fouling

ü  Macrofouling – animals and plants

ü  Microfouling – slime

• Depends on global zones
• Better fuel economy

ü  Smoother surface, less friction

• Corrosion protection

 

Main type of antifoulings (AF)

1. Conventional antifouling
2. Long life antifouling
3. Self-polishing antifouling
4. Biocide free(non stick surface) 

Conventional antifouling (soluble matrix)

l   Binder: rosin

l   Biocide: cuprous oxide

l   Lifetime: approx, 12 month

l   Binder dissolve slowly in water and biocide is released.

 

Long life antifouling

l   Binder: chlorinated rubber, vinyl

l   Biocide: cuprous oxide

l   Life time: 16~ 24 month (150)

l   Binder does not dissolve in water, but biocide leaches out. Can give a porous layer after exposure (over time).

 

 

Shelf polishing antifouling

l   Binder: metal acrylates, organosiyl

l   Biocide: cuprous oxides, zinc compounds, copperomadine

l   Life time: up to 60 months

l   Erosion rate: 75~100㎛

l   Releases biocides through hydrolysis and biocide always present at the surface during life span of the antifouling.

 

Biocide free (non stick coating)

l   Binder: Usually silicone or teflon

l   Biocide: none

l   Life time: up to 60 months

l   Coating provides a smooth and low friction surface where fouling will not grow

l   Requires continuous motion, speed greater than 10-20 knots

l   Film thickness 100-200㎛, can be difficult to recoat, more expensive, 3-4 x TBT self polishing

 

AF의 SPC 3type

1.     Hydrating: polishing through erosion, no smooth effect

2.     Hydrolysis: chemical react in seawater, self-smooth effect

3.     Hybrid: combination of hydrating and hydrolysis binder, give limit self, smooth effect

 

Health and safety

Chemical health hazards

The body takes up chemical substances in 3ways:

• By inhalation
• By skin contact
• By swallowing

 The hazards of dust

• Respirable dust: particle size less than 5㎛,- can get into yours lungs
• Dust lung diseases:

ü  Silicosis caused by inhalation of silica from abrasive / silica(quartz) sand

ü  Asbestosis from dust of asbest

ü  Siderosis from iron oxide dust

• Lung cancer

Solvent가 인체에 미치는 영향

l   Acute: dizziness, headache, discomfort, irritation of skin and eyes.insensibility

l   Chronic:

ü  irreversible effect on the nerval system, brain damage

ü  some solvent: Harmful effect on the kidneys, liver and on the blood

ü  some solvents may cause cancer and some have reproductive hazard to men and women.

 

Hazard ranking (Abbreviations)

l   R- substances: harmful to reproductory organs(R1-R2)

l   C- substances: carcinogenic(C1-C3)

l   M-substances: mutagenic(M1-M2)

 

Risk for cancer in point

l   Binder: coal tar(C2), toluene di-isocyanate(C3)

l   Pigment: zinc chromate(C1), lead chromate(C2)

l   Solvent: benzene(C1), di-chloro methane(C3)

 

 

The hazard during abrasive blasting cleaning:

• Dust
• Noise
• Pressure and particle velocities

*Chemical waste: because the used abrasive contains hazard material such as leas, chromium

 

Noise levels:

• Blast cleaning 100-110 decibel (dB)
• Painting: 100 decibel (dB)
• Thermal spraying: 100-110 decibel (dB) 

* Maximum noise level over an 8-hour day 85dB(A)

 

Approved scaffold should have

1. Toe boards to prevent people and objects from falling
2. Guardrails, usually knee high
3. Handrails, minimum 1meter high
4. Secured floors and ends
5. Floors with no gaps preventing falling objects
6. Constructed to withstand the maximum load
7. Ladders that have sufficient strength, in good condition and secured

Flash point

The minimum temperature at which the mixture of air and solvent vapour can be ignited by a spark or a flame.

LEL (lower explosion limit)

Minimum volume % of vapor from a flammable liquid can cause and explosion

 

UEL (upper explosion limit)

Maximum volume % of vapor from a flammable liquid can cause and explosion

 

TLV (threshold limit valve)

Maximum concentration of solvent, cause not harmful effect to person through the working day

 

OEL (occupational exposure limit)

Average concentration nearly all workers may be exposed with out adverse effect.

 

OAR (occupational air requirements)

The amount of ventilation necessary foe keeping the solvent vapor below the DEL

 

R-phrase:  Risk involved using products, what happen? If you get exposed

 

S-phrase:  protect yourself from risk involved, what do you do? If you get exposed, It can be confirmed from labelling of product or SDS(safety data sheet)

*R은 risk, S는 safety를 의미 한다. 이는 제품에 표기되는 안전과 관련된 문구이다.

 

What is related safety in label of paint?

1.    Chemical substance contribute to health hazard, fire risk

2.    R-phrase, S-phrase

3.    Symbol of health hazard, fire risk

4.    Name, address of manufacture

 

Scaffolding work

1.    Non-skid, fixed platform (no gap)

2.    Provide safety route for working

3.    Guard rails, handrails – protect people or object from falling

 

Thermal spraying of zinc and aluminium

Quality inspection

• Inspection of steelwork before blasting
• Inspection and testing of cleanliness from penetrates, oil, grease and soluble salts
• Blast cleaning and inspection for

ü  Surface cleanliness (Sa 2.5-Sa 3 act. ISO 8501)

ü  Profile medium – Coarse act. ISO 8503

• Ambient conditions during blast cleaning and coating
• Coating inspection and testing

Thermal spray checkpoint

Thermal spray 적용 시 check 사항 ü  Voltage ü  Amperage ü  Nozzle system ü  Wire feed rate ü  Spray distance ü  Spray angle ü  Air pressure ü  Spray skill

Thermal spray 적용 후 check 사항 ü  Surface dry condition ü  Repair method ü  Recoating interval ü  Inspection

 

Thermal spraying 그림 (족보에 떠도는 그림 외우지 말고 Standard 책에 나오는 그림 외우세요)

 

Metallic coating 종류

l   Thermal spray

l   Electrodepositing

l   Dipping

 

Hot dip galvanising

Metalizing - HDG (Hot dip galvanizing)

Alkaline degreasing -> water rinse -> acid pickling (16% hydrochloric acid) -> water rinse -> Flux (zinc ammonium, chloride solution) -> drying -> dipping (molten zinc 440~465) ->cooling -> inspection

 

Surface preparation for painting on the HDG

l   Alkaline washing

l   Sweep blasting

l   Etching primer

 

Comparison of HDG steel to painted steel

Advantages	Limitations
Low price Long lifetime Few defects Good overall quality Good cathodic protection Easy to inspect	Stationary zinc baths Greyish colour A max. size of the structure Heat affected Deviation from normal welding procedures

 

Osmosis

 

Osmotic blistering

1.     Adsorption of water molecular in the film

2.     Inclusion of water in the interface between the film and the substrate.

3.     Corrosion of the substrate

4.     Flacking or peeling of the file

 

*Cause

Osmotic is the passage of water through a semi-permeable membrane from a solution of lower concentration to one of greater concentration.

 

Passive fire protection

Why fire protection?

• To save lives and values
• To protect escape routes
• To gain time until collapsing
• To divide areas

How to check PFP DFT?

·         Pin gauge (drill the hole and measure),

·         Ultra sonic gauge,

·         Calculation of paint quantity

·         W.E.T gauge during coating application

Surface preparation: blast-cleaning of the steel to Sa 2.5 both organic coatings and inorganic coatings

 

Passive fire protection coatings

Organic coatings	Inorganic coatings
Epoxy coatings Thickness 6-30mm Swell and create an insulating layer Products: Chartek, pittchar, termolag, firetex	Cement coatings Thickness 20-40mm Liberates water Products: Mandolite, pyrocrete

 

Concrete

1. Checking point on surface concrete before application

Phenolphthalein indicator should be used and phenolphthalein is a chemical which is colorless below pH=9 AND PINK IF HIGHER THAN Ph=9

 

2. Surface preparation of concrete

Abrasive blasting (using silica sand or other abrasives)

 

3. Concrete mechanism

In alkaline solutions (e.g concrete) steel becomes passive and breakdown of the passive film is caused by acidic, neutralization(carbonation) of the alkalinity.

 

4. How to check concrete DFT

Using by cover meter or Proceq profometer

 

5. Concrete  - rebar corrosion

Acidic gases in the air such as carbon dioxide and sulphur dioxide react with the alkaline components in the concrete reducing or neutralizing the alkalinity.

 

PSPC

1. Meaning, purpose of PSPC 3 parties

3 parties means is that ship owner, shipyard and paint manufacture and PSPC inspection agreement is discussed & completed before new building construction.

 

2. List of inspection or PSPC as 6 items (PSPC 검사 항목 6 가지)

ü  Surface preparation (ISO 8501-1)

ü  Profile test (30~75 microns ISO 8503-1/2))

ü  Salt test (ISO 8502-9)

ü  Dust test (ISO 8502-3)

ü  Weather condition

ü  Strip coating

ü  NDFT measurement

1. PSPC purpose

The standard provides technical requirements for protective coatings in dedicated seawater ballast tanks in all types of ships of not less than 500 gross tonnage and double-side skin spaces of bulk carriers of 150 meter in length and upwards.

 

2. What is NCR?

Ship’s owner is requested to correct work regarding outstanding item through Non-conformity report and NCR should be mentioned finding item, action taken and etc.

 

Specification and procedures

Specification: the specification provides a contractual document for all the technical aspects of the operation in order to reduce disputes to a minimum

Procedure: the procedure describes the way the work will be done/carried out

Standard is specification, practice method or item that has been formally adopted.

Purpose: to have common reference, to minimize dispute

 

Application of paint

Advantages / disadvantages of brush application

1. Relatively clean
2. Use in restricted areas
3. Paint can be worked into difficult areas
4. Good on “poorly” prepared surfaces
5. Brushes can be cleaned
6. Time consuming and expensive

 

Advantages / disadvantages of rollers application

1. Good on large flat surfaces
2. 4-5times quicker than the use of brush
3. Not to be used as method for priming
4. Not to be used for strip coating edges, corners

Advantages / disadvantages of air spraying

Advantages	Disadvantages
Faster than roller and brush Uniform thickness Fine finish Used on cars	High loss Overspray / dry spray Rebounce coating corners, hollows etc. Thinning necessary

 

Equipment of measuring viscosity

Flow cup, e.g Ford cup, DIN cup

 

Advantages / disadvantages of airless spraying

Advantages	Disadvantages
High prod. Rates High viscosity paints can be applied Lower loss of paint Skilled operators	Overspray / dry spray Rebounce coating corners, hollows etc. Wornout nozzles

 

주의사항 during airless equipment operation

1.    Do not point the gun towards the body – high pressure

2.    Hose must be reinforced and should be covered by wire braiding

3.    The gun must be earthed – prevent spark

4.    Nozzle or gun cleaning – the pump must stop

5.    The sprayer must be skillful

 

Stripe coat: paint applied only to edges, corner or to welds on steel structures.

 

Touch up: spot area like small damage

 

The pumps pressure ratio - Air piston area: paint piston area

Airless spray 그림 삽입 (Frosio 교육 시 강사가 가르쳐 주는 그림으로 외우세요)

 

Daily logs and reporting

 

Daily log 작성 목적?

In case of premature failure of the coating, inspection record can be viewed, record is provided a history of the work.

 

 

The daily log should contain

• Headlines with information regarding: purchase number, size of the object, procedures, references.
• All information regarding the surface prep. : climatic onfitions, surface prep., cleanliness, roughness, type of abrasive and grainsize, date and time of surface preparation.
• All information regarding the application of paint: type of paint, batch no., color, demands for DFT for each coat, date and time for start/finish for each coat, temp. and RH.
• All information regarding the application of paint: lowest measured value, highest measured balue, mean value, type of DFT gauge.
• Signatures of approval from client or customer, entrepreneur.

Environmental conditions methods of dehumidification

Ventilation rate: number of time per hour for change of the air with fresh air

 

Two methods to lower the RH

Heating	Dehumidify
l   Relative humidity is lower l   Dew point water vapor content in the air is unchanged	l   Water vapor in the air removed l   Relative humidity, dew point is lowered.

 

Ultra high-pressure water jetting (UHP WJ)

• Advantages: environment friendly, good cleaning effect, water consumption, 12-20 l/min and higher, low salts, temperature rise.
• Limitations: poor sight, flash rust, no surface profile, many standards from manufacturers, work taking place with new ISO standard, debris with heavy metals.

Surface preparation

 

What should you do prior to blasting? Prior to blasting 시 해야 할일?

• Grinding of sharp edges (2mm), lamication
• Grinding of welding spatter, undercut, overlap, remove salt, oil and grease.

What is reason to prefer round and square pipe than L or H beam?

• Round and square pipe type is better than L or H shape type
• Painting and surface preparation are better, cleaning and maintenance are better
• Prevent to corrosion

The surface preparation starts with the preparation of the steel

• Rounding of sharp edges (min.2mm)
• Removal of weld spatter
• Grinding of welds and slivers
• Grinding of flamecut edges

Blast cleaning

• AD: High capacities, large area in short time, provide profile + roughened, good adhesion with primer (by high anchor pattern), effective to removal of mill scale and heavy rust, Utilize kinetic energy
• DIS-AD: small area can’t use, dust problem, safety risk

Removal of oil and grease

l   Cleaning with solvents(SSPC SP1)

l   Cleaning with emulgating solvents

l   Cleaning with alkaline detergents

l   Cleaning with steam

 

The pressure during abrasive blasting cleaning depends upon:

1.     Compressor size(m3)

2.     Hose length

3.     Nozzle size

4.     Normal blasting pressure varies from 6-7bar to 10ba

The determine the actual pressure at the nozzle you can use a (needle pressure gauge)

 

Definitions according to ISO 8501-4 based on SSPC-VIS 4/ NACE VIS7

l   LP WC < 34Mpa (5000psi)

l   HP WC < 34-70Mpa (5000-10000psi)

l   HP WJ < 70-200Mpa (10000-30000psi)

l   UHP WJ  >200Mpa (>30000psi)

 

Protection item during blasting

1.    A compressed air fed hood

2.    Mask with P2, P3 dust filter

3.    Boiler suit

4.    Ear protection

5.    Long leather gloves and boots

Blasting 효율 매개 변수

Abrasive size, abrasive type, nozzle size, nozzle length, pressure etc…

 

Paint defect

Fish eye

l   Appearance: separation of the wet film, cratering crawling

l   Cause: paint applied on substrate with silicone, oil contamination

l   Repair: solvent wash, sand paper

 

Water spotting

l   Appearance: small or large craters/marks in the shape of large raindrops in the film

l   Cause: water rain falling on an incompletely cured film

l   Repair: solvent wash, sand paper

 

Dirt under paint

l   Appearance: coarse surface texture of the paint film

l   Cause: abrasive, weld spatter, dust e.g. on the steel or between coats in the film

l   Repair: sand down or blast clean and repaint

 

Sag, run, curtain

l   Appearance: narrow, downward movement of paint

l   Cause: too high wet film thickness high thinning, holding the gun too close

l   Repair/ prevent: use of a small brush to correct runs in the wet paint

 

*Sag, run are occurred in partial area / Curtain is occurred in whole area

 

Tar bleeding

l   Appearance: brownish discoloration of topcoat

l   Cause: Tar-containing paint over coated

l   Repair&Prevent / repair: bleeding inhibiting sealer (epoxy mastic, with aluminium or PVA)

 

Popping /cratering

l   Appearance: paint applied on porous substrate (Zinc silicate or thermal sprayed metallic coating)

l   Cause: air and solvent vapor bursting through the wet paint film, solvent in paint displaces the air in the porous undercoat.

l   Repair: sand down to smooth the surface and repaint

 

*Tie coat: one separate coat (20-30㎛) due to avoid popping

*Mist coat: two passes with the gun

1. Pass-very thin (20㎛)
2. Pass-80㎛ coat (within 5-10min) due to avoid popping in a full coat

Pinhole

l   Appearance: tiny hole, deep down in the paint film.

l   Cause: porosity in previous coating film or substrate hot steel temperature

l   Repair: Sand down to smooth surface and repaint

 

Wrinkling

l   Appearance: rough, crinkled surface

l   Cause: very high film thickness, even more at low temperature, solvent attack, e.g MEK

l   Repair: adjust temp. and  Sand down to smooth surface and repaint

 

Blushing

l   Appearance: finish with a flat, milky appearance

l   Cause: condensation on surface, high relative humidity

l   Repair: sand down and apply new topcoat

 

Amine sweating

l   Appearance: sticky, tacky substance providing an unwanted layer on the surface of the dry coating

l   Cause: curing of the original in a low ambient temp. or in a high humidity environment

l   Repair: wash with clean fresh water, worst case slovents

 

Blistering / Void

l   Appearance: small swelled bubble or blistering in the paint film.

l   Cause: paint applied on surface with soluble salt contamination, solvent trapped under the skin of the dried paint

l   Repair/prevent:

ü  Degrease the surface properly prior to painting

ü  Dry surface-check the temp. before painting

ü  Use a slower evaporating solvent during hot  weather

ü  Sand down to smooth the surface and repaint

 

Mud cracking

l   Appearance: irregular cracking that occurs as the paint cures/dries.

l   Cause: highly pigment point (e.g zinc silicate), excessively thick application, tension stress

l   Repair: blast cleaning to Sa 2.5 and reapplication of the inorganic zinc rich coating in correct film thickness

 

Saponification

l   Cause: reaction between oil (in alkyd) and the alkaline substance forming a soap.

l   Exposed to alkaline environment

 

Pinpoint rust

l   Appearance: rusting at pinhole

l   Cause: surface profile too high , voids in film due to pinholes, voids, holidays

l   Repair: Sand down or re-blast and repaint

 

Chalking

l   Appearance: loose powdery material on surface

l   Cause: sunlight /UV expose, breakdown of binder molecules in the very top layer

l   Repair: sand down surface in affected area and repaint

 

Peeling

l   Appearance: poor or no adhesion at all

l   Cause: surface contamination not removed, specified over coating interval not followed.

l   Repair: remove paint down to sound paint coat or to the substrate and recoat

 

Orange peel

l   Appearance: finely pebbled or dimpled surface texture

l   Cause: rapid solvent evaporation, gun too close to the surface, Improper atomization due to low air pressure

l   Repair: Sand down to smooth surface and repaint

 

Lifting

l   Appearance: raising of the undercoat

l   Cause: solvent in top attacks the previously applied film, distortion, blistering or formation of a wrinkled finish

l   Blast cleaning to Sa2.5 and reapplication of the paint

 

Checking

l   Appearance: small breaks in the paint surface

l   Cause: applied/cured at too high a temperature, insufficient dry time prior to recoating

l   Repair: Sand down or sweep and maintain

 

Over spray

• Appearance: rough, porous surface texture, with a sandpaper-like finish. Inorganic zinc coating;other types of coatings.
• Cause: improper atomization; gun too far from the surface, high air temperature and low humidity(rapid solvent evap.)
• Repair:

ü  Zinc ethylsilicate primers – remove dust, worst case blast and re-apply

ü  Physical curing paints – new coat or apply thinner on the surface(messy)

ü  Oxidative curing paints – remove dust and apply a new topcoat

 

Adhesion failure

l   Contamination on the substrate or between coats

l   Incompatible coat

l   Poor surface preparation

l   Max recoating interval exceeded

 

Cohesion failure

l   Improper cure, solvent retention

l   Water mixed into paint, tensile stress

l   Too high DFT, high temperature during drying or curing.

 

Important standards for surface preparation

What is purpose of ISO?

l   To facilitated international trade by providing a standard that people everywhere world recognizing on respect.

 

ISO 8501-1: preparation of steel substrates before application of paints (그림만 그리면 됩니다.)

Rust grade	Hand/power tool		Blast cleaning				Flame
A	-	-	-	-	Asa2.5	Asa3	A Flame
B	Bst2	Bst3	Bsa1	Bsa2	Bsa2.5	Bsa3	B Flame
C	CSt2	Cst3	Csa1	Csa2	Csa2.5	Csa3	C Flame
D	DSt2	Dst3	Dsa1	Dsa2	Dsa2.5	Dsa3	D Flame
4	3	3	3	3	4	4	4

 

Rounding of edges R2mm이유?

Can even film build on edge (if no Rounding of edges R2mm – very low film build on edge) 그림 그리면 좋음.

 

Rust grade

A: completely covered with adherent mill scale: little or no rust visible

B: completely with both mill scale and rust

C: completely covered with rust: little or no pitting visible

D: completely covered with rust: pitting visible

 

Preparation grade

Sa1: light blast cleaning

Sa2: through blast cleaning

Sa2.5: very through blast cleaning

Sa3: blast cleaning to visually clean steel

 

Hand tool and power tool cleaning

St2: through hand and power tool cleaning

St3: very through hand and power tool cleaning

 

ISO 8502 preparation of steel substrates before application of paints and related products-tests for assessment of surface cleanliness

 

ISO 8502-3(assessment of dust on steel surface prepared for painting) Procedure

1.     Press 150mm of freshly exposed tape on the surface.

2.     Rub the tape with your thumb

3.     Remove the tape from the surface and place it on a board

4.     Compare the tape with photographic reference

5.     Assess the quantity of the dust and the predominating particle size

 

ISO 8502-4(estimation of condensation) -> by using siling hygrometer

1.     Check the thermometers

2.     Saturate wick with water

3.     Whirl the sling hygrometer for approx.20 ~30 seconds

4.     Note first wet bulb, then dry bulb temperature

5.     Repeat the whirling for another 20~30 seconds dry bulb thermometer

6.     Repeat both temperatures measurements

7.     The procedure is continued until the readings on each thermometer is constant

8.     Determine RH and dew point from tables

 

ISO 8502-4 equipment

1.     Water

2.     Sling hygrometer or electronic hygrometer

3.     Dew point calculator

4.     Steel thermometer

5.     Hygrometer charts

 

ISO 8502-6(sampling of soluble impurities – the Bresle method)

1.     Remove the protective paper and the punched out material, place the patch on the surface

2.     Fill the beaker with 15ml of distilled water

3.     Record the conductivity

4.     Retrieve 3ml of the water using the syringe

5.     Inject the water through the outer edge of the patch

6.     Retrieve the water into the syringe, repeat this 4times for about 5minutes

7.     Retrieve and transfer the water from the patch to a suitable vessel for analysis

8.     Subtract the initial conductivity from the measured and multiply by 6 to obtain the value in ㎎/㎡

 

ISO 8503 (surface roughness characteristics of blast cleaned substrates)

 

How is roughness reported by use of ISO 8503 comparator? Rugotest No.3?

Comparator

G-fine

S-medium

    

Rugotest

A	N9	a
B	N10	a

 

*Comparator 와 rugotest no.3의 차이를 이해하고 그림으로 표현 할 줄 알아야 합니다. 그리고reporting를 어떻게 하는지 알아야 합니다. Ex) G-fine, S-medium / A(abrasive) N6(roughness)

 

Procedures for use:

1.     Remove all loose dust and debris from the test surface

2.     Select the appropriate surface profile comparator (either ISO 8503-1 G or S depending on the kind of abrasive used)

3.     Place the coparator against the area of the surface.

4.     Assess the profiles on the comparator that are nearest to the profile on the test surface and from these, determine its grade

5.     Fine/medium/coarse

l   Fine: grit (25~50㎛), shot (25~35㎛)

l   medium: grit (50~85㎛), shot (35~60㎛)

l   Coarse: grit (85~130㎛), shot (60~85㎛)

 

Other methods for assessing the surface roughness of blast-cleaned steel

1. Stylus instrument
2. Testex tape
3. Surface profile gauge
4. Toher comparators – Rugotest No.3

Contamination check of abrasive (ASTM D4940)

1.     ADD 300ml of water to 300 ml of abrasive

2.     Stir for 1min with a stirring rod

3.     Let stand for 8min and then stir again for 1min

4.     Discarding the first 10ml of the filtrate

5.     Determine the conductivity using a conductivity meter

 

High profile surface 와 low profile surface의 장단점

High profile surface

Strength point: good quality, good adhesion

Weak point: high consumption of paint

 

Low profile surface

Strength point: low consumption of paint

Weak point: poor quality, poor adhesion

 

Detecting oil or water in the compressed air (ASTM D4285)

1.     Abrasive valve must be closed

2.     White paper or brown wrapping paper in front of the nozzle

3.     Air is turned on for 1min

4.     Please check paper for presence of oil or water

 

Oil -> spot on the sample paper

Moisture -> wet the paper

 

Determining the presence of non-visible grease or oil contamination

• Water break test
• Ultraviolet light test
• Chalk test

ISO 2808 Determination of film thickness (wet film)

 

Comb gauge procedure

1. Firmly grasp the wet film gauge and place it perpendicular into the fresh, wet coating
2. Remove the wet film gauge
3. Record the wet film thickness at the last tooth covered with paint and the next not covered with paint

ASTM D5162 Discontinuity (holiday) testing of non-conductive protective coating on metallic substrates

Procedures for use (wet sponge)

1. Check the DFT(should not be exceed 500㎛)
2. Check that the instrument works (wet sponge to ground)
3. Attach the earth wire from the instrument to the substrate to ensure good electrical contact
4. Saturate the sponge with tap water
5. Move the sponge over the coating (max 0.3 m/s)
6. Wipe surface to avoid telegraphing

Procedures for use (spark testing)

1. Check the DFT (should not exceed 500㎛)
2. Adjust proper voltage
3. Check the instrument (electrode to ground)
4. Check earth (electrode to steel)
5. Move the electrode over the coating 9max 0.3m/s)

ASTM D4752 Measuring MEK resistance of ethyl silicate (inorganic) zinc-rich primers by solvent rub

Procedure

1. Measure DFT
2. Clean surface for loose zinc dust using tissue
3. Fold cheesecloth and saturate cloth with MEK
4. Rub test area with cloth –stroke 50mm
5. Rub until metal is exposed or 50 double rubs have been completed
6. Evaluate according to standard,5 to 0

ISO 4624 Pull-off test for adhesion

Procedures for use

1. Lightly abrade dolly and substrate
2. Clean dolly and substrate with a dry tissue
3. Mix adhesive / apply to dolly
4. Press the dolly firmly to the substrate
5. Tape the dolly
6. Cut around the dolly
7. Record type of break and MPa

Adhesion failure: failure that occurs between the substrate and fist coat or between two coats and related to improper preparation

• Cohesive failure: failure that occurs within the coating layer and related to formulation of the paint

 

Adjustment (calibration) of a DFT gauge

Procedure:

1.     Place the probe onto the smooth / polished steel and adjust to zero

2.     Select a foil close to the thickness to measure

3.     Place the foil onto the smooth / polished steel and adjust the instrument, so that the DFT of the foil is read on the instrument

4.     recheck step 1~3

 

ISO 2409 Cross cut test

Procedures for use:

1. Carried our test in at least 3 different places
2. Use a tool with a sharp cutting edge(Stanley knife, scalpel)
3. Cut through the coating with uniform pressure
4. Repeat this so that a lattice is formed (6x6 cuts)
5. Brush the lattice lightly and apply an adhesive tape
6. Pull off the tape at an angle as close to 60˚ as possible
7. Examine and compare the cut area with photos in the standard

 

The spacing of the cuts depends on the DFT, above 250㎛ the x-cut test can be used

DFT (㎛)	Spacing of cuts(mm)
0-60	1
60-120	2
120-250	3
>250	X-cut test (ASTM D3359)

 

ASTM D3359 rating scale for x-cut test

• 5A: No peeling or removal
• 4A: trace peeling or removal along incisions or at their intersection
• 3A: jagged removal along incisions up to 1.6mm on either side
• 2A: jagged removal along incisions up to 3.2mm on either side
• 1A: removal from most of the area of the x under the tape
• 0A: removal beyond the area of the x

ISO 4628 1-6 Evaluation of degradation-paints

 

ISO 4628 paints and varnishes-evaluation of degradation of paint coatings-designation of intensity, quantity and size of common type of defects

• Part 1: General principle and rating schemes
• Part 2: Designation of degree of blistering
• Part 3: Designation of degree of rusting
• Part 4: Designation of degree of cracking
• Part 5: Designation of degree of flaking
• Part 6: Designation of degree of chalking

ISO 4628-2 blistering

Blistering quantity	Blistering density	Blistering size
0	None
1	Very few	1
2	Few	2
3	Medium	3
4	Medium-dense	4
5	dense	5

 

ISO 4628-3 rusting

Degree	Rust surface
Ri0	0%
Ri1	0.05%
Ri2	0.5%
Ri3	1%
Ri4	8%
Ri5	40~50%

 

ISO 12944

ISO 12944-corrosion protection of steel structures by protective paint systems

• Part 1: general introduction
• Part 2: classification of environments
• Part 3: design considerations
• Part 4: types of surface and surface preparation
• Part 5: protective paint systems
• Part 6: laboratory performance test methods
• Part 7: execution and supervision of paint work
• Part 8: development of specifications for new work and maintenance

ISO 12944-1 general introduction

In this standard, durability is expressed in terms of three range;

• Low: 2 to 5 years
• Medium: 5 to 15 years
• High: more than 15 years

 

ISO 12944-2 general introduction

Atomospheric environments are classified into six corrosivity categories:

• C1: very low
• C2: low
• C3: medium
• C4: high
• C5-I: very high (industrial)
• C5-M: very high (marine)

 

ISO 12944-2 Classification of environments

Three corrosivity categories for water and soil:

• lm 1: immersion in fresh water
• lm 2: immersion in sea or brackish
• lm 3: buried in soil

 

ISO 12944-5 dry film thickness

If no other is agreed upon:

• The individual measurements shall not be less than 80% of the specified value
• Values between 80-100% of the specified value is acceptable if the mean value is equal to or greater than the specified value
• Maximum dry film thickness shall not exceed 3times the specified dry film thickness

Ex) 300㎛  80%-->240㎛ Values between 80~100% of specified value is acceptable

 

 

 

용어정리

1.     General type: means of binder (determine of properties)

2.     Shelf time: maximum storage time remain in good condition

3.     Pot life: maximum useful time after paint mixed (2-compnents)

4.     Flash point: the minimum temperature at which the mixture of air and solvent

5.     Vapour: can be ignited by a flame or spark

6.     Induction time: relation to two-component paint pre-reaction time

7.     PVC: pigment volume concentration

8.     HSE: health safety environment

9.     QM: the management system ensure pre-defined quality

10.  QA: ensure conformance with the pre-defined quality at selected

11.  Emulsion: stable mixture of liquid and liquid (such as oil, water)

12.  DFT에 미치는 영향: rust, dirt, contamination, edge area, surface roughness, paint film condition, calibration method

13.  WFT에 미치는 영향 : SVR, thinning rate, dead volume

14.  Degreasing: surface cleaning method for the removal of the remaining

15.  Contamination: such as oil, grease by solvent, emulsion

16.  Anchor pattern: shape and roughness

17.  Voc (volatile organic compound) : express the content of solvent and other organic compound in a paint (g/)

18.  Specification: document defining required outcome of given job and what to do in order to achieve this.

19.  Procedure: a detailed description of how to perform the talc called for in the spec’.

20.  Dead volume: the amount of paint needed of fill up for the roughness

21.  Ambient temperature (air temperature):  the maximum content of water vapour possible in the air at a given temperature.

22.  RH: relative humidity

23.  The radio of amount of the water vapor present in a given volume of air at a given temperature and maximum amount of water vapor at a given temperature. 간략히 작성하면 - Humidity present in the air /Absolute humidity

24.  Dew point: the temperature at which the air becomes saturated with water vapour

25.  Way of changing the environmental conditions during blasting /painting

ü  By heating the steel (increases the steel temperature, lowers the RH, but not the water vapour content of the air or the dew point)

ü  By heating of the air and ventilation - Will change both the dew point and relative humidity

ü  By use of dehumidifiers – the water vapour is removed and both the dew point and relative humidity is changed.

26.  Tie coat: provide adhesion between difference type paint

27.  Flash coat: heavily thing fast application

28.  Amine sweat: low temperature ~ slow reaction ~ free amine ~ free amine + condensation

29.  Describe the terms ‘mist coat’ and ‘flash coat’

 

Mist coat : finely atomizazted paint on surface   Flash coat : flash application of paint

 

ü  Heavy diluted or thinned paint vs: 40% 

 

30.  Sealer coat: to prevent pinhole, popping on the porous substrate (like concrete) 목적은 mist coat, flash coat와 같다, 적용부위만 다르게 생각하세요

31.  VOC규제 이유 : reduce outlet of voc into the air , problem of ozone layer

32.  Volume solid: portion of a liquid paint, which is not volatile

33.  Cross-linking: network chain which is made by chemical reaction

34.  Durability: the expected life of protective paint system.

35.  Functionality: number of reaction group in a molecule in order to get polymer formation a functionality of two or more is needed.

36.  Flash rust: rust appearance very fast (exposed very high humidity)

37.  Monomer: monomer is unit structure which can be react with hardener

38.  Polymer: polymer is more unit structure, which can be available to form film mechanism

39.  Loss factor list

40.  Spray pattern, weather condition, and remaining quantity in the can and inside of spray hose, dead volume due to the surface roughness

41.  Dead volume: the amount of paint needed to fill up for the surface roughness (그림 그릴 줄 알아야 됨)

42.  Fingering: due to poor atomization by pressure or tip, applied similar to tiger pattern or human finger

43.  H60: An H60 rating mean structural protection for 120 minutes and insulation from smoke and fire for 60 minutes

44.  Hold paint coating의 작용: corrosion protection, protection of cargo, facilitation of cleaning, abrasion resistance

45.  Hold paint coating이 속건성인 이유: to minimize turn around time between cargoes when maintenance painting is required.

46.  Hold paint의 특별한 특징: grain certification

47.  propeller에 도장을 안 하는 이유 : due to the A/F flaking off from the propeller’s movement

48.  List 5 duties of an inspector: monitoring, advise, survey, witness and reporting.

49.  Mill scale : During milling the red-hot steel get into contact with air and a thin layer is formed on

the surface. This layer is called “mill scale”. Mill scale is brittle and only protect the metal as long as it is intact.

50. NORSK standard purpose: This NORSOK standard gives the requirements for the selection of coating materials, surface preparation, application procedures and inspection for protective coatings to be applied during the construction and installation of offshore installations and associated facilities.

51.  Reference area: Suitable area on structure used to establish a minimum acceptable standard for work. Purpose: To check that data provided by manufacture is correct. To enable performance of coating to be assessed at any time after completion.

52.   normative reference: it must be followed ( mandatory )

53.   informative reference: it can be used ( Not mandatory )

둘 다 specification 이나 procedure 상에 참조를 뜻하는데 normative reference는 반드시 따라야 할 것이고informative reference는 사용 할 수 있는 것을 의미합니다.

52. What is different between Low alloyand high alloy

Low alloy – carbon steel added max.2-3% of the elements. Ex) Cr, Ni, Mo, ….

High alloy - carbon steel added max.15-30% of the elements. Ex) Cr, Ni, Mo,….

53. Specific gravity

ü  Calculation of weight of paint apply

ü  Calculation of weight of liquid paint in the drum

 

 

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