How to maintainKorpsschepen

Contents:

A. Maintenance - Why? When?

B. Planning

C. Surface preparation

D. Paint preparation

E. Application environment

F. Paint application

G. Safety

Practical onboardmaintenance

HEMPEL

All coatings gradually deteriorate.

The degree may depend on:

• Initial surface preparation• The type of coating• The area where it is used

Well planned maintenance willpreserve both the corrosion protec-tion and the desired appearance.

MaintenanceWhy?

Inspection

Early Late

Regular inspection reveals early signsof deterioration.

Repair is simple!

If done before major breakdown,costly refurbishment can be elimi-nated.

MaintenanceWhen?

A Maintenance Why? When?

Records of work executed, conditionreports, paint specification sheetsassist future planning, and paintlocker stock records help to have theright materials available for theongoing program.

Records

Initial defects

ChalkingLoss of gloss

Stage 1 Stage 2

Such a surfaceeasily retains dirt.

Remedy:

Thorough removal of chalked layer(powder) as well as other visiblecontaminants before recoating isabsolutely necessary.

Blisters

Blisters - bubbles in the dry paint.

They may contain liquid and arecreated by localized loss of adhesionand lifting of the paint film.

Probable cause: paint applied overcontamination.

Secondarydefect (A)

Cracking - splitting of the dry paint.

Possible causes:

• Too short recoating intervalbetween coats

• Hard coating applied oversoft coating

• Chemical attack - or• Simply age of the coating

system.

Secondarydefect (B)

Cracking

Flaking/peeling

Flaking - peeling - lifting of the drypaint from the underlying surface.

Possibly caused by application tomoist or otherwise contaminatedsurface.

Secondarydefect (C)

A.2 Maintenance - typical defects

Typicalon boarddamage

Coating is discoloured, charred and/or burnt away.

Hot surfaces (e.g. steampipes).

Typicalon boarddamage

Breakdown, erosion or removal ofcoating through impact or wear fromconstant traffic.

Mechanical damage (e.g. on hatchcoamings or decks).

Typicalon boarddamage

Remedy:

Repair the coating system accordingto the maintenance plan agreedupon.

Typicalon boarddamage

Corrosion

A.3 Maintenance - typical damage

Coating will become discoloured,wrinkled, blistered, cracked, softenedor dissolved.

Chemical attack (e.g. spillage of oilsor solvents).

Corrosion (rust) is the finalstage of coating deterioration.

No protection remains -

B Planning

How much?

What is the problem?

a) Initial defectsb) Secondary defects

The criteria for repair and mainte-nance should be defined as part ofthe ship’s maintenance policy.

Determine and mark out areas with:• Loss of gloss • Flaking• Dirty areas • Chemical attack• Chalking • Heat• Blisters • Mechanical damage• Cracking • Corrosion.

Are they localized? or scattered?

Planning

How many manhours are required for:

• cleaning and surfacepreparation

• application of system• allowance for recoating

intervals

Can work be completed before thearea has to be taken into use again?

Are sufficient quantities of correctqualities available on board tocomplete the task?

When?

Provide protection for electrical orother sensitive equipment to preventdamage from cleaning fluids, dust,grit, paint etc.

Protect!

Adequate light is essential for safetyand for proper cleaning and painting.Holidays and thin areas will beavoided.

Rule of thumb:

If you can read newspaper print, lightis adequate.

Light

Remember DON’Tstart a job of a size which cannot beefficiently done within a fair time withthe resources available.

PLAN INSTEADstep by step in workable stages.

Corrosion Thorough cleaning, then:

Total removal of all corrosion prod-ucts and remnants of old coatingsystem. Apply the specified systemto full thickness while observing therecoating intervals between layers.

B.1 Planning

Thorough cleaning with fresh waterand suitable cleaners such asHEMPEL’S LIGHT CLEAN 99350.

In the case of loss of gloss or chalk-ing a fresh finish coat may be ap-plied.

Contamination and/orinitial defects

How shouldthe defectsbe treated?

Thorough cleaning, then:

Remove defective coating from theaffected areas by power tool grindingand touch up the spots to full coatingthickness of the surrounding area.

Localised secondarydefects

Scattered secondarydefects

Same procedure as above plus onefull finish coat over the total area.

C Surface preparation

Use only solvent cleaning on smallareas (and never on painted sur-faces) and change rags and solventregularly, so that you only use cleanrags.

If the water forms droplets, there isstill oil/grease on the surface.Repeat the cleaning procedure. Thewater must run off in puddles, asillustrated.

Oil and grease

Oil and grease must beremoved from the surfacewith an efficient cleaner,such as HEMPEL’S LIGHTCLEAN 99350 followed byfresh water hosing

Open nozzle abrasive blast cleaningis the best method of surface prepa-ration. However, dusty and contami-nating to adjacent areas.

Recommended use:

Abrasive quality: hard, non-contami-nated. No soft sand!

Abrasive size distribution: 0.2 -1.1mm for general work.

10-12 mm nozzle, not worn out.Distance 30 cm and blasting angle60° - 85° to surface.

Abrasive blasting

Pneumatic or electrical power toolsshould be used.

Compressed air must be free from oiland water.

Make sure not to polish the surfacewith worn out wire brushes.

Salts The final cleaning by fresh waterhosing is important for the removal ofsalts, which will otherwise result inearly breakdown of the coatingsapplied.

Power tools

Wet blasting Wet blasting is often used as itreduces dust contamination. Handleas open nozzle abrasive blasting, butremove sludge before it dries out. Ifpossible, avoid using inhibitors.

Oil/grease on surface

No oil/grease

Vacuum abrasive blasting is far lessdusty and less likely to contaminateadjacent areas than open nozzleabrasive blasting. However, themethod has a low/slow productionrate.

Recommended use:

Abrasive quality: hard non-contami-nated. No soft sand!

Abrasive size distribution:0.2 - 1.1 mm.

Vacuum blasting

Water jetting High pressure water jetting(hydroblast) produces a high velocitywater jet by forcing pressurized (up to30,000 psi) water through a speciallydesigned small orifice nozzle.

The method requires fresh water andspecially trained operators, plusspecial safety precautions for opera-tors and surroundings, i.e. area mustbe cleared for all other personnel.The method is very fatiguing to theoperator.

Use a suitable cleaning agent inconcentrations as recommended bythe supplier.

Chemicalcleaners anddegreasers

Mainly consist of water soluble salts/oils. Again, they may leave solublesalts/soaps.

Therefore, wash with plenty of freshwater afterwards - or even better, donot use them. If you do use them,watch out for contamination ofadjacent areas. If possible, avoidusing any acid or alkali containingmaterials altogether.

In general they contain acid andwill consequently leave solublesalts on the surface which maycause blistering or other typesof failure. Therefore do not useor use only followed by washingdown with plenty of fresh water.

Rust converters/conditioners

Rustinhibitors

C.1 Surface preparation

The types of paint which are typicallyused for shipboard maintenance arenot critical in relation to roughness ofthe surface. However, too highroughness could mean poor paintcoverage over roughness peaks andpinhead rusting.

Roughness

Dust will nearly always be present toa certain extent, but too muchcauses poor adhesion of the coat-ings.

Remove dust by:

a) Vacuum cleaner.b) Clean bristle brush.c) Blowing with dry, clean

compressed air.

Dust removal

An easy check to establish whetherdust has been removed sufficiently is:

Transparent, adhesive tape

Some very small amounts of dust mayremain.

Tape test

Standards are set in order to beachieved. Use the InternationalStandard ISO 8501-1:1988 asreference.

Other prominent standards youmay refer to, are:

• Steel Structures PaintingCouncil - SSPC.

• British StandardsInstitution BS 7079

Find the standard you should achieveand compare the relevant picturewith the actual surface. Check alsothe text and determine if it describesthe actual surface.

For optimum surface preparationrefer to ISO 8501-1:1988 Sa 2½ forabrasive blasting and to St 3 forpower tool cleaning.

Cleanliness

C.2 Surface preparation

D Paint preparation

The products are different! That iswhy there are more than one. Under-stand the special characteristics ofthe product you are about to use.Product Data Sheets and Mainte-nance Sheets contain relevantinformation.

Coatings are chemical compositionsand as such there are directions fortheir safe handling and use. ReadSafety Data Sheets (SDS) whereapplicable.

Before you start to handleor use any coating, learnall that is worth knowingabout the product and thecorrect and safe use of it.

Products/Safety

Ensure that all the coatings arestored under correct conditions, i.e.in a covered store which is dry andventilated and with a suitable tem-perature.

Establish a store/stock systemwhere the products are used on a“first in - first out” basis.

Storage/Housekeeping

If the quantity needed is smaller thanthe quantity supplied, the correctmixing ratio is mentioned on the tin/drum.

Use only the correct ratio - not toomuch and not too little!

Wrong ratio = poor performance.

Mixing

Many of the coatings are suppliedas a BASE and a CURING AGENTin a pre-determined mixing ratio.The components must be mixed inthis ratio.

Do not just paddle in the paint!

Use a mechanical stirrer. Afterstirring, the material should have acompletely uniform colour with nolumps or sediments. Always stir foran extra 30 seconds.

Stirring

Do not thin the paint unless abso-lutely necessary. When thinning, addonly the minimum volume necessaryto obtain a good paint flow and filmformation.

Before thinning always check that thepressure of the spray pump is cor-rect, the filter clean and the spraynozzles not worn out.

Two-component paints must be mixedbefore thinning takes place. Toomuch thinner causes paint “running”and/or solvent “boiling”, i.e. holes inthe paint film and too low paint filmthickness.

Insufficient thinning can cause an“orange peel” effect and, if sprayapplied, spray dust on the surface. Inhot climates extra thinner may benecessary.

Use only thecorrect thinneras mentioned inthe data sheet!

Thinning

Two-component paint must be usedwithin a certain period of time aftermixing of the two parts (= pot-life).The pot-life depends on the tempera-ture - a high temperature shortensthe pot-life. Check the pot-life of theproduct on the data sheet.

NB Thinning will not prolong the pot-life. If the pot-life is exceeded, do notuse the paint. The chemical reactionhas already changed its properties.Discard it!

Pot-life

Zinc primers have heavy pigments!

Therefore, keep stirring to avoidsetting of the heavy part of thematerial.

Keep stirring

D.1 Paint preparation

E Application environment

Too low air temperature will delay thedrying of the paint and it may beginto slide and form “curtains”.

Too high air temperature will causedry spray giving a powdery surfaceand a porous film.

The best temperature for painting is15-30°C/59-86°F.

Air temperature

A high temperature of the steelsurface will result in a too rapidsetting of the paint and thereby aporous coating.

A low temperature of the steelsurface will delay the drying ofthe paint. If a cold item isbrought into a warm workshop,water (condensation) may formon the surface. Therefore, waituntil the steel piece is also warmbefore starting to paint.

Use a steel surface thermometer tocheck the temperature of the surfaceitself.

Steeltemperature

Use a psychrometer and a dew pointcalculator to calculate the relativehumidity and the dew point. Comparethe dew point with the temperature ofthe steel surface.

The temperature of the steel surfacemust be at least 3°C or 5°F abovethe dew point shown on the calcula-tor. The difference in temperaturebetween day/night and night/dayoften causes condensation.

There may be water on thesteel surface because ofcondensation. This will preventadhesion of the paint.

Relative humidity/dew point

Keep ventilators clean and in workingorder. When ventilating rooms orconfined spaces there should be aslight overpressure to keep dust fromentering the space.

Ventilation does not substitute theuse of an air fed hood/mask or dustcartridge respirator. Where the latteris used, replace the cartridge regu-larly. Follow prevailing safety regula-tions.

Ventilation

F Paint application

A brush is a slow, but very goodapplication tool, especially forareas difficult to spray.

Use a good quality brush anduse it for stripe coating onwelding seams, on all sharpedges and on areas difficult tospray before applying full coatswith e.g. airless spray.The brush-applied coating willpenetrate into rough surfaces(weld seams) and by “laying” onthe paint on critical areas suchas sharp edges, a better protec-tion is achieved.

Rollers are only suitable for applyinga cosmetic coat on an already wellprotected surface. If rollers must beused for application of rust preven-tive primers and intermediate coats,apply evenly without “stretching” thepaint.

Several (2-4) coats may be necessaryto substitute one coat applied byspray.

Manualmethods

Airless spray is the fastest and mostefficient method of application ofcoatings.

Check the following when usingairless spray:

• That the spray pump has enoughvolume, output pressure andcapacity.

• That the nozzle size and fan widthare correct for the paint type.

Check the product data sheet!

Sprayingmethods

Special attention must be paid toareas difficult to reach and coat.

These includes:• all sharp edges• welding seams• corrugated areas• behind bulb angles• behind hand rails• mouse holes• underside of coamings• etc. etc.

Stripe coating and extra coats onsuch spots are a must for profes-sional, long-lasting protection.

Special attentionareas

Air spray provides a lowerproduction rate and more spraydust than airless spray. Only lowthicknesses can be applied,even of high-build products.Therefore, air spray is generallyonly recommended as a touch-up/repair tool for minor areas.

If the coats are applied too quicklyafter each other, running, sagging,solvent retention and insufficientcuring may occur. If they are appliedafter too long intervals, they may notstick/adhere to each other.

Before starting to coat, i.e. whenplanning the job, check the datasheets of all the products to beused. Find out about the minimumand maximum recoat intervals andtake them into consideration.

Overcoatingintervals

Uneven movements duringapplication will result in anuneven paint film. This canresult in:

• paint running• paint sagging• porous coat• undercoated areas/

holidays

Experienced/trained paint applicatorsavoid these problems which aredifficult to fix and which can becostly.

Use a systematic method of sprayingthe paint from the correct distance(approx. 30 cm/1 ft). Use a wet filmcomb during application in order todetermine that a correct and evenwet film is obtained. It is far easier tocorrect uneven film during applicationthan later on, as later correctionsmay be visible.

Applicationtechnique

Apply the paint evenly!

As the same application tools (spraypumps, guns, brushes etc.) may beused for different types and coloursof material, they should always bekept clean.

Clean tools give better results!

Clean the tools in the thinner or toolcleaner recommended for the particu-lar product. Do not use a tool cleaneras thinner!

Cleaning oftools

F.1 Paint application

A too low thickness means earlyrusting. Therefore additional coatsmay be required if target thickness isnot met initially.

A too high thickness means over-consumption of material and thepossibility of the coatings not dryingbut remaining soft.

The best and most accurate instru-ment is the latest models of digitalinstruments with memory. All instru-ments must be adjusted properlybefore use.

D.F.T. control

It is the final quality assur-ance check of the total dryfilm thickness (D.F.T.) tomeasure that the correctthickness has been applied.

Keep all fences and warning signsposted until the coatings are com-pletely dry and tolerate general traffic.

Keep fences

When the coating job is finished donot just leave the site. Maintainventilation and/or heating to ensurethat the coatings dry and cure in theproper manner.

Correct dryingand curing

Temperature has a great influence onthe behaviour of the paint, bothduring application and drying/curing.

In cold weather, paint gets thickerand more difficult to spray. It alsodries and cures more slowly. It isalways better to heat the paint thanto thin it down. Preferably, the tem-perature of the paint should be 15-25°C/59-77°F during application.

In warm weather, paint gets thinner,but tends to dry spray. Extra thinningmay be necessary.

The pot life of two-component prod-ucts is shorter. The temperature ofthe steel should not be above 40°C/104°F during application.

Temperature

F.2 Paint application

G Safety

Material safety equals -

A paint store which is clean, tidy andorderly.

Tins stored and stocked so that theydo not turn over and leak.

Lids covering tins containing coatingsor solvents.

Watch out for fumes and ventilate ifnecessary.

Product Data Sheets and Safety DataSheets are to be kept accessible andup-to-date.

Materials safety

Airless spray must always be earthedas static electricity can developwithin the system and be the causeof explosion.

All couplings must be of a close fit,especially on high pressure equip-ment.

Replace damaged hoses.

During airless spraying the paint isunder an immense hydraulic pres-sure. Release of the pressurethrough the spray gun or any leaks ofthe equipment is dangerous, and astream of paint may easily penetratehuman skin, in which case immediatemedical aid is required.

Equipment safety

Minimize contact of paint with yourskin.

Cover as much as possible withsensible working clothes.

Wear gloves and eye protection.

Consider the use of a suitable barriercream on exposed skin.

Use air fed hood/mask or respiratorin confined spaces.

Ensure safe access and adequatelighting.

Tidy up as you proceed - good house-keeping contributes to safety.

Respect safety regulations.

Personal safety

On site safety can be enhanced bysmall measures, such as:

• non-skid/slip coatings onwalking areas

• high visibility coatings tomark danger zones

• tidy and clean surfaces ingeneral

• immediate removal ofspillage.

Job site safety

Never allowNaked flames - matches - cigarettes -in the same area where paint isbeing applied or stored.

AlwaysThoroughly ventilate any area wherepaint is spilled. Clean up immediatelyand dispose of the cleaning materialin a closed metal container.

AndIf fire should occur, do not attempt toput it out with water - use powder orcarbon dioxide (CO2) fire extinguish-ers.

Most paints containflammable solvents.

Fire hazard

G.1 Safety