C5-Slides

Steelwork

Paint School

Most coating failures result from poor or inadequate: •

Steel preparation

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Cleaning

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Surface preparation

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Application

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Access

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Ventilation

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Coating selection

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Inspection and control

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Premature exposure (Exposed too soon)

Paint School

Investigation by a Guarantee Insurance company has shown:

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95 % of all coating failures result from  – Poor surface preparation  – Poor application

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85 % of all failures appear within 1-2 years

This fits in well with our own experience

Paint School

Steelwork preparation involves the following activities Rounding or smoothing of:

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Sharp edges Corners Welds

Grinding of:

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Laminations Flame cut edges Weld spatter

Notches minimum diameter: 30 mm Inspected and approved before cleaning See ISO 8501 “V “Visual isual assessment of surface cleanliness” Paint School

Steelwork preparation

Rounding sharp edges Coating applied to a square-cut section Sharp edge Reduced coating thickness at sharp edges due to tension created during drying / curing

Coating

Steel

Paint School

Rounded edge Even coating thickness

Manholes in a Tank •

Section manholes

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Well grinded edges Cd-4932-13

Paint School

Weld with pinhole. Visible through the paint system • •

Will lead to initiation of corrosion Remedial actions: Remove the paint, re-weld and grind. Apply  paint

NOTE: Such defects may  be difficult to find during inspection

Paint School

Cd-4930-42

Early corrosion on sharp edge and spot welds •

Paint has newly been applied

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Exposed to wind and weather for approximately 2 weeks

Cd-4930-78

Paint School

Severe corrosion due to a combination of several effects •

Sharp edges

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Rough welds (not grinded)

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Missing stripe coating

Cd-4930-71

Paint School

Construction after steelwork preparation.

Grinded edge and weld

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•

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Sharp edge has been rounded Welding flux and smoke has  been removed Grinded weld  bead

Paint School

Cd-4932-15

Construction with sharp edge, weld flux and weld beads Pre-blasting preparation to be carried out: •

Round sharp edge

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Remove welding flux with water

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Grinding of weld bead Cd-4932-14

Paint School

Steel preparation

Weld spatter, welding smoke

Weld spatter

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Weld Areas at risk

Small weld spatters Even only one small weld spatter may be sufficient to initiate corrosion which with time may lead to severe problems

NOTE: Small failures like this are difficult to find

Paint School

Cd-4930-45

Unacceptable weld.

Too rough and full of pinholes/pores Weld spatters close to weld

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Re-welding and grinding must be carried carri ed out  prior to re-blasting and painting

Cd-4930-39

Paint School

Paint on a very poor weld.

Pinholes and holidays visible after second stripe coating •

 Neither re-welding nor grinding have been carried out prior to application

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Remedial Actions: Re-blasting, re-welding, grinding and blast -cleaning: COSTLY

Cd-4930-41

Paint School

Early corrosion of welds in a water ballast tank •

Rough weld seams. Should have been grinded

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Probably in combination with  poor stripe coating

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Mud can be seen,  particularly on the  bottom

Paint School

Cd-4930-75

Inside a tank after good steelwork and paint application Steelwork preparation and application of the paint have  been carried out well

Cd-4930-51

Paint School

Steel support after good steelwork and paint application Pre-blasting preparation and application of the paint have been carried out well

Cd-4930-52

Paint School