Surface Preparation Book

SURFACE PREPARATION GUIDE BOOKLET RUST GRADES OF STEEL / GRADES OF BLAST CLEANED STEEL

COMPARABLE GUIDE TO BRUSH-OFF, SSPC-SP7 (NACE NO 4 / SA 1)

Very light whip blast clean with removal of loose surface contaminants.

COMPARABLE GUIDE TO COMMERCIAL, SSPC-SP6 (NACE NO 3 / SA 2)

Substantial blast clean with wide spread, visible contaminant removal and base metal colour.

COMPARABLE GUIDE TO NEAR-WHITE METAL, SSPC-SP10 (NACE NO 2 / SA 2½) Intense blast clean leaving shaded grey metal with only tiny, isolated flecks or strips of visible contaminants.

COMPARABLE GUIDE TO WHITE METAL, SSPC-SP5 (NACE NO 1 / SA 3)

Complete blast clean with consistent, metal colour all over and no visible contaminants.

RUST GRADE A

Steel with the mill scale layer intact and very minor, or no rusting.

UNBLASTED

This condition cannot normally be attained when removing adherent mill scale

Comparable to BRUSH-OFF, SSPC-SP7 (NACE NO 4 / SA 1)

Comparable to COMMERCIAL SSPC-SP6 (NACE No 3 / SA 2)

Comparable to NEAR-WHITE METAL SSPC-SP10 (NACE No 2 / SA 2½)

Comparable to WHITE METAL SSPC-SP5 (NACE No 1 / SA 3)

COMPARABLE GUIDE TO BRUSH-OFF, SSPC-SP7 (NACE NO 4 / SA 1)

Very light whip blast clean with removal of loose surface contaminants.

COMPARABLE GUIDE TO COMMERCIAL, SSPC-SP6 (NACE NO 3 / SA 2)

Substantial blast clean with wide spread, visible contaminant removal and base metal colour.

COMPARABLE GUIDE TO NEAR-WHITE METAL, SSPC-SP10 (NACE NO 2 / SA 2½) Intense blast clean leaving shaded grey metal with only tiny, isolated flecks or strips of visible contaminants.

COMPARABLE GUIDE TO WHITE METAL, SSPC-SP5 (NACE NO 1 / SA 3)

Complete blast clean with consistent, metal colour all over and no visible contaminants.

RUST GRADE B

Steel with spreading surface rust, and the mill scale commenced flaking.

UNBLASTED

Comparable to BRUSH-OFF, SSPC-SP7 (NACE NO 4 / SA 1)

Comparable to COMMERCIAL SSPC-SP6 (NACE No 3 / SA 2)

Comparable to NEAR-WHITE METAL SSPC-SP10 (NACE No 2 / SA 2½)

Comparable to WHITE METAL SSPC-SP5 (NACE No 1 / SA 3)

COMPARABLE GUIDE TO BRUSH-OFF, SSPC-SP7 (NACE NO 4 / SA 1)

Very light whip blast clean with removal of loose surface contaminants.

COMPARABLE GUIDE TO COMMERCIAL, SSPC-SP6 (NACE NO 3 / SA 2)

Substantial blast clean with wide spread, visible contaminant removal and base metal colour.

COMPARABLE GUIDE TO NEAR-WHITE METAL, SSPC-SP10 (NACE NO 2 / SA 2½) Intense blast clean leaving shaded grey metal with only tiny, isolated flecks or strips of visible contaminants.

COMPARABLE GUIDE TO WHITE METAL, SSPC-SP5 (NACE NO 1 / SA 3)

Complete blast clean with consistent, metal colour all over and no visible contaminants.

RUST GRADE C

Rusty steel with the mill scale layer flaked and loose, or lost, but only minor occurrence of pitting.

UNBLASTED

Comparable to BRUSH-OFF, SSPC-SP7 (NACE NO 4 / SA 1)

Comparable to COMMERCIAL SSPC-SP6 (NACE No 3 / SA 2)

Comparable to NEAR-WHITE METAL SSPC-SP10 (NACE No 2 / SA 2½)

Comparable to WHITE METAL SSPC-SP5 (NACE No 1 / SA 3)

COMPARABLE GUIDE TO BRUSH-OFF, SSPC-SP7 (NACE NO 4 / SA 1)

Very light whip blast clean with removal of loose surface contaminants.

COMPARABLE GUIDE TO COMMERCIAL, SSPC-SP6 (NACE NO 3 / SA 2)

Substantial blast clean with wide spread, visible contaminant removal and base metal colour.

COMPARABLE GUIDE TO NEAR-WHITE METAL, SSPC-SP10 (NACE NO 2 / SA 2½) Intense blast clean leaving shaded grey metal with only tiny, isolated flecks or strips of visible contaminants.

COMPARABLE GUIDE TO WHITE METAL, SSPC-SP5 (NACE NO 1 / SA 3)

Complete blast clean with consistent, metal colour all over and no visible contaminants.

RUST GRADE D

Steel with spreading surface rust, and the mill scale commenced flaking.

UNBLASTED

Comparable to BRUSH-OFF, SSPC-SP7 (NACE NO 4 / SA 1)

Comparable to COMMERCIAL SSPC-SP6 (NACE No 3 / SA 2)

Comparable to NEAR-WHITE METAL SSPC-SP10 (NACE No 2 / SA 2½)

Comparable to WHITE METAL SSPC-SP5 (NACE No 1 / SA 3)

THE DIFFERENCE BETWEEN SURFACE PROFILE AND CLASS OF BLAST THERE IS A BIG DIFFERENCE BETWEEN SURFACE PROFILE AND CLASS OF BLAST Surface Profile is the ‘shape’ of the surface finish (and measuring the size of the ‘shape’ created). Class of Blast however, is the ‘cleanliness’ of the surface finish. In other words, the Class of Blast is what degree the rust, paint and/or other contaminants have been removed.

While both the Surface Profile and the Class of Blast are very important characteristics of the surface finish, they are different characteristics, and should be separately specified when planning to blast a surface to a ‘ready to coat’ stage.

SURFACE PROFILE

UNBLASTED SMOOTH SURFACE

BLASTING

BLASTED PROFILED SURFACE

With the abrasive blasting process, grains of abrasive are propelled with great force and energy at the substrate. On impact, the grains dig into and then rebound out and off the surface leaving a rugged, miniature ‘mountain - and - valley’ finish – a profile.

Surface Profile is critical to coating performance by: • increasing the surface area (more chance of adhesion).

• providing a ‘key/anchor pattern’ for the coating to lock in and adhere to.

While a ‘too small’ profile can be detrimental to coating adhesion, it can be equally disastrous to have an excessive profile height, causing premature rusting and coating failure.

It also follows that a larger profile means using more paint to cover the surface, hence more cost!

Another issue is embedment – abrasive particles caught in the surface cavities from blasting. This is mainly caused by friable and irregular shaped abrasives. The embedded particles or fragments, can stand out as ‘rogue’ peaks above the surrounding profile and protrude through the applied coating. Only a hard, regular shaped abrasive should be used for this reason.

FIND OUT YOUR SURFACE PROFILE WITH STEP 1 – TEST PREPARATION

STEP 2 – PERFORM THE TEST

STEP 3 – MEASURING RESULT

TESTEX TAPE Getting a correct surface profile (also known as roughness) is vital for achieving long lasting coatings.

Stop nasty surprises Excessive or insufficient profile height can cause rapid coating failure, hassles with paint inspections and dissatisfied clients.

PROOF OF QUALITY Testex Profile Kits are an ideal quality control, allowing you to keep permanent job records if required and providing valuable proof for paint inspectors.

Each kit contains a roll of Testex Profile Tape, a burnishing tool and a precision dial thickness gauge, which allows quick, accurate measurement of surface profiles to within 5 microns (0.2 mils).

CLASS OF BLAST The Class of Blast is simply how much the surface has been cleaned – how much effort, time and money does the customer want to spend, versus the extent of the cleaned finished surface required.

RUST GRADE B

Steel with spreading surface rust, and the mill scale commenced flaking.

UNBLASTED

BLAST CLASS SSPC-SP6/COMMERCIAL

In the example above, it was established by the blasting contractor and agreed by the customer that the original surface presented was Rust Grade B. This was easily established by using the Surface Preparation Chart. The customer has then stipulated that a Blast Class SSPC-SP6 is required. A costing is agreed to and both parties feel that they are confident in knowing what finish is to be expected.

HOSE SELECTION GUIDE FOR BLASTING AT 100 PST NOZZLE PRESSURE Nozzle Number

No 4

No 5

No 6

No 7

No 8

Nozzle Size

1/4” 6mm

5/16” 8mm

3/8” 10mm

7/16” 11mm

1/2” 13mm

CFM at 100 psi

103

158

229

312

407

L/s at 6.9 bar

49

75

108

147

192

Air Hose ID - Minimum

25mm 1”

38mm 1 1/2”

38mm 1 1/2”

50mm 2”

50mm 2”

Blast Hose ID - Minimum

20mm 3/4”

25mm 1”

32mm 1 1/4”

32mm 1 1/4”

38mm 1 1/2”

‘Hold your Class of Blas

During abrasive blasting and immediat is a critical factor, as the blasted surfa corrosion – flash rusting. The electrol ‘HOLD YOUR CLASS OF BLAST’ is usuallyafter, the water in the air – reduce During abrasive blasting and immediately the Relative decreases greatly.

You could then Ho Humidity is a critical factor, as the blasted surface becomes

vulnerable to corrosion – flash rusting.

The electrolyte in Dehumidification atmospheric corrosion is usually the water in the air – reduce A Dehumidifier will reduce the this and the problem decreases greatly. You could then hold water content in the air and the your Class of Blast. next stage of the process can be ‘put on hold’ until all the blasting DEHUMIDIFICATION is completed. Using this dry air, a painting job inside a large tank A Dehumidifier will reduce the water forofexample, can be done without content in the air and the next stage stop/starting and this would also the process can be ‘put on hold’ until all the blasting is completed. Usingassist in reducing the drying time of this dry air, a painting job inside a large You must have Dry Air tank for example, can be done without stop/starting and this would also assist To remove moisture from warm comp in reducing the drying time of the coating. the air sufficiently to allow the water va droplets. Water droplets can then be r

YOU MUST HAVE DRY AIR The AirPrep™ system efficiently remo

To remove moisture from warm drop in compressed air pressure (eve nozzle decreases production by 15% compressed air, you must first cool the air sufficiently to allow the The air exits cooler, cleaner and Drie water vapour to condense into water droplets. Water droplets can then be removed from the air. The AirPrep™ system efficiently removes moisture with negligible drop in compressed air pressure (every 10% psi lost at the nozzle decreases production by 15%!).

THE AIRPREP IS AN The air exits cooler, cleaner and drier INTEGRAL PART OF A GOOD to your Blasting System.

BLASTING SYSTEM The AirPrep is an integral part of

INCREASE YOUR EFFICIENCY USING DRY AIR! Increase your efficiency using Dry Many blasters who use AirPrep™ Moisture Removal Systems

blasters who AirPrep™ Mo find that cool, dry compressed airMany actually blasts up use to 15% thattocool, dry compressed air actually faster! Dry air makes it much easier control your abrasive flow. You almost never need to choke Blast itMachine again.

Dryyour air makes much easier to contr

ABRASIVE METERING

almost never need to choke your Bla

Abrasive Metering

Don’t waste valuable abrasive – Make sure your abrasive Don’t valuable – Mak metering valve is set properly. How can waste you tell?

Look abrasive at valve is set An properly.

Howair/ can you tel the abrasive flow coming out of your nozzle. efficient coming out of your nozzle. abrasive mixture will be only slightly visible, appearing as aAn efficien coloured haze in the air stream. only slightly visible, appearing as a co

you seetoo a lot of colour in this flow, th If you see a lot of colour in this flow,Ifthere’s much abrasive enough air) in the mixture. W (and not enough air) in the mixture.(and Why?not Your abrasive metering valve is open too far.efficiency When this happe valve is open too far. When this happens, your cleaning is lowered, valuable abrasive is lowered, valuable abrasive is wasted and you’re losing money.is waste Create the best mixture by starting off with no abrasive and slowly open up the metering valve, until you can only just start to see the colour change in the air exiting the nozzle. That’s all the abrasive you need for fast and efficient blasting.

Cre star slow valv star the all t fast

Nozzle Size

Efficiency

PSI (bar)

AIR CONSUMPTION CFM (L/S) PER BLAST NOZZLE (USING GARNET ABRASIVE)

No 2 1/8”

No 3 3/16”

No 4 1/4”

No 5 5/16”

No 6 3/8”

No 7 7/16”

No 8 1/2”

No 10 5/8”

No 12 3/4”

50 (3.4)

14 (7)

32 (15)

57 (27)

89 (42)

129 (61)

176 (83)

229 (108)

356 (168)

516 (244)

41%

60 (4.1)

17 (8)

37 (18)

66 (31)

103 (49)

149 (70)

203 (96)

265 (125)

412 (194)

596 (281)

55%

70 (4.8)

19 (9)

42 (20)

75 (35)

117 (55)

169 (80)

230 (109)

300 (142)

468 (221)

676 (319)

64%

80 (5.5)

21 (10)

47 (22)

84 (40)

131 (62)

189 (89)

258 (122)

336 (159)

524 (247)

756 (357)

74%

90 (6.2)

24 (11)

52 (25)

93 (44)

145 (68)

209 (99)

285 (135)

371 (175)

580 (274)

836 (395)

86%

100 (6.9)

26 (12)

57 (27)

103 (49)

158 (75)

229 (108)

312 (147)

409 (192)

632 (298)

916 (432)

100%

120 (8.3)

30 (14)

67 (32)

119 (56)

186 (88)

269 (127)

367 (173)

478 (226)

744 (351)

1076 (508)

130%

140 (9.7)

34 (16)

77 (36)

136 (64)

214 (101)

309 (146)

422 (199)

549 (259)

856 (404)

1236 (583)

165%

*For pressures 120 psi (8.3 bar) and above – ensure equipment is rated accordingly.

WORK UNDER PRESSURE CHECK NOZZLE PRESSURE FOR PRODUCTIVITY Use a hypodermic needle pressure gauge kit. Insert the needle into the blast hose slowly, about 3” (75mm) back from the nozzle. Point the needle toward the nozzle, at a slight angle. Insert slowly until you get a constant reading. Are you getting 100psi?

CH

EC

K

K

EC

CH

CHECK

NOZZLE PRESSURE TEST KIT

Check your Blasting system right through and find where your pressure losses are located.

Test the pressure at both ends of a long length of hose – you’ll be amazed to see how much pressure can drop! We recommend getting two pressure test kits, to test air going into your blast pot versus air pressure coming out. If you are losing excessive pressure, it may be equipment, accessory or compressor related.

Typical equipment used in the Surface Preparation and Coating industry.

CM CM

INCHES INCHES 6

0 1

Paint Spraying Equipment

2

Abrasive Blasting Packages

5 BLASTONE INTERNATIONAL GLOBAL LOCATIONS

3

AUSTRALIA

4

Adelaide | Brisbane | Darwin | Mackay | Melbourne | Perth | Sydney

Safety Equipment

Coating Thickness Instruments

6

NEW ZEALAND

5

4

Phone 1800 190 190 Email sales.au@blastone.com

Auckland | Christchurch Blasting Equipment

Email sales.nz@blastone.com

8

NORTH AMERICA

7

Phone 0800 100 493 Mobile Dust Collectors

3

Columbus | Los Angeles | Minneapolis

9

Phone 1800 999 1881 Email sales.us@blastone.com

Dehumidifiers

Blast Rooms

UNITED KINGDOM IMPORTANT NOTE: London Surface cleanliness is not a measure of surface profile.

12

www.blastone.com

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Note: All blasting preparation grades must be free of oil, grease and dirt.

PhoneThe 0845 381 2000 Disclaimer: grades of rust and blast cleaned surfaces ‘information’, described andsales.uk@blastone.com illustrated in this booklet are a guide only and do not claim to Email be approved nor complying nor substitutable for or by any surface preparation standard. It is the responsibility of the reader and/or users of this ‘information’ to separately determine and verify the specifications and/or methods and/or assessments of surface preparation as indicated or directed or required by or in any work specifications or standards. Blast-One expressly disclaims any liability for the use or misuse of this ‘information’.

10

2 1

14 15

0

IMPORTANT NOTE

North American Telephone (614)of476-3000 Surface cleanliness is not a measure surface profile. region Fax (614) 476-6939

Note: all blasting preparation grades must be free of oil, sales@blast-one.com grease and dirt. Email Disclaimer: The grades of rust and blast cleaned surfaces

‘information’, and illustrated this booklet Australia and described Telephone +61 8in8292 2000 are a guide only and do not claim to be approved nor complying Asianor Pacific Fax +61 8preparation 8292 2001 substitutable for or by any surface standard. It is the responsibility of the reader and/or users region Email sales.au@blast-one.com of this ‘information’ to separately determine and verify the

specifications and/or methods and/or assessments of surface UK preparation & Europeas indicated Telephone +44or845 381by2000 or directed required or in any region +44 845 expressly 381 2001 work specificationsFax or standards.

BlastOne disclaims any liability for the Email use or misuse of this ‘information’. sales.uk@blast-one.com © BlastOne 2016

Web

B3051

www.blast-one.com © Blast-One International 2011

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