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topic 12526

Sand blasting standards: Swedish SA 1, SA 2, SA 2.5, SA 3 vs. NACE and Ra


A discussion started in 2002 but continuing through 2018

2002

Q. I need to know the technical details about the following- Surface preparation - Cast Iron part (gratings, used for cooking ranges); the surface needs to be prepared by sand blasting as per Swedish Standard, SA 2.5 or better as per Swedish Standard, SA 3. If it is possible then please inform about the surface finish value (Ra, Rmax) which can be achieved by the above mentioned process.

Please respond as early as possible.

Best Regards,

Souren Pal
steel company - Ahmedabad, Gujarat, India
similarly 2002

Q. Dear Mr. Souren Pal,

I am also interested in the relationship between the SA standards SA 1, 2 2.5 and 3 and Ra. An interesting answer on your question which may be of help to me?

Best Regards,

Laure Spriensma - Jirnsum, The Netherlands

2003

Q. I WOULD LIKE TO INQUIRE INFORMATION REGARDING SAND BLASTING PROCEDURES, EQUIPMENTS AND MATERIAL, AS DESCRIBED IN SWEDISH STANDARD SA1, 2, 2.5, 3? YOUR COOPERATION ON THIS MATTER WILL BE HIGHLY APPRECIATED.

FADI MUSALLAM - ABU DHABI, UAE

Surface Preparation and Finishes for Metals
from Abe Books

or


Surface Preparation ISO 8504-2:2000
from Techstreet

or

2004

A. Mr. Souren Paul , Laure Spriensma, Mr. FADI MUSALLAM,

Surface preparation standards are stipulated by various bodies throughout the world to designate the cleanliness condition of blasted steel, prior to applying a protective coating. The applicable cleanliness standard is usually called for by either the protective coating manufacturer or the owner of the structure to be painted. The most commonly referred to standards are SSPC, NACE, and Swedish Standards. Each standard is divided into four standards of cleanliness, broadly described as follows; brush off, commercial, near white metal, white metal. Whilst each standard may differ slightly in requirements and terminology the following cross reference chart indicates the close approximation of each level of cleanliness for each standard.

A brief description of each of the four levels of cleanliness is as follows:

I hope the above info is useful to you. We are setting up a shipyard and are installing a plate preparation shop.

Regards,

Bijit Sarkar
shipbuilding - Calcutta, WB, India


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2007

Q. May I know the surface profile difference between SA 2.5 and SA 3 in microns?

Shahaji Doltade - UAE

February 17, 2012

A. Dear Mr. Shahaji Doltade
We know that sa 2.5 & sa3 are cleanliness levels not Roughness levels.
Regards

Sohail-Hashmi - Karachi,Pakistan

March 19, 2010

Q. Dear sir,
I want to know about measuring instrument for surface finish SA 2.5. I also want to know about from which size of grit we can achieve surface finish SA 2.5.

Your sincerely

PRASHANT KUMAR GUPTA - student - ROHINI, DELHI, INDIA

March 19, 2010

A. Hi, Prashant. The above discussions lead me to believe that Sa2.5 is not a "surface finish" but a visual standard for cleanliness and is not related specifically to grit size and surface roughness standards like Ra / Rz, and it cannot be measured with a profilometer. Do you have a copy of ISO 8501-1 handy, with its description of Sa2.5? Thanks.
Regards,

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey


May 5, 2010

Q. Thanks for the information that SA 2.5 is not measurable in Ra, but we have seen specifications, such as in containers manufacturing that surface finish to SA 2.5 to achieve 25 to 30 micron finish. Is it correct!

S P S DHINGRA
- Kolkata, India
May 5, 2010

A. Hi, S P S. Hopefully someone who is more knowledgeable about this will answer, because I don't see how you can measure things that are covered by Sa 2.5, like discoloration, visible oil, and greyness with a profilometer. Nor can I see how you can reasonably expect a given surface profile from performing operations that comply with a blast cleaning specification that is unconcerned about surface profile, and which apparently permits the use of any blasting material of any size for any amount of time.

However, you can certainly specify both requirements, just as you can specify that you want to buy a car with 5 seats and of red color. The color red is neither included nor precluded by the car having 5 seats.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey



November 1, 2008

A. I hope this will clear your queries on Blasting and surface preparation..

BLAST CLEANING - PREPARATION GUIDES
grade - BS 7079 SS 05 59 00
description, when viewed with the naked eye

SA 2
thorough blast cleaning:Commercial finish 65% clean
The surface shall be free from visible oil, dirt and grease, from poorly adhering mill scale, rust, paint coatings and foreign matter. Any residual contamination should be firmly adhering.
 
SA 2.5
very thorough blast cleaning: Near white metal 85% clean
The surface shall be free from visible oil, dirt and grease, from poorly adhering mill scale, rust, paint coatings and foreign matter. The metal has a greyish colour. Any traces of contamination shall be visible only as slight stains in the form of spots or stripes.
 
SA 3
blast cleaning to pure metal: White metal 100% clean
The surface shall be free from visible oil, dirt and grease, from poorly adhering mill scale, rust, paint coatings and foreign matter. The blasted surface must have a uniform metallic colour.

BLASTING GRADES

Following is a table giving a clear indication of the comparative blasting grades applicable to national and international standards:

BLASTING GRADE COMMON STANDARDS COMPARISON
SSPC steel structures painting council
BS 7079 British standards
SS 05 59 00 Swedish standards
BS 4232
NACE, National Association of Corrosion Engineers


white metal (SP5) SA 3
1st quality
grade 1

near white metal (SP10) SA 2.5
2nd quality
grade 2

commercial finish (SP6) SA 2
3rd quality
grade 3

RUST GRADES
A Surface mostly covered with adherent mill scale, with little or no rust
B Mill scale has begun to flake, rust has started to form
C Mill scale has rusted away or can be scraped off easily and slight pitting has taken place
D Mill scale has rusted away and general pitting can be seen with naked eye
Sanjay Mungee
- Baroda, Gujarat, India



June 11, 2009

Q. Dear sir
We want photographs of standard blasting profiles like Sa 2, Sa 2.5, Sa, 3 etc.
Regards

KIRIT D. PARMAR - coatings - Vadodara, Gujarat, India

August 13, 2009

Q. I want sand blasting profile books for SA2 and 2 1/2 with complete pictures. Please let me know where can I find this.
Thanking you in advance.

Shivaraju Ramarao - contractor - Vizag, AP, India

October 21, 2012

A. Hi Kirit; hi Shivaraju.
HMG Paints Ltd. offers a free 24-page PDF with pictures of these surfaces at:
https://www.hmgpaint.com/PDF/knowledge-base/KNB0026.pdf

But I think you'll want to try to get a look at ISO-8501-1, which is a hardcover 74-page book, and the actual official reference.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey



August 26, 2009

Q. I want to know what the term "Sa" in blasting standards actually stands for.
My boss always asks me and I cannot answer. Help me please...

Ahmad Sanusi
Painting Executive - Johor, Malaysia

September 5, 2009

A. SA stands for Standard Abrasive ... Similarly ST means Standard Tooling

Rahul T.
- Mumbai, India
October 28, 2009

A. Sa Simply stands for Sand as that is the abrasive medium that they used to determine the blasting standards on the 4 Rust Grades for ISO 8501-1 [link by ed. to spec at TechStreet].

Remember Sand was the most widely used abrasive back in the days before the health risks of silicosis were identified.

Alternatively St stands for Steel sorry its nothing more technical, but that's it guys, and the reason I know is that I asked SIS years ago when I first started Inspection to settle an ongoing debate between myself and a colleague.

The relationship between the standards Sa3 and 2.5 is practically identical except that a 2.5 allows for staining or traces of contamination i.e. Very thorough blast cleaning. When viewed without magnification, the surface shall be free from visible oil, grease and dirt, and from mill scale, rust, paint coatings and foreign matter. Any remaining traces of contamination shall show only as slight stains in the form of spots or stripes.

And Sa3 does not have any visual contamination present it is a white metal finish.

For a more definitive view at amounts of contamination which are allowed visually to be included in a blast please take a look at the joint Nace SSPC blasting standards which are equivalents, however not identical to the ISO 8501-1 standards. These standards give a better representation of the actual amounts of contamination which should be present.

Nace 1, SP5, Sa 3 = 0%
Nace 2, SP10, Sa2.5 = 5% Staining
Nace 3, SP6, Sa2 = 33% Staining
Nace 4, SP10, Sa1 = 100% as long as its tightly adherent

Lee Wilson Nace Level 3 Coating Inspector, Nace CIP Instructor & Lecturer, Icorr Level 3 Painting Inspector
inspection services - United Kingdom
February 5, 2010

thumbs up signThanks a lot everyone. It was really helpful.

Priya Suryakant
- Bangalore,Karnataka, India



ISO 8501-1

June 4, 2010

Q. Dear Sir,

I want to know about the detail of SA 2.5 about blasting for steel equipment.

Regards,

Shanthi K
project engineer - Chennai,Tamil Nadu, India


June 4, 2010

A. Hi, Shanthi. The general meaning of Sa 2.5 is explained above.

My understanding is that the full details are covered by specification SS 55900, available from the Swedish Standards Institute at www.sis.se -- but that this standard was actually canceled in 2001 and is now superseded by ISO 8501-1 [link by ed. to spec at TechStreet].

Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey


June 9, 2010

A. The blasting standards as depicted in ISO8501-1 are visual standards for surface cleanliness

Once a substrate is abrasive blasted the blast achieved is then compared to the visual reference pictures which are contained within ISO8501-1 and a comparison made between the blasting standard achieved and the standard required.

When you speak of Ra you are speaking of surface profile, roughness or anchor pattern which is the peak to trough amplitude of the blast profile usually expressed and specified in microns and created during the blasting process this is usually measured with surface replica tape, surface comparators or surface profile needle gauges however surface profile is not an indication of the surface cleanliness do not get confused surface profile and surface cleanliness as depicted in ISO8501-1 are separate requirements.

I hope that this helps

Best Regards

Lee Wilson Nace Level 3 Coating Inspector, Nace CIP Instructor & Lecturer, Icorr Level 3 Painting Inspector
inspection services - United Kingdom



January 17, 2011

Q. I would like reference/guidance for the relation between cleanliness standard with steel structural condition/type. Example: SA-2.5 is applicable for a structure on what conditions? Or what grade is suitable with what condition of structure?

Yuhanas Yuhanas
structure engineer - Jakarta, Indonesia


May 11, 2011

A. Sa.2.5 is expected for existing structure, while Sa.2 is for new installation.

Joseph Okoye
- Ikoyi, Lagos, Nigeria



May 5, 2011

Q. Sir
Can we use silica sand in following Sa 2.5 & Sa 3? If not, which kind of sand do we use?

Rana Akbar
employee - Rahim Yar Khan, Pakistan



August 21, 2011

Q. Which term to follow regarding surface preparation of storage tanks, whether surface cleanliness or surface profile or both because both seems two different requirement of surface preparation for applying coating on metal surface.

A. Aziz
- Karachi, Pakistan


October 1, 2011

A. It seems there is a whole book to be written on the blasting standard requirements, the differences between the required grades and surface profiles.
In short, our company approach the problem as follows:
The client needs to decide (or be advised depending on the application) what type of coating will be applied to the steel, this will decide the required blasting grade as specified by the coatings manufacturer (the norm seems to be SA2.5).The coatings manufacturer will also specify the required DFT (Dry Film Thickness) of the required coating to be applied.The DFT requirement is what needs to be looked at when one decides the roughness of a surface profile in microns.

Hans vd Linde
- Alberton, Gauteng, South Africa



October 26, 2011

Q. Please advise me how to inspect sand blasting for steel structures like I beam, channel, plate.
1. What the pressure should I maintain to get the fine surface preparation.
2. What microns should be there after sand blasting.

Mohamed Jaseem
quality control - Saudi Arabia


October 28, 2011

Q. I have a similar question to the one asked on October 26. For us we are being asked to prepare metal surfaces by Sandblasting to a Sp-10 level finish. What does that entail and how do we inspect for this?

Carlos M [last name deleted for privacy by Editor]
manufacturing - Stockton, California


thumbs up sign Hi Carlos. Some people spend their entire careers helping people answer that question, so I can't pretend that it's easy. But if you have a copy of SP-10, please try your best to phrase your questions in terms of what information you feel is lacking in that specification. If you don't have a copy of SP-10 in your possession yet, well, you probably shouldn't proceed until you do :-)

Luck and Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey


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