TSA COATING
11-30-2008, 03:19 PM,
#1
TSA COATING
Dear All,
Whats maximum achivable value for adhession test for TSA coatings.
Is there any data available. The anchor profile is 85 to 90 microns using copper slag. The dust level C2 R1
We are getting values between 9 to 15 MPA with mechanical Dolly puller
Thanks and Regards
Vijay Deshpande
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12-01-2008, 10:55 AM,
#2
RE: TSA COATING
From the values you mention, I assume you are using Arc spray but please confirm.

Are you testing with a dolly on the job (e.g. bonded to the flat sheet for example) or have you prepared specific test dollies to use in a tester?

What is the coating thickness?
Stuart Milton
Metallisation Ltd
https://www.metallisation.com
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12-09-2008, 02:47 PM,
#3
RE: TSA COATING
(12-01-2008, 10:55 AM)Stuart Milton Wrote: From the values you mention, I assume you are using Arc spray but please confirm.

Are you testing with a dolly on the job (e.g. bonded to the flat sheet for example) or have you prepared specific test dollies to use in a tester?

What is the coating thickness?

We are using Twin wire arc spray system using 1.6 mm wire. The test is carried out on job reference samples ( 400 mm X 400 mm 8 mm thick)and coating thickness is 150 to 200 microns.
Thanks and regards
Vijay Deshpande
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12-10-2008, 01:23 AM,
#4
RE: TSA COATING
Based on Norsok standard M-501 Rev. 4 December 1999 - Surface preparation and protective coating - table 11.1 Inspection and testing, please see notes : 1. For system no 2 ( Thermally sprayed aluminium or alloys of aluminium coating system ), adhesion during qualification shall be minimum 9.0MPa. Adhesion measured during production shall be minimum 7.0MPa for any single measurement.
Others information :
Surface preparation: Cleanliness : ISO 8501 Sa 2.1/2 - Roughness : ISO 8503 Grade medium G ( 50-85 Mic.mm, Ry5).
Thickness : Minimum 200 Mic mm.
Hope some helps to all.
Thanks & Regards,
Iwan Sedaryawan - Website : https://www.ciptaagung.com
Happy0193
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12-10-2008, 03:15 PM,
#5
RE: TSA COATING
Hi Vijay

I remember overseeing some operator approval/qualification testing, similar to what iwan-sedaryawan described above.

The basic requirements were:
Surface preparation roughness >85 - 130 Ry5 and >6 Ra
Coating thickness 225 - 400 micrometres
Adhesion test (ASTM C-633) >9 MPa
Adhesion test (ASTM D-4541) >7 MPa

Out of 5 operators, which all passed qualification:

The worst:
13 - 16 MPa (ASTM C-633) All coating failure
14 - 16 MPa (ASTM D-4541 using HATE tester) All coating failure
Even though this operator was well within the requirements for qualification, I thought he required more training/experience as his coating results were significantly poorer than the other operators.

The best:
25 - 27 MPa (ASTM C-633) Mix of adhesive and coating failure
13 - 23 MPa (ASTM D-4541 using HATE tester) All adhesive failure

With tests where adhesive failure occurred, actual maximum coating adhesion/bond strength can not be determined.

Grit blast preparation was using chilled iron grit (G12).

So to answer your question
Quote:Whats maximum achivable value for adhession test for TSA coatings.
I would say >25 MPa with good operators, good equipment/process/preparation and good testing equipment/adhesives.

Quote:We are getting values between 9 to 15 MPA with mechanical Dolly puller
If you are getting adhesive failures rather than coating failures, I would not be to concerned. If they are coating failures, then I think you could do better.
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12-13-2008, 03:44 PM,
#6
RE: TSA COATING
Thank you all for ur replies
Vijay Deshpande
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12-19-2008, 06:35 PM,
#7
RE: TSA COATING
Dear All,
can any one sugeest me to improve bond strength of TSA coating
Regards
Vijay Deshpande
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12-20-2008, 12:52 AM,
#8
RE: TSA COATING
As per gordon says : adhesive failures rather than coating failures, pls check while you do the pull off test with dolly, it is in substate or between glue & dolly ? 70% successfully with maximum bonding strenth is depend on the preparation itself, check your grit blasting, presure etc, use roughness tester, surface comparator to achieve Sa 3 (white metal) surface cleanliness, I am sure you will get better bonding strength than before, based on our experience we can achieve more than 20MPa, around 25 MPa.
Having fun with TSA coating
Thanks & Regards,
Iwan Sedaryawan - Website : https://www.ciptaagung.com
Happy0193
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12-20-2008, 03:54 PM,
#9
RE: TSA COATING
(12-20-2008, 12:52 AM)iwan-sedaryawan Wrote: As per gordon says : adhesive failures rather than coating failures, pls check while you do the pull off test with dolly, it is in substate or between glue & dolly ? 70% successfully with maximum bonding strenth is depend on the preparation itself, check your grit blasting, presure etc, use roughness tester, surface comparator to achieve Sa 3 (white metal) surface cleanliness, I am sure you will get better bonding strength than before, based on our experience we can achieve more than 20MPa, around 25 MPa.
Having fun with TSA coating

Most of the times its mix of glue and adhession failure. How ever we have not got a single cohesion failure
Regards
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05-28-2009, 03:33 AM,
#10
RE: TSA COATING
What adhesives are you guys using to achieve 27MPA?
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05-28-2009, 02:32 PM,
#11
RE: TSA COATING
(05-28-2009, 03:33 AM)wrjordan Wrote: What adhesives are you guys using to achieve 27MPA?

Brand is Araldite, if you need to know the type we will you know by tomorrow morning...
Thanks & Regards,
Iwan Sedaryawan - Website : https://www.ciptaagung.com
Happy0193
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10-11-2009, 03:03 PM, (This post was last modified: 10-11-2009, 03:06 PM by markdavidson.)
#12
Adhesion of flame spray TSA repaired with arc spray


I have some carbon steel equipment which has been flame spray TSA coated and has arrived at the fabrication yard with some damage. It will need repair but the yard TSA contractor only has arc spray equipment. The TSA contractor says it is unwise to repair using arc spray but is not clear why, some within our yard construction team believe it may be due to adhesion loss of the original flame spray TSA where it is overlapped by the repair arc spray. I am interested to hear of actual experience, does the overlapped flame spray lose adhesion?

Regards
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10-11-2009, 10:09 PM,
#13
RE: TSA COATING
Many regional Anticorrosion specifications are based on a more than decade old but still valid US guide. This specification provides information about repairing damaged coatings but recommends that the process used be the same as the original. It does however state that arc sprayed coatings can be repaired by Flame spray but not vice versa. I believe the primary reason is the much higher bond strength of arc sprayed Aluminium and the fact that this would compromise the existing/adjacent flame spray deposit - Gordon?

There is a 'fast paint only' repair option which you could consider if flame spray process was definitely unavailable. Obviously this would be second best.

Send me a PM with your email and I'll send you the document.

Cheers
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10-12-2009, 09:07 AM,
#14
RE: TSA COATING
The 100% foolproof method is to remove the coating completely and start again. Back now to the real world......

The repair processes that GlenB mentions will suggest blasting back to a good, sound base and feathering the edges of the coating. Problems may occur if the flame sprayed coating was poorly applied in the first place and has a low bond strength - as you blast you can keep taking off more and more coating. Another consideration is if the coating has been sealed. Ideally you need to get the coating blasted back to an unsealed level but obviously at the feather edge, this will not be possible so you may have bond issues at the edges (regardless of repairing with flame or arc).

As GlenB mentioned, the probable concern for arc over flame repair is that the higher bond strength and stresses in an arc aluminium coating may try to pull the flame sprayed aluminium coating off. As long as the bond of the flame coating is sound (around 7MPa is a reasonable level) and care is taken to build up the arc coating slowly with multiple thin passes (creating a less stressed coating), then it should be OK. Lots of ifs, buts and maybes though.

Good luck - please let the forum know how you get on.
Stuart Milton
Metallisation Ltd
https://www.metallisation.com
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10-12-2009, 02:41 PM,
#15
RE: TSA COATING
Hi Markdavidson

Sign0016 to the Surface Engineering Forum.

Can only echo GlenB and Stuart Milton comments.

Can you give us an idea to the extent of the damage to the coating?
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10-13-2009, 08:37 AM,
#16
RE: TSA COATING
Glenn/Stuart/Gordon,

Thanks for your responses. I have asked our coating inspectors at the yard to coordinate a trial by the TSA contractor, 1 set each of 3 dollies fixed to the (1) intact flame spray, (2) the arc overlap of the flame spray and (3) new arc spray to determine adhesion and provide some basis for future assessments and quieten the nay-sayers. The extent of defective coating is probably less than 5% of total area, distributed over the entire structure. Transportation damage is about 1-2%.

I'm hopeful that the yard superintendant will allow the trial to go ahead. In the meantime I've been advised that due to the construction schedule these items will be completely stripped and recoated by arc spray so they can be welded onto the particular topsides deck.




(10-12-2009, 02:41 PM)Gordon Wrote: Hi Markdavidson

:sign0016: to the Surface Engineering Forum.

Can only echo GlenB and Stuart Milton comments.

Can you give us an idea to the extent of the damage to the coating?
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10-13-2009, 03:02 PM,
#17
RE: TSA COATING
Hi Mark

Sounds like a worthwhile test to me, particularly if you are likely to face the prospect of needing patch repairs in future.
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