Pull of Adhession Test ASTM D4541 1

[Syahar1975]

Good evening,

In ASTM D4541 is there any clause about how many point the pull off adhesion test must be done ?

If there 4 tanks with the same painting system do we need to make 1 sample test for each tank ?

Or 1 sample test is sufficient since the system is the same.

Appreciate your comments.

 

[Ron]

ASTM D4541 does not specify the number of tests to be run. That is left to the parties involved to decide.

I rarely do any testing of only a single point. In my opinion, you should be doing a series of three replicate tests for every few hundred square feet of surface area. Yes, that's a lot of testing; however, it gives you a good representation of the quality of the coating application.

I would also not limit the testing on only the pull-off testing. I would check dry film thickness and peel test using an "X" knife test.

If you are not familiar with D4541 and the equipment to be used, I would suggest that you buy the standard and get familiar with the equipment before you do the field testing. Preparation of the test dollies and attachment to the surface are very important. You want to make sure that the bond between the test dollie and the surface is considerably stronger than the expected bond strength of the coating to the substrate.

 

[Figueredo]

The same paint system does not guarantee the same conditions for the application because the conditions of environment, suppliers and contractors can change, you should be doing a series of three replicate tests for every few hundred square feet of surface area FOR EACH TANK

RON have a good explanation.

Later you need repair the small area.

REGARDS.

 

[Syahar1975]

Ron , Figueredo, Thanks for the comments.

Unfortunately there is no statement in the approved procedure about how many points to be checked.

The painting subcontractor propose since we have only 4 paint system for 20 tanks and most of the tanks will have the same paint system each other so the adhesion test would be applied for these 4 system only.

They will make 4 test plate (300 mm x 300 mm) representing 4 system. Each plate will have 3 location for adhesion test.

It is very difficult for me to argue since this proposal had been approved by someone who does not know or very seldom involved in painting.

I agree with your comments. How come these 4 test plates can give us assurance for 20 tanks. Moreover these tanks are located in different area and painting may be done in different climate (winter or summer). Even we are using the same painting contractor.

We are to far behind schedule so nobody concern about this issue. Only tanks completion is our focus now.

This is very good lesson for me for future project. Need to be addressed and agreed during reviewing the painting procedure.

Syah

 

[Ron]

Do not use test plates to assess the coating application quality. They will not represent the placement of the coating onto the tanks. Test the coating on the tanks.

The test plates will likely be specially prepared, and they will likely be sprayed in a horizontal position while the majority of the paint coating will be placed in a vertical position.

 

[CoCoE]

Mr. Syahar1975,

If you are looking for the qualification of your paint system performance, Yes! then these 4 test plates with 3 tests will be adequate. But if your intention is to do the quality control of your application, as explained above you must have the test plates painted at the same time of production coating application (ie, same batch and environmental conditions). I don't know how big your tanks are, but you must keep a test plate either in a few 100 meter squares or like two test plates for one paint system for one day. I hope that will do.

 

[Ron]

krishn4...I respectfully disagree that the plates will represent the paint system performance. The purpose of testing a coating as applied is not to assess its performance but to assess its application process. There are two assumptions that have to be made from the application process to reach an assessment of the system's performance. First one has to assume that the coating is correct for the application. Secondly, one has to assume that if the coating is installed in accordance with the manufacturer's application instructions and to the proper thickness that it will perform its intended purpose as previously tested by the manufacturer for long term efficacy.

 

[Syahar1975]

Good morning Gents.

Appreciate your comments,

Khrisna4, Actually this plate is production test plate. We paint this plate together with underside roof plate of the tanks. But yes they paint this production test plate not in overhead like underneath roof nor vertical like shell. But they put the production test plate on bottom which is the easiest way.

Ron, I have requested like you said. Pull off on each part (roof underside, shell plate and floor plate) of the tanks because different difficulties or production test plate for each position on each tank.

But again since the procedure had approved and project schedule issue, I have to agree with the painting subcontractor proposal which is the most easiest way for them.

We check the thickness and holiday test on each part of the tanks.

Syah

 

[CoCoE]

Ron, thank you for your feed back.
I meant the performance in terms of adhesion, and not in service related means. Also test plate will help you if there is any problem with a particular batch. And frankly speaking, there is no meaning of doing adhesion test on the tank itself, and I am against that since it will be creating the outset of real corrosion to start on. If there is proper atomization, speed, pressure and deposit, there is no major concern of varying performance of the coating even though you apply it by bicycling.

My opinion is purely personal.

All the best!