Sealer application on TSA

[Massey]

My name's Massimo,
I work for a sandblasting and painting company as Q.C. manager and job supervisor .

I'm new on this forum so I would like to say Hello to everybody!


I have seen that there are a lot of really experienced people on this forum!
So, I would like to take advantage of them and post some questions

- I got a Thermal Spray Application specification ( the job regards pressure vessels all in carbon steel) with indicated " The water Test" after metallizing operation ( 250 micron DFT -with aluminium 99,5%). I 've never heard about this test. In fact the test ask for: " ..wet the surface after metallization with potable water, than wait for 48 hours to see if rust, blistering or some other defects appears. If the test is passed You can proceed with the sealer application ( silicone aluminium)".

In my previous TSA jobs ( always on pressure vessels) I have ever had the mandatory of: " ..apply the sealer as soon as possible".

Any suggestions please?!

Thank You !!
massimo

[Vijay Deshpande]

Dear All, We also carry out Lot of TSA work.how ever this test is new to me as it is not mandatory for Off Shore work also.
There are few doubts regarding remedial action if this test fails.
as it will be difficult to remove part of the coating and repray again.
thanks
Vijay Deshpande

[Gordon]

Hi Massimo

to the Surface Engineering Forum.

I have not come across this test before. Do you know if this test is applied only to test pieces or the job as a whole?

[Massey]

Gordon Wrote:Hi Massimo

to the Surface Engineering Forum.

I have not come across this test before. Do you know if this test is applied only to test pieces or the job as a whole?

Hi Gordon,
thanks for Your welcome!

In fact the spec ask for a test performed on the whole treated surface ( more or less 130 square meter!).


Anyway , I will have a pre job meeting, in the near future, with the engineering company delegated, and I am determined to ask for some review of this point.

Massimo

[Gordon]

Hi Massimo

Two comments:

Fresh aluminium coatings can sometimes suffer rust coloured spotting/staining. This can occur soon after processing usually within days. I assume this is an initial corrosion effect which quickly stifles itself as the coating self-seals. It can be a bit disconcerting and doesn't enhance aesthetic qualities, but it appears not to effect the primary anti-corrosion function and life of the coating. I think this test would increase the likelihood of this effect.

I would feel nervous about sealing on top of a potentially moisture laden coating, certainly without efforts to force dry first.

[Massey]

Gordon Wrote:Hi Massimo

Two comments:

Fresh aluminium coatings can sometimes suffer rust coloured spotting/staining. This can occur soon after processing usually within days. I assume this is an initial corrosion effect which quickly stifles itself as the coating self-seals. It can be a bit disconcerting and doesn't enhance aesthetic qualities, but it appears not to effect the primary anti-corrosion function and life of the coating. I think this test would increase the likelihood of this effect.

I would feel nervous about sealing on top of a potentially moisture laden coating, certainly without efforts to force dry first.

Hi Gordon,
I totally agree with your analysis. Considering that I am going to treat about 15/20 square meter for once of the entire vessel surface, go on with this test could let me face with some troubles!

Anyway I will let You, and all the forum people,know, what the Engineering company will tell me.

Thank you very much!

massimo

[Alexangel1226]

Massimo,

Just out of curiosity, is the pressure vessel actual application is working under sea or submerged under water or something?

[Massey]

Alexangel1226 Wrote:Massimo,

Just out of curiosity, is the pressure vessel actual application is working under sea or submerged under water or something?

Hi Alexangel, sorry for the late reply.

No under water or similar envinronment. The vessel will be insulated and than, placed in a industrial compartment.

regards,
Massimo

[LouisRichter]

Hi Folks,

a few questions slightly related to this thread:

1) hat is your experience with Sealer Coats on TSA? As far as I understand the process, a Sealer Coat is not required and even hinders the electrochemical protection provided by TSA. As long as TSA is applied correctly and with DFT > 250 µm, there shouldn't be any problems.

2) Which Product would you use as Sealer Coat? Is a simple epoxy material sufficient or is a Silicon-Aluminum colour better? Does it have any influence whether the coat contains Al particles or not?

Thanks for your feedback!

Regards, Louis