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Paint selection for carbon steel surface which is not blasted

Paint selection for carbon steel surface which is not blasted

(OP)
Hi all.

I am working in a company that designs carbon steel products out of plate, bar and pipe material. We do not have manufacturing facility and neither we nor our fabricators have painting facility. As we obviously need to protect our products, and do not have where to paint them, we are using paint that does not require any special surface prep and paint in house. We leave pipe coated with anti-corrosive protection layer (blue or black, depending on the mill) and grind/sand off any rust accumulated on the rest of the material and weld areas. Basically prep the surface to SSPC-SP2/3 and apply the paint. For years we have been using Benjamin Moore Z24 Alkyd-Enamel (semi-gloss) brushed on. This is our standard paint procedure for service up to 350 °F. If we have a design for higher temps, we get these out to painting vendors for proper paint.

IS there anyone that can recommend any other paint that can be used for the above mentioned temperature and surface prep? Current paint is easy to use, but the finished product is something that i am not satisfied with. The surface becomes dirty rather easily and it just doesn't look too nice. I understand that without proper surface prep it is almost impossible to achieve good finish. I am just hoping that someone here can recommend something that is an improvement to the existing paint selection. I would like to stay away from epoxy coatings as those harden rather easily, want to keep it as simple as it is (we do not have a dedicated painter. whoever is free paints the equipment and sometimes, they need to be pulled away from the painting job to do something else ). We also do not like to have glossy finish. Semi-gloss, eggshell would work (not sure if this matters though).

Thanks in advance

RE: Paint selection for carbon steel surface which is not blasted

Surface tolerant epoxy. Takes a little more care- you need to mix the two parts properly- but it sticks like glue, because it's basically glue itself. Very durable, and as long as your surface is adherent (nothing loose and flaking) and free of grease/oil, it will adhere well. Gives a good gloss and cleans easily, but does not retain gloss very well. No good above about 250 F, but neither is any organic-base paint in my opinion. Your alkyd enamel certainly wasn't any good above 250 F either.

RE: Paint selection for carbon steel surface which is not blasted

Agree with MM. Also, one reason it coating appears to get dirty quickly is that you are applying by brushing. Spray applied coatings do not have the brush striations and do not collect dirt/debris as easily.

RE: Paint selection for carbon steel surface which is not blasted

I took a look at the datasheet for this paint and it specifically states two coats should be applied. It should be applied between 40-90degF. The first coat should be allowed to dry for 16 hours at 70degF and 50%RH before applying the second coat. And as moltenmetal noted, this paint is not suitable for exposure to 350degF temps.

Are you following all of these guidelines?

RE: Paint selection for carbon steel surface which is not blasted

If the 350 F is important, you have really only three options: inorganic paint (barbeque or engine enamel), inorganic zinc (which is just a primer, not a finish coat), or a polysiloxane. The first is easy, the 2nd REQUIRES a blast profile and enough moisture in the air to cure, and the 3rd is very, very expensive.

RE: Paint selection for carbon steel surface which is not blasted

(OP)
moltenmetal - Epoxy paint will not work as the temp rating is not sufficient. Also, our shops do not have painters on staff and do not want to waste their time on painting, when they could be welding. So they would simply decline to paint with 2 part system

Ron - the finish is not that bad. Brush strokes are not that visible. The finish is just the way it is. It is like a magnet for dirt.

tbulena - i believe we are loosely following that. In case the air is dry or it is colder, we would still paint. We wouldn't postpone painting just because it is, let's say, 38 degrees.

moltenmetal - 350 °F is important. I was actually hoping I would be able to increase the temp rating. inorganic zinc is out as it needs blasting, doubt that polysiloxane will be an option as it is expensive (how expensive?). With inorganic enamel what are my options? They can be found in any store in spray can, but do they come in cans/buckets? can they be brushed on? Would you be able to provide any paint recommendation from one of the brand name manufacturers (PPG, BM, SW, Jotun, International...)?

As i wrote above, our units are in process industries so we get no points for the looks. Need to protect it and that's it. For me it is important to have the following:
- at least 350 °F rating (hopefully more)
- able to be brushed on
- one part paint
- not glossier than semi-gloss finish

RE: Paint selection for carbon steel surface which is not blasted

(OP)
*** UPDATE

I found a not in our system that one of our engineers had a discussion with Benjamin Moore rep, which told us at the time, that the paint is good up to 350 °F....

RE: Paint selection for carbon steel surface which is not blasted

It makes a difference whether you speak with a Tech Rep or a Sales Rep. The Sales Rep will tell you anything. The Tech Rep is usually slightly more reliable. In either case, I think you were given some bad info. It takes a relatively special formulation to handle 350 degrees....most alkyd enamels won't do that.

As for epoxies....there are numerous formulations that will handle high temperatures. Check with an industrial supplier such as Intertherm, Tnemec or Carboline. Benjamin Moore's greatest market is consumers and residential contractors.

RE: Paint selection for carbon steel surface which is not blasted

Alkyds are not going to hang around at 350 F, regardless what your rep says. All that will be left after a year at 350 F is an oxidized mess and the pigment- of course you won't notice that, because it'll be under insulation.

You really want barbeque paint- a high temperature non-alkyd enamel. Easy to apply, 1 part, and only modestly less protective than an alkyd enamel.

RE: Paint selection for carbon steel surface which is not blasted

(OP)
Thank you guys. Your replies are helpful.

Thank you moltenmetal. As i do not know much about the paint i will need to ask a stupid question. Would you be able to give me an example of the paint you're talking about? I went to manufacturer's websites and they do not list anything under enamel. Inorganic or non-alkyd enamel does not help me as well.

As far as BBQ paint, there is rustoleum paint but that comes only in spray cans...

Thank you

RE: Paint selection for carbon steel surface which is not blasted

(OP)
unfortunately, it seems that we do not have those in cans here in the US.

Is there anything from International, Carboline or similar manufacturer ?

RE: Paint selection for carbon steel surface which is not blasted

HP steam ,
You could use brush on exhaust manifold paint, the only problem is the stuff comes in a limit range of colors. red, grey , black. and silver.
These paints are good from 1200 to 2000 degrees F depending on color.
B.E.

You are judged not by what you know, but by what you can do.

RE: Paint selection for carbon steel surface which is not blasted

That TYPE of paint, as berkshire has pointed out, is definitely available in the US. Sorry, but at a certain point you have to do some of the work yourself. We've pointed you in the right direction and cleared up some of your misperceptions- the rest is up to you.

RE: Paint selection for carbon steel surface which is not blasted

(OP)
Fair enough.

Thank you for all of your help. This did help me enough to continue on my own.


Thank you

RE: Paint selection for carbon steel surface which is not blasted

I've used a product called MCU-100 Aluminum from Gulf Coast Paint Mfg., Inc. It's made for steel where you have minimal prep done. I've done it on tanks as well. High heat resistance up to 400 degrees F. Best product out there for minimal prep on steel.

RE: Paint selection for carbon steel surface which is not blasted

I did not see what color you are painting your products.
I'd kind of expect a light color would show dirt and liquid contamination more quickly, and I also wonder if the semi-gloss is contributing to the short lived finish.

I wonder if a catalyst additive would make the present paint finish more durable and dirt resistant.
http://www.tractorsupply.com/tsc/product/majic-cat...

Kind of poisonous at least when sprayed, and speeds up dry time, which perhaps you do not want.

RE: Paint selection for carbon steel surface which is not blasted

Tmoose, not sure I believe that..

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