Internal Epoxy Painting on smaller vessels

[k2012]

We have requirement of internal epoxy painting of carbon steel volume tanks. The smallest size is dia 350 mm and height 700 mm. Internal coating before hydro test is not permitted by client, hence all fabrication must be complete before hydro test and then internal painting. So only access for surface preparation, painting and further inspection is through 6" hand hole located at the middle on the shell. Al though our painting subcontractor confirms that all the equipment can go inside the 6" hand hole, any suggestions on the technique, advanced equipment to control and monitor the process will help.

 

[GenB]

Find a company that does epoxy by filling and emptying the vessels. I think they spin and then cook them to finish the process.

 

[k2012]

Thank you GenB for your feedback. I am approaching some local companies other than my painting sub-contractors that do epoxy painting and everybody is confirming that it can be done although difficult. However getting details on how it can be done is difficult from these sub-contractors. I am looking for the technical details on how it can be done from experiences if any forum members already have.

 

[LittleInch]

The issue as I see it is how to do a final grit blast to get rid of the inevitable rust bloom and any water left trapped.

Flexible blast nozzles and flexible spray heads I have seen used in pipe connections down to 4", but doing any QA on them is virtually impossible ( e.g. dft or wft) and they tend to have runs and sags if you inspect it with a boroscope or similar.

don't understand the issue with doing this before hydrotest? Seems rather odd to me bearing in mind that it should be the long term integrity of the coating which matters.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[k2012]

Hi Littleinch,
If the painting is permitted before hydro test (UG 99 k1, k2) allows this subject to client approval), we can have tank partially fabricated and painted inside. Then it becomes easy to weld the top dish end and paint the remaining unpainted area i.e. top seam circumference.
However if this is not allowed, then complete internal painting becomes difficult but not impossible. I am looking for advance techniques / methods such as filling, emptying, spinning and hot drying as mentioned by GenB or flexible blast nozzles and flexible spray heads as mentioned by Littleinch.
Some of the references I got are as below but looking for more from the experience forum members might have.

https://www.youtube.com/watch?v=3WSKHTUrvyw

https://www.youtube.com/watch?v=rikQTU0xYUI

 

[r6155]

How can you control the coating thickness?

Regards
r6155