Metal Preparation for Fluoropolymer and Baked Coatings

The design of the metal vessel should be such that it is suitable to receive lining. For safety considerations, vessels designed to be of closed construction must have at least one 20” man-way along with other nozzles for proper ventilation. Larger vessels should have at least two man-ways. AST Acme criteria for fluoropolymer and baked coating:

Seams

1. All seams must have a continuous weld including nozzles.

2. All seams shall be butt welded wherever possible and continuous welded.

3. Overlapped seams are not acceptable.

4. Where dissimilar seams occur, a fillet weld must be done and ground to a smooth transition.

Nozzles

 1. All nozzles shall be flanged and a minimum of 1” in diameter.

            a)     Small diameter nozzles which are 3” in length or greater may not be able to obtain minimum film build and leak-free                     status may not be met in that area.

           b)  nozzles with 45 or 90 degree elbows will also have issues stated above (a).

2. Threaded fittings such as couplings or threaded pipe will not be leak free and should be avoided if possible.

3. The use of any internal bolted connections must be avoided.

Welding

1. All welding shall be continuous. Skip or spot welds are not acceptable.

2. Welds must be ground smooth and flush and be free of porosity, splatter and sharp

     edges. Undercutting must be avoided.

3. Sharp edges and fillet welds shall be ground smooth to a minimum radius of a (1/8" (1/4"

    is preferred). This includes nozzles as well.

4. All weld spatter must be removed from the tack surface or ground flush.

Structural Supports

Supports should be installed on the outside of the tank whenever possible. If internal supports cannot be avoided, simple shapes such as round bars or pipe should be used for ease of applying the linings.

Recommendations:

1. AST Acme will send all Quality Assurance documents to customer and/or jobsite.

2. AST Acme encourages a customer representative to witness final spark-test and inspection.