Technical Bulletin

113
January, 1992
Supersedes all previous publications

1. SCOPE OF WORK

   It is the intention of this specification to describe and recommend the metal surface preparation required of the fabricator in order that tanks, weldments and other fabricated work shall be suitably finished for the satisfactory application of the HERESITE lining.

2. WELDS AND JOINTS
   1. All vessels shall be of butt welded construction. All internal seams shall be welded. All welds on surfaces to be coated shall be continuous and shall be free of voids, gaps, craters, pits, high spots, sharp edges and undercutting.
   2. High spots, irregularities, sharp edges and metal peel shall be removed by grinding.
   3. Nozzles shall be attached by insertion flush with the interior surface and with full interior weld. Edges shall be rounded to a 1/8" radius minimum.
   4. Flanges on nozzles shall be of the slip-on type with a lull fillet weld at the junction of flange face and the edge of the nipple and ground smooth to a 1/8" radius minimum. Weld neck flanges shall not be used.
   5. Threaded connections are not satisfactory.
   6. Weld splatter shall be removed.
   7. Test gaskets shall be of a type not requiring the use of grease as a seal.
   8. All machined edges sha11 be rounded to a radius oi 1/8".
   9. Oil or grease as a rust preventative and cutting oils in machining operatians shall be avoided.
   10. For storage vessels, it is recommended that they be fabricated with flanged heads as inner corner welds are difficult to prepare and coat.
3. SPECIAL REQUIREMENTS FOR LIN1NGS TESTED FOR HOLIDAY FREE
   1. Where specifications call for holiday free coating or lining, all internal welds shall be ground smooth (not necessarily flush) and be free of ail defects.
   2. We recocommend the use of a Tinker & Rasor Model M-l (67-1/2 volts) wet sponge test or equal, not a high voltage spark test as it can damage the coating.
   3. All other requirements sha11 apply as outlined above.
   4. We shall be glad to advise if holiday test is required.
4. LIGHT GAUGE SHEET METAL, DUCT WORK, ETC.
   1. All seams shall be butted and shall be welded with full penetrating welds, free of voids, gaps, craters, pits, high spots, sharp edges and undercutting.
   2. Backing strips shall not be used.
   3. Connections shall be of the flanged type. Slip joints shall not be used.