"Std. 12-C covers general specifications@ including chemical and physical properties by reference to ASTM standards; together with permissible working stresses in welded tank joints and in reinforcement of openings@ with complete details on erection@ inspection@ testing@ repairs during construction@ on welding@ including definitions of joints@ and qualification procedure for welding operators and for welding procedures. While Std. 12-A on Riveted Tanks provides scope rate details drawings@ these are not necessary in the case of Std. 12-C on Welded Tanks@ although the printed specification contains explanatory sketches@ showing types of joints@ etc. Std. 12-C permits the manufacture of tanks of any size@ consistent with current practice@ and in that respect differs from Std. 12-A (Riveted Tanks)@ which definitely fixes. the. .diameters and heights of riveted tanks. Tanks under Std. 12-C may have any width of shell plates@ with minimum of 72""@ and in any desired combination of. wide and narrow courses. Plate-thickness limits are included. Std. 12-C gives complete specifications@ including sketches@ on appurtenances. such as shell and roof manholes and nozzles@ draw-off elbows and sumps@ and platforms@ stairways and walkways for all welded Oil storage tnks. The API monogram is permitted by licensed manufacturers under Std. 12-C@ Fourth Edition@ by means of a standard name plate@ the same as stipulated in Std. 12-A@ to be placed on the reinforcing plate@ or shell plate immediately above the manhole."