2a 2nd end thread class 12 1st end thread quantity per inch 2nd end bulkhead thd 1.062-12 in., cl 2a, un paint surface treated un 1st end thread series
3a 1st end bulkhead thread class material corrosion resistance steel (15-5ph) cadmium plated; first end has bulkhead threads cadmium surface treated unjf all ends thread series
Used on starlifter c-141. 3a 2nd end thread class 18 2nd end thread quantity per inch 1st end bulkhead thd 0.500-20 in, cl 3a, unf unf 1st end thread series