ASME B16.3 pdf download Malleable Iron Threaded Fittings Classes 150 and 300 (a) Meta! Thickness Tolerances. Metal thickness at nopoint in the castings shall be less than 90% of the valuegiven in the tables. (b) Center-fo-End Tolerances. Permitted tolerances onthe center-to-end dimensions of the fittings are shownin Tables 2 and I-2. Tolerances for end-to-end dimensionsand lengths of couplings and reducers...