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Designed to AASHTO H20 requirements, each manway is constructed of A36 steel plate from 10 ga. to 1/4″ thick with lids of 3/8” reinforced checkered steel plate.  Round GLMs are available in diameters from 12″ to 48”. Designed around a 1-5 door configuration, rectangular GLMs are available in widths from 48″ to 72″ and lengths from 48″ to 150″ in 6″ increments. Download brochure.