There shall be a physical means to maintain this minimum liquid level, such as a weir or pipe end elevation.3.3.17All gaskets used on flanges of manways or piping to the inner tank shall be selected according to the “Field-Erected, Flat Bottom Tanks” section in SPEC-ENG-MQ057.Options for Enhancements3.3.18Inner Tank Stiffener Ring “Mouse hole” DetailWelds at stiffener ring mouse holes shall be 100% continuously welded through the mouse hole, without the 50 mm offset shown in API STD 620 Figure Q-1.