船用放泄螺塞焊接座配套放水塞不锈钢放泄螺塞A型无肩船底放泄螺塞常用代号AO30-30NAO30-30HAW30-30NAW30-30HAW42-30AW42-35AW42-55AW52-35AW52-45AW52-55B型有肩船底放泄螺塞常用代号BO30-30NBO30-30HBW30-30NBW30-30HBW42-30BW42-35BW42-55BW52-35BW52-45BW52-55)