DIN EN ISO 28721-4:2013 釉瓷和搪瓷.加工廠用玻璃襯里裝置.第4部分:涂瓷釉凸緣鋼和凸緣鋼配件用質量要求(ISO 28721-4-2010).德文版本EN ISO 28721-4-2012
Vitreous and porcelain enamels - Glass-lined apparatus for process plants - Part 4: Quality requirements for glass-lined flanged steel pipes and flanged steel fittings (ISO 28721-4:2010); German version EN ISO 28721-4:2012