DIN EN ISO 28721-4-2013 釉瓷和搪瓷.加工厂用玻璃衬里装置.第4部分:涂瓷釉凸缘钢和凸缘钢配件用质量要求(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