... ,SMS,BS,AS,BPE etc welding sight glass (joining sight glass ,Welding and Joining Sight Glass) welding sight glass (joining sight glass ,Welding and Joining Sight Glass) Specification :Material:AISI304 AISI316LSpecification:DN25 ... roughness , material quality and Industry standards and has these characteristics, with a simple structure, handsome in appearance, disassembly fast, flexible operation ...