HG/T 21529-2014
板式平焊法兰手孔
Plate flange handholes
2014-07-09
HG/T 21530-2014
带颈平焊法兰手孔
Slip on flange handholes
2014-07-09
HG/T 21516-2014
回转盖板式平焊法兰人孔
Plate flange manholes with hinged cover
2014-07-09
HG/T 21522-2014
水平吊盖板式平焊法兰人孔
Plate flange manholes with davit to horizontal cover
2014-07-09
HG/T 21519-2014
垂直吊盖板式平焊法兰人孔
Plate flange manholes with davit to verticla cover
2014-07-09