HG/T 21534-2014
旋柄快开手孔
Quick open handholes with rotating handle
2014-07-09
HG/T 21604-2014
旋柄快开衬不锈钢手孔(附条文说明)
Lining stainless steel swing-type quick opening manholes
2014-07-09
HG/T 21525-2014
常压旋柄快开人孔
Quick open manholes for atmospheric use
2014-07-09