It is about the ringscrew thread smoke channel of the boiler shell type gas tube in the boiler field.
锅壳式烟管锅炉烟管内置水管的环形螺纹烟道，它涉及锅炉领域。
2
The method of 5-ringscrew hoop, 1-pen hoop and non-shrinkage high-strength mortar poured into sleeve is used at the seismic joint of new-type prefabricated reinforced concrete beam-column.