Internally multi-lead rifled steel tubes shall be applied on water wall of power plant boilers, as main component for heat exchange, the rotary movement of water caused by internal spiral ribs can eliminate steam film on tube inner surface and thus achieve nucleate boiling. There are two types of internally ribbed tubes: Multi-lead rifled tube and Optimized multi-lead rifled tube.
Multi-lead rifled tubes are grouped into two types, designated Type A and Type B, with 30 degree helix angle, these unique products can improve thermal efficiency by 30%, in comparison to bare tubes.
Optimized multi-lead rifled tube is a newly-developed ribbed tube, its helix angle is up to 40 degree and more, thus can further improve thermal efficiency by 20% in comparison with ordinary multi-lead rifled tubes, which certainly have better heat transmission performance;
Detail see heat-transfer characteristics below, including bare tubes, multi-lead rifled tubes and optimized multi-lead rifled tubes:
Below is a comparison table of Changbao T12 OMLR type rifled tubes and Benteler product
产地 Manufacture | 外径 OD mm | 壁厚 WT mm | 螺纹头数Number of ribs | 螺纹高度Specified rib height mm | 螺纹顶宽 Rib width at top mm | 螺旋升角° Lead angle | 螺纹侧边角° Rib side angle |
Benteler 35*6.5 | 34.92 | 20.55 | 6 | 1.26 | 5.81 | 42° | 56° |
常宝CB 31.8*5.5 | 31.75 | 20.15 | 6 | 1.25 | 5.91 | 42° | 65° |
常宝CB 34.9*6.1 | 34.96 | 21.40 | 6 | 1.31 | 6.04 | 44° | 66° |
Main steel grades
20G、SA210C、SA210A1、15CrMoG、12Cr1MoVG、T2、T12、T23、T91
Standard (Part)
GB5310-2008、GB/T 20409-2006 Chinese National Standard Multi-rifled seamless steel tubes for high pressure boiler
ASME SA-210M-2015 Standard Specification For Seamless Medium-Carbon Steel Boiler And Superheater Tubes.
ASME SA-213M-2015 Specification For Seamless Ferritic And Austenitic Alloy-Steel Boiler, Superheater, And Heat-Exchanger Tubes.O.D.：Φ22mm~Φ82.6mm；WT.：4.0mm~16.0mm
