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There are two types of internally ribbed tubes: Multi-lead rifled tube and Optimized multi-lead rifled tube.Internally multi-lead rifled steel tubes apply as main component for heat exchange,the rotary movement of water caused by internal spiral ribs.
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:
Multi-lead rifled steel tubes main steel grades:
Multi-lead rifled steel tubes standard (Part)
GB5310-2008、GB/T 20409-2006 Chinese National Standard Multi-rifled seamless steel tubes for high pressure boiler
ASME SA-213M-2015 Specification For Seamless Ferritic And Austenitic Alloy-Steel Boiler, Superheater, And Heat-Exchanger Tubes.
Multi-lead rifled steel tubes size:
Applications of Multi-Lead Rifled tubes:
Rifled tubes are used in high pressure boilers to eliminate the steam film effect due to the D. N. B. on the inner surface of the tube and raise thermal efficiency in the furnace walls.
Rifled tubes in a conventional boiler provide a larger margin of safety for natural circulation and assisted circulation and many economical advantages as:
• Reduction of weight for downcomers,
headers, drum and connecting pipe
• Reduction of pumps power
• Reduction of framework weight