XID, or X-ID boiler technology refers to internally augmented boiler tubes that feature helical ribs embossed on the inside of the tube to provide increased surface area and increased heat transfer for gas flowing inside the tube of a firetube boiler. These internal spiral ribs cause a complex boundary layer separation and reattachment phenomenon.

The combined depth of tubing wall and ribbing is above minimum wall specifications and delivers a tested inside transfer rate of up to 85% greater than plain tube. The design of the tube gives it more “heating surface” than a standard tube and transfers more heat into the water from the hot flue gas as well. Because XID tubes add more heating surface and transfer more heat, they reduce the need for additional heating surface of the overall boiler. This allows a smaller physical foot print, ideal where space is limited.

First developed in 1990, X-ID tubes are fabricated by a number of boiler tube manufacturers to meet ASME standards for all material, dimensional and testing requirements set forth in SA-178A specifications.
X-ID tube is available with outer diameters (OD)  1-3”, with wall thicknesses from .065-.120 MW and tube lengths of up to 70’.

Boiler Efficiency Improvement with X-ID Tubes
The more efficient a boiler is, the more steam can be produced per unit of fuel.

As X-ID boiler tube technology improves transferring the heat content of the fuel into the boiler water, more heat can be absorbed to the lower the flue gas temperature and produce greater operating efficiency (the ratio of heat output against heat input). Case studies have shown that XID tubes can add additional 4%+ to boiler fuel efficiency.

In addition to greater efficiency, other key benefits include:
 

• up to a 20% cost savings over bare tube designs
• increases steam-volume capacity
• improves steam quality
• reduces space requirements (footprint)
• reduces fuel consumption
• lowers NOx emissions

XID boiler tubes are becoming more common every day. If you are considering a new boiler purchase or boiler retubing project, X-ID tubes can be a cost effective upgrade to your steam plant operation.