Alloy ferrules that protect tube ends, welds and tubesheets in waste heat boilers and process gas coolers.
A metal ferrule is the low-cost part that wears so the tube does not.
It works as long as the gas stays within the limits of the alloy.
Metal ferrules are the better choice when the inlet gas stays below about 1,650 °F (900 °C), abrasion is mild and you want a low-cost part that is easy to replace at each outage. They protect the tube end, the tube-to-tubesheet weld and the tubesheet in waste heat boilers, process gas coolers and heat exchangers. Above that temperature, or where metal dusting, carbon monoxide corrosion or heavy abrasion attack the alloy, a ceramic or hybrid ferrule lasts longer.
Many boiler tube failures begin at the tube inlet, at the weld or at the tubesheet. These spots see high gas temperature, thermal cycling, vibration, corrosion and erosion at the same time.
A metal ferrule extends into the tube and can be flared to the tube inside diameter. The gas enters through a smooth transition and passes the weld instead of hitting it. In service, the ferrule:
A metal ferrule is a sacrificial part: its job is to wear in place of the tube, and the right alloy is the one that lasts to your next planned outage.
Each ferrule is made for one boiler, to its tube dimensions, installation method and process conditions.
Flared or tapered ends that guide the gas into the tube and lower the pressure drop.
Features that set the depth of the ferrule in the tube and hold it in place, with custom outside and inside diameters.
Fiber around the outside diameter insulates and prevents metal-to-metal contact between ferrule and tube.
A precast ceramic head in front of the tubesheet adds insulation without cast refractory.
The right ferrule material depends on temperature, chemistry, gas velocity, erosion, thermal cycling and the service life you need.
Blasch makes metal ferrules in low carbon steel, 300 series stainless steels, Hastelloy and Inconel alloys. The choice follows the gas temperature, the chemistry and the erosion risk, with Inconel as the usual step up for high temperatures.
Search results for boiler tube protection mix two different parts. A tube shield is a half or full shell clamped or welded onto the outside of a tube in the gas path, for example in a superheater, where it takes erosion from ash or soot blowing. A ferrule sits inside the tube inlet at the tubesheet and protects the tube end, the weld and the tubesheet. This page is about ferrules.
Thermal oxidizers, catalyst coolers, condensers, falling film heat exchangers and nitric acid boilers in refining and chemical processing. Hydrogen reformers, ammonia combustion boilers, autothermal reformers and syngas coolers in hydrogen and ammonia plants. Where particles rather than heat wear the tube end, silicon carbide boiler tube ferrules are the alternative.
Up to about 1,650 °F (900 °C) gas temperature at the inlet, as a rule. Above about 2,300 °F, an all-ceramic ferrule is the recommended design. In between, the alloy and the chemistry decide.
It insulates the tube end and keeps the alloy sleeve from rubbing directly on the tube wall.
Yes. They are designed as an economical part that is swapped at an outage, so the tube and the weld behind it stay intact.
No. Tube outside diameter, wall thickness, gas temperature and chemistry are enough to start.
Send the gas temperature, the chemistry and the tube size. A Blasch engineer tells you whether metal, hybrid or ceramic ferrules fit.
