(Quick change type)
Impeder clusters offer an economical alternative to individual impeders for tube sizes over 150mm (6") Clusters are available in many configurations for tube & pipe sizes from 3" to 24" in diameter. EHE's Quick Change system uses Parker quick connect couplings to facilitate rapid replacement of the impeders, often without having to cut the tube. The Quick Change fittings also eliminate damaged threads & impeder alignment problems.
Welding larger diameter tubing does not usually require impeders to completely encircle the tube I.D., so larger clusters consist of two arcs of impeders positioned close to the top inside surface of the tube.
Cluster assemblies consist of an aluminium manifold with clamping system to mount the cluster on either standard pipe, or on most types of internal scarfing mandrels. Also included is a spacer plate to maintain correct alignment of the impeders. Coolant connection is by means of flexible hose or copper tubing. Return flow cluster assemblies are also available as an option.
Impeder clusters may use either 22mm or 31mm impeders, in all common lengths and range anywhere from 3" diameter up to about 21" diameter
(Rectangular Bar Type)
The key element in welding large diameter tube & pipe using high frequency induction, is to have efficient impeders & work coils. Some modern solid state welders use lower frequencies to achieve proper impedance matching to large work coils. This increases the demands on the impeder assembly, and requires that a greater mass of ferrite be present in the top portion of the tube.
EHE's modular clusters use rectangular bars of ferrite in special heavy duty rectangular covers, to concentrate the ferrite in the area of the tube where it is most effective. The massive ferrite bars are also highly resistant to damage, resulting in longer impeder life & reduced operating costs.
These impeders are attached to the outside surfaces of two identical aluminium manifolds. This system protects the manifolds from damage caused by welding spume. Many newer tube & pipe mills use carbide tipped cold saw cutoffs, which may require a relatively dry tube I.D. This can be easily accomplished by using modular clusters in a return flow configuration.
Modular clusters of rectangular impeders cost about the same as conventional impeder clusters, but place up to twice as much ferrite in the weld area, for higher efficiency in the 80-200kHz. frequency range.