HYDROSWAGE® SYSTEM EXPLAINED
The HydroSwage® System
is an innovative approach to hydraulically expand heat exchanger tubes into tube-sheets through the direct application of high internal hydraulic pressure within an established expansion zone.
A Tube-Loc™ Drawbar
quickly positions and sets the tube into the tube-sheet prior to HydroSwage® expansion. It is also used to set tubes prior to welding.
Water Pressure from an air driven pumping system is intensified to the desired high pressure. It is transmitted through a small bore, flexible high pressure tube to a lightweight hand-held mandrel holder. Amandrel, which latches into the mandrel holder, directs the pressure to the inside diameter of the tube and is held within an accurately prescribed pressure zone. Pressure is contained within the expanding tube by a soft elastic seal which is supported by a patented elastic backup and an expanding segmented steel ring. Pressure is applied over the full length of the joint in one step. The pressure zone is accurately adjusted which reduces the damaging crevices at the edges of the tube sheet. Stress, crevice corrosion, and metallurgical changes are thus minimized.
Direct Hydraulic expansion with pure water produces clean joints. Lubricant is not forced into the tube surface, and there is no surface flaking or spalling inside the tube.
A Smooth Transition from expanded to unexpanded areas, along with no change in tube material properties, greatly reduces strain hardening, tube fatigue and stress induced corrosion cracking. Tube wall thickness and tube length change is minimal. Before
contact is made with the tube sheet, a small reduction in tube wall thickness and length occurs because a constant volume of tube material is expanded to a larger diameter. However, no change occurs during the high pressure swaging, eliminating the shear
strain and loss of seal between tube-sheet that is a characteristic of roller expanding.
The HydroSwage® tube expansion cycle is automatic and initiated by the operator button located on the mandrel holder. The tube is filled with distilled water at a low pressure, intensified to the higher setting and held for the time required to accomplish
a stable plastic condition of the tube. This dwell time is essential to stabilize exotic tube materials. After the pressure is released, water is drained back into the reservoir. All of this occurs in a period of a few seconds.
Actual Expansion Pressure at the tube is read on theMark V touch screen. An adjustable “under” and “over” pressure condition and operating sequence is also shown on the touch screen as well as the operator mandrel holder. To assist with quality control records
the Mark V system can store expansion history that can be downloaded to an Excel spreadsheet through the USB port located on the electrical chassis. Analog connections are also provided for strip chart recorders.