A reliable sealing solution was needed for a water-based hydraulic system. The system controlled the operation of a dredging vessel’s hopper doors, which are located in the boat’s hull. Proper door operation ensured the doors were securely closed when filled with debris, and that dredging materials would be deposited in the correct location when doors were opened. Should the doors’ functionality become comprised, operations would stop and there was the potential for severe penalties.

Seals were needed in multiple cross-drilled ports within the hydraulic system’s logic block to control water flow between the pilot valve and a large poppet valve. While the marine application presented temperature extremes and environmental concerns, the hydraulic system also had unique spatial challenges, as the system was being developed to be smaller and more compact than the previous model.

While SAE type plugs had been used in the previous logic block, plugs with correct pressure performance capabilities were too large in diameter for the new design. The customer also noted that the SAE plugs required specific monitoring and inspection. Dredging operations created regular vibration and shock, as materials were emptied onto the doors with great force, and instances had been identified where the SAE plugs had begun to back out from the port.

SFC KOENIG engineers worked with the customer from the early stages of the hydraulic system development. Multiple KOENIG EXPANDER CV series plugs were selected, which exceeded pressure requirements and fit the smaller port configurations. The CV 173 models were constructed with an aluminum sleeve, so the plugs would not corrode with the base material, react with water in the hydraulic system or be affected by potential exposure to the exterior environment. While both 6.0mm and 10.0mm models were ultimately used in the system, parts were available as small as 3.0mm to as large as 22.0mm in the series, which provided flexibility as designs progressed.

In the previous design, space was needed between each channel to increase the strength of the base, to prevent cracks and damage that could occur from thread tapping processes and the rotational torque applied in the SAE plug installation. SFC KOENIG worked with customer engineers and advised on channel configurations and pressure considerations as they related to the sealing plugs, which allowed for a new channel design that reduced the size of the base. In addition, assembly operations were analyzed to develop ideal pressure settings, tooling alignments and installation processes using SFC KOENIG air hammers.

While size and space were the primary reasons for the switch from SAE plugs, KOENIG EXPANDER components also provided many benefits related to installation, which were fully realized during the engineering process. SAE plugs required additional drilling and tapping operations, which generated metal debris and could potentially cause contamination. Comparatively, the serrated sleeve of the SFC KOENIG component expanded into the base material when installed – no metal chips were created and a secure, leak-proof seal was formed that did not require sealing compound. Additionally, the elimination of thread tapping also eliminated the risk of cross tapping.

In the final design SFC KOENIG engineers were able to help optimize sealing plug size and installation forces, which reduced the size of the hydraulic system and resulted in a leak-free seal that could resist vibration and would remain permanently secure. KOENIG EXPANDERS plugs reduced installation time and effort required in installation, and lowered total costs.

After 5 years of use, the new water-based hydraulic system has recorded no problems due to seal failure, and the reliability of KOENIG EXPANDER models has reduced maintenance and downtime. Installation of the SFC KOENIG components is also faster than the SAE plug installations, which has reduced assembly time and costs. The plugs have been integrated into other hydraulic systems produced by the customer, and KOENIG EXPANDER plugs are now the preferred sealing solution.

The customer noted that the engineering support provided by SFC KOENIG was integral in their ability to successfully reduce the size of the hydraulic system, and that the design process provided on-going communication and support, which reduced the time required to bring the project to completion.

Technical Details

› Application: Water-based hydraulic system for marine vessel
› System Pressure: < 100 bar
› Fluid Medium: Water
› Product: CV173 Series Plug
› Volume: 10,000 Million

Product Overview

› Model: CV 173-070
› Style: Push Style Expander Seal
› Sleeve Material: Aluminum 2024-T4, QQ-A 225/6
› Ball Material: Stainless Steel, AISI 302/304, Wax Film Lubrication
› Pressure Capabilities: Up to 170 Bar
› Sizes Available: 3.0 to 22.0mm in diameter