An undersea cable company was looking for a firm to design and build a high-pressure mixed gas system to pressure test the various undersea components they manufacture.  These components are installed into high-pressure vessels and externally gas-pressurized to 2 main pressure setpoints – 15,000 psig or 5,000 psig, and these components are required to pass both a pressure test and a trace gas leak test.  They called on Optimation to design, build, test, and install the system at their site.


Optimation designed and procured equipment, instruments, piping, electrical/control components, and wrote software recipes to assemble a test system in our shop and commission it with the client present.  Once the system passed the Factory Acceptance Test (FAT), it was disassembled and shipped to the client’s site for installation and final Site Acceptance Test (SAT).

The new test system consisted of high-pressure equipment, instruments, and controls to make a mixed test gas containing trace amounts of Helium (He) in it and store the test gas in large storage tanks in the test room.  As the test was conducted, the system would pressurize up and down with various hold periods in the test as the control system looked for drops in pressure, indicating a leak somewhere.  There were also downstream He leak detectors that would detect minute traces of He if a test component had a microscopic leak that could not be picked up from the pressure trace curves.  The complete test sequence was automated and controlled by a programmable logic controller (PLC) with a personal computer and HMI software serving as the operator interface.

There are multiple hardware and software components to a high-pressure test system, with the main one being the high-pressure patch panel, a pressure supply assembly for the Unit Under Test (UUT).  Design started with agreement on the P&ID, which lays out the system functionality and flow path.  From there, a 3D model was created so Optimation and our client can see what the future panel would look like.  The photos below showing the design drawing and the actual panel built in our shop:

When all subsystems have been assembled, they are then connected mechanically and electrically to each other, as well as to the site utilities.  Below is a picture of how this equipment was laid out in the Optimation shop prior to the client’s FAT.  Note the high-pressure tank in the middle of the equipment layout – this was used to simulate a UUT so that all components could be put through hardware and software testing together.

After successful testing in the Optimation shop, the equipment was then disassembled and shipped to Client’s new High-Pressure Test Lab, where it was reassembled and hooked up to their site utilities.

Below is a rear view site layout drawing of the test room, and where all the equipment was to be installed:

Here is a picture of the individual equipment that was installed:

Here is a picture of the operator station, where the system is monitored and controlled.  The system PFD, Process Monitors, & Recipe Control is on the left monitor, and this screen has all the critical operator-controllable components. The right monitor shows the pressure trace, which has a recipe involving a fast pressure up to set pressure, a short hold time, and then a longer bleed off sequence to atm pressure.


The new pressure test system was successfully installed and turned over to the Client in January 2021, approximately 15 mos after PO receipt, and has been in operation ever since.  The Client’s products are tested daily, and they provide pressure-tested/certified equipment to their end customers, where they will be used deep in the world’s oceans.

Final Note:

In case you are wondering why undersea components need to be tested at such high pressures, see the table below, which shows the extreme pressures our Client’s components need to withstand at the bottom of the ocean.

Ocean Where Location Depth (ft) Press at ocean floor (psig)
Atlantic Milwaukee Depth NW of Puerto Rico 27,493 11,910
Pacific Challenger Deep Southern end of the Mariana Trench, several hundred kilometers southwest of Guam. 36,070 15,630.