Pressure Build Up Unit

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A pressure build up unit (PBU) maintains the LNG tank at the desired pressure, it's basically a two phase shell and tube heat exchanger with a pipe connection to the bottom and top side of the LNG tank.

The PBU is designed in accordance with the TEMA standard. Our heat exchanger uses a water and glycol mixture as the heating medium. We will build this heat exchanger into the tank connection space (TCS), along with the pipework and valves.


A typical LNG fuel gas supply system has one or more cryogenic LNG storage tanks. The LNG is kept at a temperature of -162°C. Two important components in the system are the vaporizer, gas heater and the pressure build up unit (PBU). The PBU keeps the tank at the correct pressure, and the gas heater heats the gas to the right temperature for delivery to the engines. The tank is filled with LNG from the bunkering station.

The LNG tank is never entirely empty, nor is it truly full. When the LNG fuel system isn’t in use, the temperature will slowly rise under the influence of the temperature outside. Because the tank is vacuum insulated, the LNG can be held in the tank for about 15 days. Using the gas as fuel for the engines lowers the pressure. Whenever the pressure drops too far, a small amount of LNG is sent to the Pressure Build Up Unit. This vaporizes and returns the gas to the top of the tank, bringing the pressure in the tank back up. The Pressure Build Up Unit is automatically triggered by the alarm, monitoring and process control (AMP) system, ensuring that the tank maintains the correct pressure at all times.


We have been in this industry since 1988, with over 700 projects completed and over 2300 KM of piping installed, we can assure you that you will get high quality products. That is what we stand for, quality! Together with our knowledge and passion about water and technology we are the perfect partner for you. Because in the end you want a good product and we want you to be satisfied.


If you want to know more about our pressure build up unit or our other services, you can easily fill in the contact form on the bottom of this page. We are always ready to answer your questions.

For more options, have a look on our page with three concepts for LNG fuel systems

Three LNG fuel system concepts

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