REMBE's NIMU signalling device

Claire Lloyd, Team Leader, Process Safety Europe, REMBE Safety+Control, discusses how REMBE’s intelligent signalling solution NIMU will keep operators informed about the status of their entire process while not being affected by the harsh operating conditions

Throughout the oil and gas Industry, processes operating at high temperatures and with highly corrosive process media are common.

Traditional signalling devices were not always compatible with such conditions and, therefore, are often over-looked like an additional accessory to monitor the status of the rupture disc.

Developments in technology mean even companies in this sector can now use rupture disc signalling systems, helping not only improve productivity and safety but also supporting with environmental concerns.

German manufacturer REMBE is a European leader in the manufacturing of pressure relief devices and explosion safety systems and its product range encompasses some of the most robust rupture discs and signalling solutions available to add significant operational value within the chemical industry.

For processes operating with potentially harmful media, the ability to shut down the process quickly and safely means the risk of leakage is eradicated.

Complying with explosive atmospheres and intrinsic safety industry standards, the signalling devices are designed to provide rapid notification of rupture disc activation, helping ensure safe management of the process while minimising downtime.

REMBE’s signalling devices — like the non-invasive monitoring unit (NIMU) — can easily be integrated into customers control systems to provide visual or acoustic notification of disc burst or to shut down the plant where required.

With non-invasive signalling devices, which make it impossible for the process medium to escape, processes with critical pressures and demanding media can also be reliably monitored.


Customers for whom compatibility with harsh operating conditions is of paramount concern, NIMU is a reusable rupture disc signalling system designed for rapid notification of rupture disc activation even in the harshest environments and corrosive environments.

The REMBE NIMU sensor is not in contact with the process, meaning it is not affected by challenging process conditions or corrosive media.

The intrinsically-safe NIMU is installed into a tapping within the outlet of the rupture disc holder, completely isolated from the process, so it does not create any leak paths and is not damaged following disc activation — critical for chemical customers where leak paths cannot be tolerated.

The double disc assembly

With the traditional membrane type signalling devices, false alarms were unfortunately common place, since the harsh operating conditions could cause the device to activate even if the disc itself had not opened. This false signalling would cause unnecessary and costly process downtime.

In offshore environments, rupture discs are often in difficult-to-reach locations, so false activations are extremely problematic.

Unlike these traditional devices, the NIMU is not negatively affected by the process.

Additionally, membrane detection systems are single use, meaning additional replacement costs.

With the NIMU, this additional cost is eradicated. The NIMU enhances overall dependability of rupture disc installations while reducing long-term expenditure.

NIMU signalling device

Not only is the signalling device fully reusable following disc functioning, it is also reusable after routine maintenance checks.

Easy to inspect during such maintenance routines, NIMU’s closed circuit design allows it to be refitted into the holder by the same operator inspecting the disc, simplifying and quickening the maintenance process — a must to meet the demanding productivity requirements within the chemical processing sector.

When used in combination with the REMBE IQ Safety Cockpit, the operator can be instructed in the event of a system disruption and can implement the relevant emergency management protocols.

The affected employees can be individually informed of a process shutdown and a response coordinated to identify the cause and get the plant back up and running as quickly as possible.


Rupture discs installed on a gas compressor module are designed to protect the tubes on a heat exchanger from rupturing due to overpressure.

Rupture discs are selected due to their response time in milliseconds. As output is directly correlated to the production from the compressor module, it is critical that a rupture disc with good life cycling capability is installed, otherwise as the operating pressures increase, the rupture disc will be pushed to its operating limits and fatigue causing frequent failure and unnecessary loss of production through downtime.

The vent lines of several heat exchangers and other equipment are typically connected to the flare system with a common manifold to save space on deck.

This leads to the fact that there is variable back pressure on the rupture disc protecting a heat exchanger.

This situation requires a double disc assembly. The first rupture disc is designed is to protect the heat exchanger shell against excessive overpressure in case of tube rupture.

The second disc is typically a forward acting disc designed to resist the back pressure and is set at differential pressure than the required relieving pressure of the first disc less the amount of maximum back pressure.

Conventional signalling devices, which are invasive, are not suitable for such a harsh environment since they would be wetted by the medium on the downstream of the second rupture disc.

Engineers designed a version of NIMU for such double disc assemblies and a special design for forward acting rupture discs to provide a reliable and long-life signalling device for demanding applications in the offshore industry.

This way, in addition to the first disc, the second disc’s condition could be continuously monitored improving the safety and reliability of the processes on FPSOs.

Most people associate REMBE with REMBE Safety+Control, the specialist for explosion safety and explosion venting worldwide.

Headquartered in Brilon (Hochsauerland, Germany) and with approximately 300 employees worldwide and numerous subsidiaries (Italy, Finland, Brazil, the US, China, Dubai, Singapore, South Africa, Japan), the company offers customers cross-industry safety concepts for plants and equipment. All products are manufactured in Germany and meet the requirements of national and international regulations.

REMBE customers include market leaders in various industries, including the food, timber, chemical and pharmaceutical industries.

The company’s engineering expertise is based on almost 50 years of application and project experience.

As an independent, owner-managed family business, REMBE combines expertise with the highest quality standards and is involved in various specialist committees worldwide.

Short coordination paths allow for quick reactions and customer-specific solutions for all applications, from standard products to high-tech special designs.

In addition to REMBE Safety+Control, four other companies operate under the REMBE umbrella brand: REMBE Research+Technology Center, REMBE Advanced Services+Solutions, REMBE Kersting, and REMBE FibreForce.