WirelessHART & Safety: applications that will increase your overall Plant Safety

Since its inception in 2007 WirelessHART has gained a lot of traction in typical process environments, with customers using WirelessHART to monitor pressure, temperature and level challenges. What is less known is that WirelessHART is a perfect enabler to increase plant safety. In this article we will summarize some of the typical WirelessHART solutions that can be used to increase overall plant and personnel safety. More information can be found here

Let’s take a more detailed look to some of the solutions: 

• Pressure Relief Monitoring
• Seal Pot Monitoring
• Safety Showers
• Hydrocarbon Leak Detection
• Floating roof monitoring
• Valve Monitoring
• Gauge replacement
• Corrosion Monitoring  

Pressure Relief Monitoring

Pressure Relief Monitoring is a hot topic nowadays because of the regulations around emissions and flaring. PRV’s are relatively simple devices, however despite their simplicity can cause many problems such as leaking, getting stuck open or closed, rupture disc issues and others. Leaking PRV’s is a real issue in industry, some claim that up to 40% of all PRV have more than one way of leaking.

This will result in unwanted flaring and emissions – causing loss of (expensive) product and CO2 fines. Many companies struggle with PRV monitoring as they tend to be overhauled either in a time based schedule (causing unnecessary costs), during turnarounds or when a problem is obvious (run to failure). WirelessHART is a perfect enabler to overcome the majority of these problems.

When using a Rosemount 708 Acoustic Transmitter, leaks can be detected on PRV’s. If the PRV is equipped with rupture disc they can also be monitored by using a switch that is connected to a Rosemount 702 Discrete switch indicating when the Rupture Disc blows. The Rosemount 702 Discrete Switch is also available with 2 channels which gives extra security, as it will confirm that both the inlet and outlet Rupture Discs have blown open. Optional a Wireless Pressure Transmitter can be added to detect small leaks. Because the solution is completely WirelessHART it can be quickly installed and connected to the DCS system for example.

Seal pot Monitoring - API 682 4th Edition

The latest API 682 4th edition states that it is recommended to use transmitters instead of switches for pumps based on Plans 52, 53 A, B, and C for dual seal flush systems. Most pump auxiliary seal flush systems also have limited online measurements. As with pumps, the traditional approach is manual monthly checks in the field, and switches to detect low level, high pressure, or high temperature. Therefore the use of WirelessHART pressure and level transmitters offer an excellent opportunity to increase pump life and have safe, reliable operation.

With indicating wireless transmitters, a field operator can visually monitor operating parameters at the equipment, and operators can view the same data in a control room. Data from transmitters can be analyzed to predict problems before they occur, such as watching a trend as a measured value approaches an alarm point, for example. Predicting failures before they occur can allow maintenance and repairs to be planned and made prior to a breakdown.

Safety Shower Monitoring

The majority of Safety Showers are not monitored continuously. In case of emergency the person in need of help needs to push a pedal to engage a siren or a strobe light. Sometimes safety showers are wired up to the control room / emergency services but this is rare rather than the norm. It is also expensive to install cables and junction boxes to wire all the safety showers – next to that a corrosive environment and wear/tear make a cable connection not so reliable.

WirelessHART devices combined with TopWorx GO switches will help to increase awareness to the person in need of help with accurate time & date stamp. Every safety shower can be retrofitted with this solution – both insulated and non-insulated safety showers. A Rosemount 702 Discrete Wireless Transmitter is installed on the safety shower combined with the two GO switches (head and eye wash). The solution requires no power or any other infrastructure (aside from a WirelessHART gateway). Important is that this solution complies with OHSA and EU regulations that emergency services should be within an acceptable time. Further is any event time / date stamped for audit and government purposes

 Hydrocarbon Leak Detection

The detection of leaking hydrocarbons has always been a high priority for everyone because of the associated safety hazard. Spills can go undetected and contaminate the soil resulting in high clean-up costs and damaged company reputation. Leaking hydrocarbons also represent a potential fire hazard which can result in a disastrous outcome. Since the Bunsfield (UK) explosion in 2001 regulations around tank overfill and detection methods have been introduced to avoid disasters like Bunsfield to ever happening again.

However we still sometimes see incidents with leaking hydrocarbons causing large problems. In theory every tank farm should have hydrocarbon leak detection but often this is a one-point detection method. Emerson also provides a solution to extend this detection at a fraction of the cost by using a Rosemount 702 Discrete switch transmitter combined with a Pentair TT5000 Tracetec cable. The cable is dressed around the tank and then connected to the Wireless switch. In case of a spill (or leak) of hydrocarbons the cable will detect this and closes a contact – indicating to the operator or emergency services that a hydrocarbon leak has been detected.

Monitoring of Floating (Tilting) Roofs

Floating roofs are widely used in tank storage – in general there are two types (pontoon types and double-deck type roofs). A floating roof normally floats on top of the liquid, suppressing vapours from evaporating to the atmosphere. Normally the roof follows the liquid up and down with the tank operation movements.

However, for different reasons this may not always be the case, and various conditions may affect the buoyancy of the roof. If a roof starts sinking or gets stuck it is a major safety risk with significant consequences (fire, release of hydrocarbons, large mechanical damage,...To check the integrity of the floating roof, automated methods do exist. These will eliminate the need for manual inspections and reduce exposure of people to dangerous conditions. Typically, these methods provide a ‘round the clock’ detection directly connected to the control room so any abnormality can be detected early. In general two systems can be deployed combined with WirelessHART devices: a Guided Wave Radar solution or WirelessHART vibrating forks.

Valve Monitoring

Nearly 90% of plants have experienced problems with non-automated valves within the past year. Manual actuation takes time away from process operation and opens the door for costly valve alignment - mistakes that could result in environmental leakages, lost productivity, and safety hazards. Process upset is the first indication of a malfunctioning valve remotely actuated with no position feedback.

Manually-actuated control valves depend on field operators following correct work practices to ensure all valves are in the correct position. If a valve is in the wrong position during start up, shutdown, or batch operations, the error may result in a safety hazard, environmental spill, or wasted process output. By automating that valve for example with a WirelessHART positioner, you also automate the valve alignment work practices to prevent human error. Recent developments in technology now allow an increase in the overall safety of co-workers by adding position indicators on manual operated valves. The revamping of existing (important) hand valves can be done wirelessly allowing for a quick upgrade of the hand valve without any wires. Two different types of positioners can be used, either a discrete positioner (Fisher 4310 - open / close) or a full scale range positioner (Fisher 4320 – 0 to 100%). This information can be directly transmitted to the DCS system / control room for further diagnostics.

Gauge Replacement

Many plants and offshore platforms have a significant amount of manometers – so called “gauges” and pressure switches. Those gauges often indicate temperature or pressure with a needle indicator. Due to their inherent design they fail quite often and information is stranded at the gauge. Therefore, operator rounds are introduced – recording at regular intervals pressure and temperature indications. There is a drawback with this whereby operator rounds expose personnel to hazardous risks or locations.

Gauges are also further unreliable and inaccurate. This results in a relative high data cost to capture the information and process it later in a customized system. The majority of traditional gauges operate by using a “Bourdon” tube. This tube is very fragile for over-pressure and is connected to a rather complex mechanism with gears and several moving parts. On average 25% of all gauges at any time in a plant have failed, providing incorrect or no information at all.

To overcome all the difficulties associated with the traditional gauges Emerson has developed the new Wireless Pressure Gauge (WPG). This gauge removes all the previous problems (doesn’t have a Bourdon tube) and at the same time the form factor is exactly the same as a traditional gauge. In addition, the stranded data is solved by the WPG being WirelessHART making updates to the control room up to every minute. This will also reduce the need for dedicated operator rounds when monitoring gauges.

Corrosion Monitoring

Corrosion is costing the industry millions of euros every year. Corrosion can be found in every aspect of industry, including affecting plant operations significantly. This can also result in safety hazards, explosions and product leakages. The importance of internal corrosion monitoring should not be undervalued. Corrosion of pipelines and equipment can lead towards severe safety and environmental hazards. Emerson has two WirelessHART versions (ROXAR) for measuring corrosion / sand & erosion.