The Problem

Natural gas extraction produces byproducts -- including water, oil, and other hydrocarbons -- that are usually stored in holding tanks while the gas is piped along for further processing. Because of the geographically remote location of the typical gas pad site, the cost of monitoring and removing the locally stored byproducts can be quite high.

Traditionally, oil and gas companies have relied on scheduled maintenance to monitor the condition of extraction equipment and empty storage tanks. But maintenance schedules and byproduct creation schedules rarely coincide -- to ensure continued operation of the gas pad, companies err on the side of caution, sometimes arriving to remove only a quarter of a tank or less.

Meanwhile, technicians following the tenets of preventive maintenance visit gas pads on a regular schedule to perform upgrades and repairs, whether needed or not. This can also result in operational inefficiencies.

The Company

The Rosemount measurement division of Emerson Process Management is responsible for the measurement and analysis of industrial equipment for companies worldwide in industries including chemical, oil and gas, power, pulp and paper, food and beverage, and pharmaceutical. A major international petrochemical company and longtime customer asked Rosemount to help it better monitor tank levels and also to improve the efficiency of its facility maintenance operations.

The Challenge

Rosemount was tasked with upgrading, installing, and networking the array of sensors required to monitor conditions at the customer's gas pad facilities. Networking these sensors -- which monitor pressure, temperature, volume, and other conditions -- proved to be a challenging task. While running wires was cost prohibitive, environmental conditions were less than favorable for many typical wireless technologies. Without proper accommodation, dust and rain in particular can significantly impact wireless network performance -- and most of the equipment used in gas extraction facilities is outdoors, exposed to the elements. (Shown here, wireless-integrated sensor equipment that could be deployed in an industrial environment to remotely monitor temperature or other conditions in the process industry.)

The original peer-to-peer wireless network topology Rosemount investigated proved ineffective. A more robust network topology was required -- one that could compensate adequately for the weather while still allowing Rosemount to minimize costs by avoiding the need to run networking and power cables.

The Solution

Rosemount turned to Massachusetts-based Millennial Net, a developer of industrial-class wireless sensor networking systems. The two companies coupled Millennial Net's already power-efficient design with solar panels and the necessary sensors and housing to create completely self-sustaining, wireless-enabled sensor devices. The energy-independent design of the sensor modules alleviates the need to run power cables or replace batteries -- the solar panel trickle charges the batteries in both devices, keeping the power running even in the most extreme, RF-unfriendly weather conditions.

Sensor modules were installed at key locations to monitor byproduct tank levels, equipment temperatures, and other critical operational data. Millennial Net's wireless mesh network propagates data from sensors monitoring tank levels and equipment temperatures to a control station and satellite uplink, allowing the petrochemical company to have up-to-the-minute data on gas pad operations.

Fan belt and bearing temperatures are closely monitored by the petrochemical firm for leading indicators of potential problems, which trigger a maintenance visit and any necessary repairs. Millennial Net's wireless sensor network system is helping Rosemount's customer implement predictive maintenance and significantly reduce operational costs.

By installing the right sensors, backed up by a robust industrial-grade wireless sensor network, Rosemount has been able to cut costs and improve operational efficiencies with minimal capital expenditures.

A preventive maintenance strategy assumes equipment is relatively reliable until, after some period of time, it enters a "wearout" zone where failures increase. To postpone this wearout, equipment is serviced on a calendar or runtime basis -- whether it needs it or not. Preventive maintenance is not operationally efficient, however, for several reasons:

• Poor "wrench-time to bench-time" ratios. Wrench-time for most preventive maintenance operations hovers around 30%, according to research from Emerson. With best practices, this can increase to as much as 50% -- still far from optimal.


• "If it ain't broke . . . " However well-intentioned preventive maintenance is, it still violates the old engineer's maxim. Improper reassembly of parts can lead to accelerated failure rates.


• Jumping the gun. To avoid costly operational interruptions, preventive maintenance relies on very conservative estimates of operational lifecycles, usually leading to the replacement and maintenance of equipment before it is really necessary.


• "The best laid plans . . . " Industrial equipment failures rarely happen on cue: research from Emerson found that only about 6% of equipment follows a time-based "wearout" pattern. For most other equipment, failures typically result from the cumulative effects of events or conditions that can occur at any time. That means schedule-based preventive maintenance can also come too late, after the damage has begun.