Intrinsically safe design boosts reliability, safety, productivity
The future is innovative IS solutions that meet demand for high-speed data communication
- Hazardous area systems provide an ease of installation, maintenance, repair.
- Equipment design has to meet hazardous area regulations and survive the rig-floor environment.
- Intrinsic safety concept can use existing cables and connectors, a major savings.
By Parag Shah
The current demands for drilling in the oil exploration industry include environmentally clean solutions that are efficient and safe while seeking reservoirs, which are significantly harder to access.
The challenge to service companies then is the task of integrating new technologies with increased reliability at higher safety standards.
Industry wide, management is continually challenging the operations team to minimize downtime, improve the efficiency, and lower the costs of the drilling process. For example, the set-up of the surface equipment, which typically is a six to eight hour process with the cable layout taking 70% of that time, is always under scrutiny for productivity improvement review. In addition, cabling costs are one of top three recurring expenses for field districts as well as component failures, which require quick replacements to avoid costly delays.
These circumstances necessitate the engineering groups within the organization to support the operations team by designing smaller, lighter, safer, and more reliable products.
The designers have to do that while continuously improving functional performance-by providing higher bandwidth communication between the safe and hazardous areas.
One option to overcome these challenges would be to integrate intrinsically safe (IS) designs into these systems.
Electronics on rig floor
In the last few years, the complexity of the execution of drilling services has driven the technological evolution of electronic surface equipment. From dials, gauges, and actuators, service companies have evolved to the use of high accuracy sensors, data acquisition systems, and computers.
Displaying information that enables drillers to be more efficient and accurate, logging data for proof of service, and attaining real-time information for safer drilling have become standard practices.
The rig floor environment is hazardous (explosion-prone) and replete with harsh area applications, where the equipment often sees extreme temperatures, high shock, vibration, and EMI/RFI requirements. In addition to the environmental harshness, rig hands manage the equipment, and their main priority is on getting the job done. Given these conditions, the equipment also needs to tolerate rough handling.
The rig floor environment can have various ratings of hazardous areas, which typically stem from conditions like the distance from the well, weather conditions, and obstacles. These classifications in North America are Class I, Division 1 or 2 and in Europe, Africa, and Middle East as Zone 0, Zone 1, and Zone 2.
While the optimal control of the drilling process improves with the proximity to the well, it also mandates a mechanism to respond to a down-hole event to ensure the safety of the installation as well as the personnel.
Exploration drilling is occurring in all parts of the world from the extreme cold of the Alaskan slopes to the scorching heat of the Middle East. The environment is far from ideal, with minimal protection from the elements such as direct sunlight, rain, drilling mud, high shock, and vibration.
There is inconsistent power, potential radiation, and emissions from high-powered motors and generators or even radios.
The duration of time the surface equipment resides on site varies by the service, the rig type, and the location. In some rigs, the equipment stays for months and years and in others for a much shorter period of time, even measured in days.
Since drilling operations are extremely costly, the service companies want to perform their task quickly and efficiently, with a maximum return on the productive drilling time.
Therefore, having a technical solution that enables quick equipment setup capability, quick rig-up and rig-down can have a direct impact from a financial as well as an operational perspective as it relates to the surface equipment reliability, safety, and productivity.
There are multiple versions of exploration rigs that the surface equipment must operate on such as land rigs, submersible rigs, jack-ups, and drill ships, and within each one of these rig categories there are variations that are currently in use.
On some rigs, the equipment is laid out on different levels, up to 300 feet away from the rig floor, and in other cases, it is adjacent to operation. These variations require flexible mounting and communication options.
The system designers face the challenge of choosing the right methods for equipment design that meets the hazardous area regulations in addition to surviving the rig-floor environment.
Selections of these methods have technical and financial tradeoffs that have a bearing on product reliability, safety, and productivity.
Explosion proofing: This method utilizes specially designed enclosures. The enclosure contains an explosion, internally, without causing any hazardous impact to the environment outside the enclosure. This method affords flexibility in the design of electrical circuits for power, stored energy, component selection, and the like. This is the common practice in fixed installations, but in rig-floor applications, there are several disadvantages:
- These enclosures are typically heavy, bulky, and costly.
- Since the enclosure is not explosion-proof when it is open, performing any maintenance requires the entire area to be temporarily decommissioned, which is not always possible.
- Permanent enclosures make it difficult to enhance and reconfigure equipment as well as accommodate any change in processes.
- High power components such as processors release a lot of thermal energy that needs to dissipate for proper operation and life expectancy. The typical explosion-proof enclosures are not for high power dissipation.
- The data and power inputs and outputs (I/O) take significant management expertise. Even if the I/O interface is intrinsically safe (IS), the cable connections need to go through cable glands with special cable jackets (or armored cable) to provide flame cooling or through a connector that is explosion proof.
Purging: In this method, technicians pump fresh air into the enclosure before powering up takes place. This removes the hazardous gases, hence the ignition sources such as arcs, and sparks cannot cause an explosion.
After the power up, we maintain the system at a positive pressure as compared to the outside atmospheric pressure to prevent hazardous gases from entering the system.
Just like the explosion-proof method, this method allows a greater flexibility in the design of the internal components. The purging method also allows the use of standard connectors for I/O if using the IS barriers. The non-IS signals must be connect through cable glands.
The major disadvantages in the rig-floor applications are:
- Accessibility to a clean and reliable air supply-this is often expensive and not always available in the field.
- The system has to shut down immediately upon any loss of internal pressure (air supply). This could happen in the middle of a critical operation and an abrupt system shut down may be highly undesirable.
Intrinsically safe: These designs operate at low energy and prevent electrical devices from creating arcs, sparks, or generating heat (during normal or fault conditions) that could ignite the explosive gases (or substances) present in the environment.
The term for such a system is "intrinsically safe." In comparison with the explosion proof and purging methods, there are certain limitations in the IS designs related to high power and high speed requirements. Though the problems are technically challenging, the companies with expertise in IS design have been able to solve them.
The major advantages in the rig-floor applications are:
- Flexibility in the selection of cable and connectors
- Ability to connect and disconnect the I/O connections while the unit is in operation
- Lower weight and smaller packaging as compared to Explosion-proof devices
- Inherent IS design provides excellent protection against ESD and lightning
- It is a far superior solution in terms of increased reliability, ease of setup, and global safety standards.
IS barriers are widely used to interface with sensors in hazardous areas. Barriers are available for common analog signals such as 0-5V, 4-20mA, or RS232/485 communication protocols.
There is a growing need in the rig-floor applications for the higher bandwidth communications (high accuracy sensors as well as Ethernet). However, these types of products were not available until now.
In addition to hazardous area certifications, systems should support the field operations by providing high reliability as well as an ease of installation, maintenance, and repair.
A system that has the capability of a quick rig-up and rig-down has many advantages. They are:
- Increases product reliability as fewer hands are getting in to the system for setup
- Minimizes the overhead to the drilling company
- Higher utilization of the same piece equipment on more jobs
- Shorter down time when the equipment needs replacement due to failure
Connectors: The benefit of using connectors is to ensure a quick rig-up and rig-down system. There is another important reason one should not overlook when evaluating whether to use connectors-the absence of connectors leads to the use of cable glands.
However, to be able to wire the end of the cable via a gland, one has to open the system, usually while rigging-up or rigging-down the unit in the harsh environment. Once the system is open, it is common technicians do not close the systems properly.
This, in addition to exposing the electronic components to the environmental elements, reduces the reliability of the system. While, adding connectors does create an additional point of failure in the system as well as increasing the cost depending on the type of connector required, cost containment can be effected by designing a barrier in front of the connector to negate the requirement of expensive explosion proof connectors.
Cabling: Cabling has a major financial impact on the over all system. If the output into the hazardous area is not IS, the requirements on the cables are stringent requiring specialized jacketed (or armored) cables that meet explosion proof ratings.
This results in direct and indirect costs due to several reasons:
- The cable cost is higher because of the requirement for the special jackets or armored cable. This cost suffers further by the fact that the most common damaged components of a rig-up kit are the cables and therefore the need for a requisite supply of backups.
- The cost of transporting the cable to the rig increases due to the weight, considering the average cable distance between the rig-floor to the safe area is 300 feet and the cable usually comes by the reel.
- The majority of time spent on a typical surface system installation is on the layout of cables. Service, support, layout, and the handling of armored cables make the cabling process more expensive.
The service companies have made significant investments in cables and connectors over the years. Using the existing cables and connectors would be a major cost savings. The intrinsic safety concept makes this a feasible option.
One-person operation or more
Having a system that is lightweight and compact, easy to transport to the rig site and up to the rig floor, without requiring much real estate, that is at a premium in the rig, are some of the major factors in the rig-up and rig-down process. In some cases, this can be the difference between a one-person installation and one that needs multiple people.
The latest communication trend utilizes Ethernet protocols to communicate between the data acquisition box, the rig floor system, and the company's main office. In some cases, the data beams via satellite back to the corporate location, where centralized control rooms monitor the entire activities worldwide.
Ethernet TCP/IP has become a standard protocol that has sufficient bandwidth, hardware, and software support from manufacturers, and it is becoming easier to support at all service levels.
Up to this point, there were two feasible options to run Ethernet in hazardous area:
- The fiber optic medium is safe to use in hazardous areas, since there is no electrical energy present in the fiber; however the total cost of installation between cabling and connectors as well as the difficulty and expense of maintenance does have a financial impact. For example, a complete set of industrial rated cable-connectors and cable (for quick connect) can cost up to $2,000, and repairing a broken or cut cable in the field is not feasible due to the tooling involved.
- The copper (CAT5 Ethernet cables) is used successfully in the industrial applications where IS is not required. There are hardened cables and sealed RJ45 connectors available in the market that are suitable for such applications. The major limitation of using copper Ethernet in the rig floor applications is the hazardous area certification. Recently, the solution has become available that is IS Ethernet with the features desired in rig floor application. The benefit of this solution is the ability to use standard cable and connector, quick plug-in due to use of standard connector, ease of set-up, and the like.
- The wireless Ethernet technology (IEEE 802.11 a/b/g) is still in its early stages in industrial applications, and a few organizations in the vanguard in rig-floor applications are using it. The use of wireless technology in hazardous areas requires hazardous area safety certification. There are a couple of solutions that have become available in the market recently.
By successfully designing quick rig-up and rig down systems that integrate IS technology in the systems and eliminating the requirement for purge and explosion proof technologies, we see a more efficacious solution.
We see the use of IS technology as permitting flexibility in the product packaging and system architecture, which in turn improves serviceability, transportability, and the reduction in system cost.
IS technology is at the cutting edge of the design effort to address the continuous improvements in products and services that require increased-data bandwidth for real-time information and enhanced accuracy.
ABOUT THE AUTHOR
Parag Shah ([email protected]) has a B.S. and Masters degree in electrical engineering. He is vice president technology and solutions at Azonix-Dynalco (www.azonix.com). He has two patents related to Ethernet technology.
Safety survey: Human error top culprit in accidents
By Gregory Hale
Unplanned downtime is the enemy in a manufacturing environment, but that is not the only opponent automation professionals face on a daily basis. Ensuring a safe manufacturing environment remains the top priority across the board.
Ensuring a safe environment remains a key element to any manufacturing site, and the InTech Market Study on safety shows automation professionals from all aspects of control disciplines-process, discrete, batch, hybrid and systems integration-find accidents happen and human error is usually the main culprit.
While a majority of respondents, 52%, said there were no accidents at their facility in the past year, 48% said there was some form of an accident at their plant.
In most cases, 80%, found human error was responsible for the accident, while 12% said management oversight was an issue, 6% said equipment was a problem, and 2% said there was a flaw in the process.
Safety is a mindset, and when asked what is driving their overall safety strategy, 50% of respondents said there was an increase in the culture, while 17% said standards are a driver, followed by government regulations at 11% and employee still level at 10%.
When asked if the facility had a safety instrumented system, 84% of respondents said yes, while 16% said no.
Sometimes safety instrumented systems have to be separate from the control systems, but the numbers were a bit closer than anticipated with 59% said their safety instrumented system was standalone, while 41% said it was not.
Does your safety system run in conjunction with your control system? Overwhelmingly, 74% said yes it does, while 26% said it does not.
Being aware of policies and procedures is key to any safety system; so when asked if their facility conducted regular safety meetings and/or training for its personnel, 93% said yes they did. While the actual percentage is small, 7% of respondents said they failed to hold safety training or meetings.
Systems age, and they need attention, so 56% of respondents said they have updated their safety instrumented system in the past year, while 19% said two years ago, 10% said three years ago, 4% said four years ago, 5% said five years ago, 4% said 6 to 10 years ago, and 3% said 11 years ago and above.
The top issue that necessitated the most recent update came down to age; 24% said that was the top cause, communications was the next issue at 17%, interconnectivity came in third at 13%, cost of upgrade vs. cost of future upgrades tied with other at 11%, continued viability of supplier came in at 9%, while product not supported by vendor came in at 8% and global concerns at 7%.
In terms of maintaining their safety instrumented systems, a huge majority, 77%, said they took care of things internally, while 9% said their supplier maintained the system, 8% said a system integrator handled the chores, and 5% said other.
Consistency is a good thing, and 60% said their service and support for their safety system remains consistent, while 31% said it was improving and 9% said it was worsening.
Safe and secure
With the cyber connection to safety systems, you have to ensure you are safe and secure. So, when asked if they felt their safety instrumented system was secure, 83% said yes, while 17% said no. Along those lines, when asked if they knew if outsiders ever breached their safety system, 8% said yes, while 92% said no.
Cyber is not the only area of security. When asked as to the physical, electronic, and cyber security layers, which of the following exist at your facility? Respondents said:
- Monitoring and protecting the perimeter, 15%
- Identifying and controlling who enters and exits the facility, 15%
- Tracking movements of building occupants and assets, 4%
- Controlling access to restricted areas, 14%
- Quickly locating equipment, products, and other resources, 4%
- A program to improve emergency response time, 9%
- A theft prevention program, 6%
- Integrating systems for greater speed and efficiency, 5%
- Protecting process automation networks and systems from cyber threats, 12%
- Implementing policies, procedures, and education, 16%
When it comes to physical security and safety and where respondents could give multiple answers, 41% said they use fences, 36% said they use guards, and 23% said they use barricades.
Regarding electronic security and safety, 33% of respondents said they employ access cards, 30% said they use video cameras, 25% said they use closed circuit television, and 12% said they used motion detection equipment.
When talking about cyber vulnerabilities to safety and process control systems, respondents' top choice for what their facility engages in was best practices, policies, procedures, and change management at 15%, followed by physically separated process control and enterprise networks with limited access points at 14%, physically separated process control and process safety systems with limited access points at 12%, regular risk and vulnerability assessments and disaster recovery at 11%, hierarchical architecture with cyber-security access restrictions at each network level and security hot fix and antivirus deployment strategy at 10%, high security model deployed on PCs and servers at 9%, and dedicated service team responsible for cyber security at 7%.
ABOUT THE AUTHOR
Gregory Hale is the editor of InTech magazine.
Boomers and safety strategies
One of the top issues in the last few years, not to mention the coming five years, is Baby Boomers leaving the industry.
When it comes to safety, whether Boomers are there or not, it should not affect the strategies employed by manufacturers, according to an InTech Market Study on safety.
It looks as though when Boomers do decide to call it a day and leave the industry, safety strategy will not feel the affect, with 85% of respondents saying it would not, while 15% saying yes it would.
Intrinsic safety (IS) is a protection technique for the safe operation of electronic equipment in explosive atmospheres. The theory is to ensure the available electrical and thermal energy in the system is always low enough that ignition of the hazardous atmosphere cannot occur. Ensuring only low voltages enter the hazardous area and all electric supply and signal wires have Zener safety barriers is how this can happen.
Explosion-proof apparatus is an apparatus enclosed in a case capable of withstanding an explosion of a specified gas or vapor that may occur within it and of preventing the ignition of a specified gas or vapor surrounding the enclosure by sparks, flashes, or explosion of the gas or vapor within and that operates at such an external temperature that a surrounding flammable atmosphere will not be ignited thereby (NFPA 70).
Purging is the process of supplying an enclosure with a protective gas at a sufficient flow and positive pressure to reduce the concentration of any flammable gas or vapor initially present to an acceptable level (NFPA 496).
Pressurization is the process of supplying an enclosure with a protective gas with or without continuous flow at sufficient pressure to prevent the entrance of a flammable gas or vapor, a combustible dust, or an ignitable fiber.