Low temperature stainless steel shutoff valves are utilized for on/off control of fuel gas within gas fuel trains in process heating system burners. These systems are widely used by oil-and-gas firms and original equipment manufacturers (OEMs) that operate or produce gas heating equipment or burner management systems (BMSs) in upstream pipelines and tanks.
Over the last few years, North American oil-and-gas output has been climbing substantially. U.S. natural gas and crude oil production were up 10 percent and 13 percent, respectively, from 2017 to 2018.1 Drilled and completed wells rose about 50 percent during the same period.2 And, this activity has been driven by crude-oil prices that climbed from about $30 per barrel in 2015 to $60 per barrel in 2018.3 This surge has oil-and-gas producers replacing outdated process heating systems in their upstream production facilities.
For shutoff valve manufacturers, oil-and-gas process heating presents a challenging application. Environmental conditions at the point of use often are difficult. In addition, valves must deliver reliable operation despite constraints ranging from power consumption to service availability. Conversely, outdated controls can pose problems — including poor performance, noncompliance with current regulations and triggering of environmental concerns.
In recent years, of solenoid valve technology has been changing the shutoff valve landscape. Modern designs provide process heating systems with robust, durable performance and assist with safety and regulatory compliance — all while increasing efficiency and productivity.
Solenoid valve technology provides process heating systems with robust, durable performance. Solenoid valve designs can assist with safety and regulatory compliance while increasing efficiency and productivity.
Pneumatically Operated Safety Shutoff Valves
A safety shutoff valve plays a crucial role within a process heating system. Simply put: if the valve does not work, neither does the heater. And, heater failure can quickly have a mission-critical impact: slowing or halting oil or gas flow in a pipeline, preventing offloading from tank to truck, or stopping separation of particulates from extracted heavy oil.
Historically, pneumatically operated shutoff valves have been applied to this mission. But some OEMs and users are growing dissatisfied with this dated technology. These units require pilot valves for control and require other equipment and piping that add expense. Because pneumatically operated valves often use casing gas from the well to operate, they exhaust methane (a greenhouse gas) to the atmosphere when opened and closed. This burdens user companies with large carbon footprints that work against efforts to make oil-and-gas processing greener.
The relatively high power consumption of the valves is ill-suited for remote pipeline or wellhead tank locations. Many are not designed to cope with the broad range of supply pressures that differ from site to site on pipeline- and tank-heating applications. Finally, many installed systems using older valve technologies fall short of complying with modern safety regulations.
Over the last few years, North American oil-and-gas output has been climbing substantially. U.S. natural gas and crude oil production were up 10 percent and 13 percent, respectively, from 2017 to 2018.
Benefits of Solenoid Shutoff Valves
Facing increasing environmental, cost and safety pressures, North American oil-and-gas operators are replacing pneumatically operated shutoff valves with shutoff valves based on solenoid technologies.
Solenoid shutoff valves are designed to provide a number of benefits:
- Compliance with safety regulations.
- Greater environmental responsibility by not venting gas to the atmosphere.
- Higher reliability and longer service life in harsh environments.
- Reduced initial and lifecycle costs, achieved by requiring less supporting equipment and lower maintenance levels.
- More efficient operation with reduced energy consumption and increased equipment uptime.
While designing valves for oil-and-gas process heating has proven challenging, industry efforts have created products that offer benefits compared to pneumatically operated valves.
Low Temperature Operation. Maintaining tight fuel shutoff in the low temperatures at many oil-and-gas production sites represents a demanding challenge. Doing so while meeting strict regulatory approvals is even tougher. Also, the remote locations where these valves are utilized make servicing or replacement exceptionally difficult. Pneumatic controls have long struggled in these conditions.
Solenoid shutoff valves are rated for the range of operational temperatures likely to be encountered at remote locations. These valves can be tested in low temperature chambers to ensure performance down to -40°F (-40°C), to deliver reliable operation in frigid environments.
Wide Pressure Range. When specifying gas shutoff valves, buyers should pay special attention to operating pressures. Some solenoid valves require a pressure assist to open and stay open. If the pressure supply to the valve falls below this minimum pressure differential (often about 3 psi), the valve will close, thus shutting off heat to the pipe or tank. The problem: some process heating sites have inherently low supply pressure. In these locations, solenoid-based shutoff valves requiring a pressure assist may struggle, causing nuisance shutoffs, or fail to operate at all.
By contrast, valves with lower maximum pressure ratings may be poor fits for sites with high supply pressures. Make sure the valve’s maximum operating pressure rating suits the pressures of the heating system.
If multiple wells have differing pressure requirements, make sure valves can provide satisfactory service across the widest possible range of operating pressures. Some solenoid valves are rated to operate with zero minimum differential pressure — a definite plus in environments characterized by low supply pressure.
Valves that handle a range of pressures may allow some users to reduce component sizes. Downsizing the fuel train can yield cost savings.
Low Power Consumption. At remote oil-and-gas installations, electricity often is in short supply. Valves may draw power from generators, solar arrays or battery packs. Also, valves that do not use wellhead gas for pneumatic power require added equipment such as compressors, filters, regulators and lubricators. As a result, control equipment that minimizes power consumption is highly desirable.
Some valve manufacturers have engineered their valves to cut power consumption for remote applications. Some solenoid shutoff valves have peak-and-hold technology that sustains power draw as low as 0.5 W. At this level, it is possible for operators to consider downsizing solar panels or batteries.
Maintaining tight fuel shutoff in the low temperatures at many oil-and-gas production sites represents a demanding challenge. Doing so while meeting strict regulatory approvals is even tougher.
Solenoid Valves Benefits
Before processing, most gas contains impurities or entrained particulates. These pose problems for reliable shutoff operation. While few, if any, solenoid valves can handle truly dirty gas, some solenoid valves have more forgiving designs. Shutoff valves that are fitted with an optimized internal pilot orifice are designed to perform reliably with wellhead gas.
Proof of Closure. Safety regulations in many jurisdictions require that valves utilize proof of closure (POC) when used in burner systems with certain firing rates. With POC, an electrical contact is provided when the valve seal is in the fully closed position, enabling an electrical signal (contact closure) to be interlocked with the controller safety circuit. Confirming the valve’s closed position is an important consideration when starting and stopping larger pipeline- and tank-heating systems.
On burner systems up to 5 million BTU/hr, many regulations require two shutoff valves used in series (for redundancy), or one shutoff valve with POC. Burner systems from 5 million to 12.5 million BTU/hr typically require two shutoff valves in series, one with POC. Burner systems above 12.5 million BTU/hr typically need two shutoff valves in series, both with POC.
Until recently, POC was available solely in actuated valve packages. To address the needs of oil-and-gas processors, low temperature stainless-steel solenoid shutoff valves with POC are now available. These shutoff valves help increase savings, performance and production efficiency.
Regulatory Compliance. In North America, governments have been tightening regulations of burner management equipment and increasingly demanding third-party validation. This makes it imperative to consult with the manufacturer or supplier to ensure that gas shutoff valves meet all appropriate certifications for application and location.
For example, in Canada, safety shutoff valve standards and regulations include CSA B149.3-10 Field Approval for Fuel Related Components; Automatic Gas Valves Z21.21 CSA 6.5 C/I; C22.2 No. 139 Electrically Operated Valves; and ANSI/ISA 12.27.01 Single Seal. Valves also require Canadian Registration Numbers (CRNs) and must meet provincial inspections. In the United States, valves are primarily governed by Underwriters Laboratory (UL), Factory Mutual (FM) and National Fire Protection Agency (NFPA) standards.
Users can also help ensure compliance and reliable performance by making sure valves are properly tested. Query a prospective supplier about its valves’ development and testing regimen:
- Is it extensive?
- Does the valve maker test all production units or only a few?
- Does the manufacturer subject tested units to extreme conditions?
- Do tested conditions match those found at the sites?
Tightening regulations, continuing safety concerns and industry-wide efforts to achieve greater efficiency are all fueling a move from pneumatic to solenoid shutoff valve technology in process heating system applications. Fortunately, ongoing improvements mean this category now offers many excellent products that deliver innovative performance benefits.
Evaluate how well a prospective valve meets site and application needs for low temperature performance, wide pressure ranges, power consumption savings, proof of closure, regulatory codes and approvals and more. With careful selection, it is possible to choose a solenoid safety shutoff valve that provides a process heating system with regulatory compliance and safety, reliable performance and savings.