Steam systems, most often located in industrial settings, are large consumers of natural gas. In the state of California, industrial natural gas consumption has been higher than any other end use for the past few years and is therefore a prime candidate to target for natural gas efficiency measures (U.S. Energy Information Administration 2020). Steam traps are a mechanical valve that separates live steam from condensate and non-condensables (e.g., air). Most steam traps have moving parts that degrade over time and eventually fail. Solid contaminants in the steam system can also clog steam traps and result in failure in a partially open condition. When steam traps fail in the open position or leak, steam is vented into the atmosphere through the condensate return system resulting in the loss of significant amounts of energy and treated water.
Automatic steam trap monitoring through fault detection diagnostics (FDD) provides a method that reports any failure instantly and eliminates the labor required to manually check the steam trap(s). Steam trap monitoring systems are available from multiple sources including the manufacturers of steam traps and manufacturers of industrial and building controls.
Automatic steam trap monitoring systems use steam trap fault detection sensors which monitor the conditions of the traps and upon detection of a fault, send a signal to the central steam trap monitoring system. The central steam trap monitoring system then transmits an alarm to the facility operator, identifying which steam trap has registered the fault. Data collected can include temperature, ultrasonic signals, and other information that makes it possible to diagnose steam trap malfunction. Wired or wireless systems can be used to remotely transmit signals that report the trap condition. Signals are received by a central software application that measures, monitors, and manages this information. This enables plant operators to capture real-time steam trap operation data and quickly correct malfunctions.
Strainers in steam distribution system are mechanical in-line pipe fittings housing a metal screen which filter and separate solid matter allowing steam and condensate to pass through. Blow-off, or blowdown, valves in steam distribution systems are mechanical valves periodically vented to the atmosphere, discharging all solids which had been separated and captured by the strainer. Installing strainers and blow-off valves upstream of steam traps increases steam trap life and renders it less likely that the steam trap would experience a failure. This code proposal would codify steam system best practices for installation of strainers and blow-off valves in addition to automatic steam strap monitoring.
The proposed code change to Section 120.6 includes two mandatory compliance requirements, 1) the installation of steam trap FDD and 2) steam trap strainer installation (includes strainer and blow-off valve installation upstream of a steam trap). This measure would apply to all new construction, all additions and all steam trap alterations that meet the proposed code requirements. The proposed code change impacts the largest natural gas end uses in California: all covered process steam systems, including oil and gas producers, food processors, healthcare facilities, pharmaceuticals and manufacturing operations that use steam traps with connected steam line operating pressures greater than 30 pounds per square inch gauge (psig) and with total combined connected boiler input capacity rating greater than or equal 2,000,000 Btu/hr (2.0 MMBtu/hr). The proposed code does not impact space heating or domestic hot water heating applications. The total combined connected boiler input capacity rating exception is intended to trigger the measure code for sites that would replace a significant number of steam traps and thereby generate a significant savings potential due to the energy-intensive usage of process loads and large size capacity. At the same time, the measure would allow control point cost to stay down and smaller users to operate using manual assessment methods.
Title 24, Part 6 does not currently regulate the installation of steam traps or require the installation of a strainer with a blow-off valve. The proposed code change represents an addition to Title 24, Part 6 and supplemental documentation where none previously existed.
The proposed measure aims to reduce the overall time a steam trap is left in a failed position, specifically an open (blow-through) position. The primary concern with steam trap failure in an open position is that the failure can go unnoticed for extended periods of time and the associated equipment would continue to operate while wasting energy due to the trap failure. Failure in the closed position wastes minimal energy but impacts overall system performance.
Steam trap effective useful life, quantified by the duration between failures, is improved by using a strainer and blow-off valve upstream of the steam trap. Strainers, and blow-off valves, act to reduce the amount of debris and other contaminants that enter a steam trap, which degrade the device and ultimately lead to otherwise premature failure of the steam trap. Installation of strainers and blow-off valves for all new construction, all additions and all steam trap alterations would increase the duration between steam trap failures.
Additional benefits of the proposed measure may include improved system reliability, reduced overall maintenance, and increased process run time.
Proposed Code Change
The proposed code addition is a mandatory requirement to Section 120.6, Mandatory Requirements for Covered Processes. All new construction, all additions and all steam trap alterations, with connected steam line operating pressure equal to or greater than 30 psig would be subject to the installation of steam trap fault detection and diagnostics per proposed changes to Section 120.6(h)1. All new construction, all additions and all steam trap alterations with connected steam line operating pressure equal to or greater than 30 psig shall have an integral strainer and blow-off valve or the steam trap shall be installed downstream within three feet from the exit of the strainer fitting, per Section 120.6(h)2. “Steam trap alterations” is defined as the replacement of a steam trap. Section 120.6(h)1 and 120.6(h)2 contain a code exception for systems with total combined connected boiler input capacity rating less than 2,000,000 Btu/hr (2.0 MMBtu/hr).
Measure proposals, supporting documents, and other outside references will be made public as they become available.
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The Statewide CASE Team values input from all stakeholders engaged in the Title 24, Part 6 code change process. We encourage the open exchange of code change comments and concerns.
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