Overcoming the challenge of obsolete pressure transmitters in aging nuclear power plants
Curtiss-Wright’s strength in nuclear qualified pressure and temperature products is supported by its recent acquisition of Weed Instrument Company, Inc., one of the original specialists in that field. A great example of our organization helping customers overcome the challenge of aging and obsolescence is our DTC3™ pressure transmitter, which was designed as a drop-in replacement for the almost ubiquitous but now discontinued Rosemount™ 1151.
America’s nuclear plant obsolescence challenge
The U.S. has the largest fleet of nuclear plants inthe world. With most plants built in the 1960s and 1970s, the industry is experiencing a growing obsolescence problem, including with installed pressure transmitters.
Pressure transmitters are critical to the operation of nuclear plants because they provide pressure,level and flow measurements for a variety of applications in the steam plant, turbine island and balance of plant areas. A nuclear power plant typically needs 400 to 600 precision pressure and differential transmitters to function properly.
The Rosemount 1151 pressure transmitter madeits debut in 1969. At that time, the Rosemount pressure transmitter offered an unprecedented degree of stability, reliability, and accuracy and became a ubiquitous replacement for older pneumatic and electric transmitters. However, after 40 years in manufacture, the Rosemount 1151 was discontinued. Securing a supply of replacements subsequently became increasingly problematic.
Analog pressure transmitters remain an effective choice
Based on extensive industry experience, we recognize that operators need a cost-effective obsolescence solution that reduces station risk and vulnerabilities associated with equipment reliability, while minimizing implementation and servicing hassle. Analog transmitters remain an effective technology because they fulfill functional requirements, are simple to use and have proven to be very reliable. With that being the case, operators have three options:
Continue to refurbish aging 1151 transmitters
Select a premium nuclear-qualified Class 1E analog pressure transmitter for non-safety or Risk 3 applications
Find an equivalent new analog pressure transmitter
Many plant engineers continue attempting to replace discontinued Rosemount transmitters, despite significant sourcing challenges.
To stay with analog electronics, some operators have invested in premium nuclear grade transmitters, each of which can cost tens of thousands of dollars, even for non-safety applications. In many cases, the total cost of the engineering change can outweigh the procurement cost of the basic components.
Selecting an equivalent new analog pressure transmitter can be a more effective option than attempting to find products that are no longer made or changing up to a costly premium nuclear-qualified analog transmitter.
Selecting a new analog pressure transmitter
Operators needing to replace aging pressure transmitters are under pressure to control costs, improve performance and face an unavoidable requirement to replace major systems to extend plant life. Finding the right replacement analog pressure transmitter has a role in addressing each of these issues so operators must identify:
Functional characteristics of the obsolete transmitter, including environmental, regulatory and quality requirements
Operating experiences with the proposed new transmitter in similar plant environments
A supplier with industry experience, a solid reputation, and a strong supply chain
Competitive total lifetime cost of the transmitter
Curtiss-Wright’s DTC3 pressure transmitter
We saw the need to address the significant pain point of obsolete pressure transmitters in the nuclear industry. Through collaborations with major utilities, user groups and industry experts, we designed a direct replacement for the Rosemount 1151, an analog pressure transmitter that brings the technology into the modern age and features a universal mounting bracket that is compatible with Rosemount 1150 series brackets.
With its precise controls and reliability, our DTC3 is an excellent option for deployment within nuclear plants. It has a true analog design with no microprocessors, firmware or required software and was developed to offer differential, gauge and absolute pressure measurement.
Key features of the DTC3
Easier than switching to smart transmitters
Non-interacting zero and span
Coarse and fine, non-interacting, span and zero adjustments
Local test points for field adjustability
Adjustable damping
Operating regions: 4-20 ma: 12-45 Volts DC (0Ω-1333 Ω); 10-50 ma: 30-85 Volts DC (0 Ω-1100 Ω)
Modular architecture with common components
Universal mounting bracket
The DTC3 is not complicated to calibrate since it does not have zero/span interaction, which occurs when the zero pressure output (4mA) changes when the span is adjusted. The DTC3 has two simple calibration steps compared to six steps for the 1151, saving time in the field and on the bench.
We’re ready to provide stellar technical support to support your plant while transitioning to the DTC3 pressure transmitters, providing onsite and remote assistance with calibration, environmental condition advice, equivalency analysis and more.
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