Urban gas pipeline networks, as the core of urban energy infrastructure, undertake the continuous gas supply task from gate stations to end users. Most pipelines are buried underground and face long-term risks such as soil corrosion, third-party construction damage, overpressure impact, and fatigue crack propagation. Once a leak occurs, it can cause economic losses at best, or lead to fire, explosion, or poisoning accidents at worst. The concept of "intelligent oil and gas pipeline network" proposed at the 2019 China Intelligent Pipeline Conference has become an industry consensus: achieving visualization, quantification, and predictive maintenance throughout the full lifecycle of pipelines through IoT, big data, digital twins, and other technologies.

In this system, pressure data is the most direct and reliable indicator for judging pipeline integrity, identifying leaks, and assessing operating status. The Nexisense WPAK63 series isolated diaphragm pressure sensor, with high-precision diffused silicon chip as the core and full 316L stainless steel isolated diaphragm packaging, provides long-term stable pressure measurement capability with strong media compatibility, and has been widely applied in urban gas pipeline network SCADA systems, gate stations/regulating stations, network zoning metering, and leak localization projects.

Typical Pressure Monitoring Application Scenarios in Smart Gas Pipeline Networks

Gate stations and regulating stations are core nodes for pipeline network pressure regulation. Inlet high pressure, post-regulation medium/low pressure, and differential pressure before/after stabilizers directly affect downstream gas supply stability. Nexisense sensors are deployed before and after regulators and at key nodes, achieving continuous acquisition with 0.1% FS accuracy, supporting bidirectional overpressure/low-pressure alarms and linkage to shut-off valves.

Buried pipeline network zoning pressure monitoring forms a pressure gradient field by deploying pressure monitoring points at zoning valve wells and intersections. When a leak occurs, pressure wave propagation causes a sudden drop in downstream node pressure and abnormal rise in upstream node pressure. The system can perform leak localization combined with flow data, with localization accuracy reaching the hundred-meter level.

Regulator box and end-user terminal pressure monitoring directly relate to the gas supply stability for residential communities and commercial users. Nexisense low-power modules support NB-IoT/LoRa remote transmission, achieving real-time alerting for terminal pressure anomalies (e.g., below 1.5 kPa or above regulator set value).

Long-term pressure trend data combined with GIS pipeline network models can build a digital twin of the pipeline for fatigue analysis, remaining life prediction, and risk grading management.

Sensor Selection Guide and System Integration Considerations

Key selection parameters:

• Range: -100kPa～0～10kPa…100MPa (gauge/absolute/sealed gauge optional)

• Accuracy grade: 0.1% FS / 0.25% FS / 0.5% FS

• Output signal: 4-20mA (two-wire), 0-5V, RS485 Modbus RTU, HART (optional)

• Medium temperature: -40～+85℃ (standard) / -40～+150℃ (high-temperature type)

• Overload capability: 150% FS (standard) / 200-300% FS (customized)

• Protection grade: IP67 / IP68 (full-welded structure optional)

• Explosion-proof certification: Ex ia IIC T4 Ga / Ex d IIC T6 Gb

Integration considerations:

• Installation position: prioritize straight pipe sections, avoid turbulence interference at elbows and reducers; recommend upstream 10D and downstream 5D straight pipe sections.

• Electrical connection: 4-20mA signals recommend shielded twisted pair with good grounding to prevent electromagnetic interference; RS485 bus uses daisy-chain topology with 120Ω terminating resistors at both ends.

• Temperature compensation: sensor has built-in full-temperature range compensation circuit, but in extreme environments, recommend external ambient temperature sensor for secondary correction.

• Zero and span calibration: perform zero/full-scale calibration with standard pressure source before commissioning; recommend on-site verification every 6-12 months.

• Data acquisition and transmission: supports Modbus RTU (baud rate 9600/19200 bps), HART 7 protocol, seamless docking with mainstream PLCs (such as Siemens S7, Schneider M340, Honeywell), RTUs, and edge gateways.

• Redundancy design: recommend 1+1 redundancy configuration for high-risk nodes, with automatic fault switching and alarming.

The Nexisense WPAK63 series sensors have passed GB3836 explosion-proof certification and multiple EMC tests, compatible with most gas SCADA/pipeline network monitoring platforms.

Project Application Cases

In a smart transformation project for a southern coastal city's gas pipeline network, covering approximately 1200 km of medium- and low-pressure pipelines, more than 1800 Nexisense pressure monitoring points were deployed. The system integrates Modbus RTU and NB-IoT dual-channel transmission, achieving full-network real-time pressure acquisition and zoned leak localization. After commissioning, average leak discovery time was reduced from hours to within 15 minutes, and annual unplanned gas outage events decreased by 67%.

In a digital upgrade of regulating stations in a northern provincial capital city, all 46 regulating stations replaced with Nexisense isolated diaphragm pressure transmitters, supporting HART protocol and seamless integration with the existing Honeywell Experion system. Achieved trend analysis of differential pressure before/after regulators, automatic anomaly diagnosis, and remote parameter tuning, improving regulation accuracy to ±1.5% and reducing equipment failure rate by approximately 40%.

In zoned monitoring of a Yangtze River Delta industrial park gas pipeline network, targeting high gas consumption characteristics of chemical users in the park, Nexisense high-overload sensors were deployed to achieve synchronous monitoring of user-side and pipeline-side pressure. The system successfully identified multiple small-flow leak events through combined pressure-flow analysis, avoiding potential major accidents.

Nexisense OEM/Customization and Bulk Supply Advantages

• Core customization: supports special ranges, non-standard interfaces (M20×1.5, G1/4, NPT1/2, etc.), wide temperature compensation (-40～+150℃), full-welded structure, strong impact resistance (100g) versions.

• Output protocol extension: beyond standard 4-20mA, customizable RS485+4-20mA dual output, LoRa/NB-IoT wireless modules.

• Stable bulk supply: monthly capacity over 200,000 units, autonomous control of 316L isolated diaphragm and diffused silicon chip supply chain, lead time 6-8 weeks.

• Technical support: provides complete characteristic curves, combined temperature-pressure error reports, EMC test reports, SIL2/3 functional safety assessment data package.

• Long-term cooperation assurance: 3-5 year core spare parts inventory commitment, EOL notification 12 months in advance, providing smooth replacement solutions.

Suitable for standardized procurement and deep customization needs of gas meter manufacturers, SCADA system integrators, pipeline network operation and maintenance companies, and EPC general contractors.

Frequently Asked Questions (FAQ)

1. What is the main difference between isolated diaphragm pressure sensors and ordinary diffused silicon sensors in gas media?
      The isolated diaphragm completely physically isolates the sensitive chip from the medium, preventing corrosive components such as hydrogen sulfide and ammonia from directly contacting the chip, significantly improving long-term stability and service life.

2. How to distinguish pressure anomalies caused by pipeline leaks from normal fluctuations?
      Use dual criteria of pressure change rate (dP/dt) + absolute value; typical setting dP/dt > -5 kPa/min and below the set lower limit simultaneously triggers alarm, combined with adjacent node data for correlation analysis.

3. How to ensure signal integrity in long-distance RS485 bus deployment?
      Use shielded twisted pair, each segment not exceeding 1200 m, add 120Ω terminating resistors at both ends, reasonable segmented power supply, and use repeaters or optical isolators.

4. How is sensor zero drift controlled within long-term operation requirements of gas pipeline networks?
      WPAK63 series adopts full-temperature range laser compensation + aging screening process, typical annual drift <±0.1% FS; recommend on-site zero verification every 6 months.

5. What are the advantages of HART protocol compared to Modbus RTU when integrating with SCADA systems?
      HART supports bidirectional digital communication, online reading of diagnostic information, remote setting of range/damping without interrupting 4-20mA analog signal, suitable for retrofitting existing analog loops.

6. What parameters should be paid special attention to when selecting sensors for high-pressure natural gas pipelines (>4 MPa)?
      Prioritize overload capacity ≥300% FS, transient impact resistance type, interfaces using high-pressure tapered pipe threads or flange connections to ensure sealing reliability.

7. How to avoid additional errors caused by sensor installation in regulating station differential pressure monitoring?
      Use equal-length impulse lines, install at the same level, add condensers or heat tracing to eliminate liquid column difference and temperature gradient effects.

8. How does Nexisense ensure consistency of explosion-proof certification during bulk procurement?
      Each batch provides copies of explosion-proof certificates and third-party type test reports, core batch numbers traceable, supporting SIL functional safety assessment data.

9. How is sensor temperature performance guaranteed in low-temperature environments (below -30℃)?
      Provides wide-temperature compensation version (-40～+85℃), built-in PT1000 temperature sensor, enabling secondary temperature compensation with zero temperature drift <±0.015% FS/℃.

10. What core technical indicators must the pressure monitoring system meet during project acceptance?
       Accuracy ≤±0.25% FS, response time ≤200 ms, annual stability ≤±0.1% FS, MTBF ≥80000 h, compliant with GB 50028 "Code for Design of Town Gas" and CJ/T 448 "Technical Requirements for Gas Pipeline Leak Monitoring Systems".

Conclusion

The core of smart gas pipeline network construction lies in "measurable, visible, controllable, and predictable". Pressure, as the most sensitive physical quantity of pipeline operating status, its high-reliability and real-time monitoring directly determines the timeliness and accuracy of leak early warning. Nexisense, with high-precision diffused silicon isolated diaphragm technology as the core, provides engineered solutions from core to complete transmitter modules, helping gas enterprises build data-driven safety management systems and achieve the fundamental shift from passive emergency repair to active prevention.

In the dual context of the "dual carbon" goal and urban resilience enhancement, selecting a pressure sensing partner with long-term stability, system compatibility, and supply chain assurance will significantly reduce pipeline network operation and maintenance costs, improve inherent safety levels, and provide a solid data foundation for digital twins and predictive maintenance.

If gas pipeline network operation units, system integrators, or equipment manufacturers need sensor selection evaluation, prototype testing, or bulk collaboration scheme discussions for specific pipeline network scale, pressure rating, or communication protocol, welcome to contact the Nexisense technical team to jointly formulate the most suitable deployment strategy and long-term support plan.