Leak Detection on Short Lines
Find out how Vanmok Leak Detection helped a major USA pipeline operating company achieve regulatory compliance with the new PHMSA final rule for rupture detection on Short Lines
A major USA pipeline operating company approached Vanmok for a leak detection solution on their Short Lines (Type A Gathering Pipelines). As an operating expense mandated by regulatory requirements, the customer sought a solution that would offer the highest level of detection sensitivity and reliability while minimizing the total installed cost. Vanmok Leak detection technology is significantly more cost effective than other methods, designed specifically for lines with poor telemetry and is partially independent of customer’s IT infrastructure.
The Pipeline and Hazardous Materials Safety Administration (PHMSA) has announced a new final rule (49 CFR 192 49 CFR 195) that took effect on October 5, 2022. The rule includes several highlights specific to leak detection, such as the application to most Type A gas gathering, gas transmission, and hazardous liquid pipelines with diameters of 6 inches or greater. A small subset of rural gathering pipelines that cross bodies of water greater than 100 feet wide are also included.
Under the new rule, a rupture is defined as an “unanticipated or unplanned flow rate change of 10 percent or greater or a pressure loss of 10 percent or greater, occurring within a time interval of 15 minutes or less.” Relevant requirements include leveraging upstream/downstream pressure monitoring and effective leak detection systems, establishing written procedures for identifying and responding to a rupture, and responding to an identified rupture by closing Remote Mainline Valves (RMVs) to isolate the segment within 30 minutes.
Gathering pipelines that connect terminals and processing facilities typically lack proper instrumentation such as SCADA and flow meters. Typically, Real-Time Transient Model (RTTM) based leak detection requires the use of flow meters and pressure transmitters. Due to the cost of the flowmeters themselves, piping modifications, calibration and annual maintenance required, the total installed cost of the solution can be excessive. Additionally, obtaining SCADA/telemetry communication at remote sites to obtain process signals can also drive project costs higher.
Gathering pipelines are large in numbers and are typically spread across operating areas of company. Due to short length and large numbers, it is very important for the pipeline company to deploy a technology that is cost effective while achieving regulatory compliance.
Additional challenges include the following:
- Bi-directional flow
- Multiple batches
- Low operating pressure – just above atmospheric pressure
- Static operating conditions majority of time
Vanmok LD Cloud is cost effective and autonomous solution for leak detection on Short Lines that relies only on pressure data. Vanmok Leak Detection Software (Vanmok LD™ Cloud) can detect leaks up to 1 m³/hr or 3% of the delivery flow rate (whichever is higher) from dynamic conditions (such as leaks from pinholes) to ruptures. In order to achieve this performance, Vanmok LD needs a high sampling rate in the order of 50-100 milliseconds.
Vanmok Gateways are connected to pressure transmitters at each end of the pipeline. This gateway is embedded with cloud-based technology, which scans data from the pressure sensors at a high sampling rate (50 ms/sample). The data is communicated via cellular modem, which routes the data to Vanmok LD Cloud for leak detection analysis. In an event of a leak, the system automatically sends alarms to either smart phones or a computer. Another device, Vanmok PLC connect+, can port alarms to customer control systems by providing a dry contact via cellular network. This solution does not require IT infrastructure and therefore relieves the pipeline company from cyber security threats.
Vanmok LD® works under all operating conditions including process upsets such as unsteady transient conditions, shut-in, start up and shut down of pipeline while achieving the targeted sensitivity and avoiding false alarms as per API 1130 performance metrics for leak detection.
How is compliance achieved and what does a first project look like?
A customer kickstarted the project with a pilot on a chosen Short Line network representative of their system. Table 1 shows details for the short lines chosen for pilot project.
|Operating Range (psig)
|0 – 500
|0 – 500
|0 – 500
|0 – 500
Figure 1. Layout of short lines network.
Design, Construction, and Commissioning
Vanmok gateways are fitted with cell technology, up to 3 analog input channels and can offer either battery backed up solar power or local 120VAC UPS options.
In this example, design inputs from the customer included pressure transmitter channel assignments, site powering options, cell service capability for the Vanmok Gateways. From this, Vanmok provided case one solar powered unit at the East property and one each 120VAC option at the Main and North properties. The customer was responsible procurement of the pressure transmitters and site construction – Vanmok took care of the rest.
When energized, the customer worked with Vanmok to prove site to cloud communication and verify the system was operating as intended.
Vanmok machine learning requires 4 weeks of normal and upset pipeline conditions to ‘learn’ the system. This is intended to tune Vanmok’s proprietary algorithms so it can differentiate between typical process upsets such as transients and real leak conditions. During this time, the customer receives no alarm and it is assumed leaks have not taken place.
After the tuning period, the system is rolled out to the customer and the pipeline is protected by Vanmok technology. After rolling out the system, it continuously learns pipeline operating conditions and automatically re-tunes the leak detection model on weekly basis. False positive alarms occur occasionally during this phase if there is an operating condition that was not experienced during the tuning period. Customers receive alarms that are investigated and if deemed invalid, Vanmok tunes the algorithm so future false positive alarms can be eliminated.
Once rolled out, Vanmok provides 24hr real-time live monitoring of the system. In this example, the customer preferred dry alarm contacts to their control system for leak detection and system health and a Vanmok PLC Connect+ gateway was installed as described above.
Once the gateways are energized, it takes six to eight weeks to complete system roll out. Due to the scalability of the technology, the pipelines can be rolled out in a mass scale of 100 or more segments within a three-month period.
Site Acceptance Test
Due to the impact and severity of leak events, Vanmok recommends a fully functional simulation of a leak event to prove detection sensitivity. In this case, the customer elected to simulate a leak by capturing process fluid in tanks over a period of time. During this series of simulated tests, Vanmok exceeded the PHMSA requirement and detected leaks as little as 5% of the nominal flowrate within a 15-minute period. Within a year of deployment there has only been one false positive alarm reported.
Case Study Summary
API-1130 (RP) – Meets API 1130 performance metrics:
Sensitivity – Detected 5% of the nominal flowrate within 15 minutes
Reliability – Customer has received once false alarm within a year of rollout
Location Accuracy – due to short length of pipeline, the precise location of the leak was not requested
Robustness – The Vanmok system-maintained reliability and sensitivity during abnormal and degraded operating conditions.
Value to Customer
- Meets API-1130 performance metrics and PHMSA compliant
- No flowmeters or piping modifications required
- Autonomous and real-time leak detection
- Low material and construction costs
- Small on-site footprint
- Independent of SCADA and IT infrastructure
- Works where utility power is unavailable and also at off-grid locations
- Fast implementation – scalable technology that can be deployed in mass scale (~100 segments in 3 months)