Understanding the Mega Rule: Accurate Close Interval Surveys

Performance

At Dairyland we know that the scale and scope of the Mega Rule updates continues to present challenges to pipeline operators. This article is the first in a series by our team, designed to provide clarity amid the many new complexities of the Mega Rule. We also present solutions to some of the key challenges to enable informed decision making and compliance.

Background

The Mega Rule builds on and updates existing legislation designed to reinforce a risk management approach to the safety of natural gas transmission pipelines, natural gas distribution pipelines, and hazardous liquid transmission pipelines. Its third and final part became effective in 2023 with a compliance deadline of February 2024.

Part 3 of the Mega Rule builds on its preceding parts that respectively tackle maximum allowable operating pressure (MAOP) and integrity management near high-consequence areas (HCAs), and the extension of federal safety requirements to onshore gas gathering pipelines with large diameters and high operating pressures.

It clarifies integrity management regulations from corrosion control requirements and repair criteria to post extreme weather inspection. It applies to onshore gas pipeline infrastructure spanning both HCA, and non-HCA.

Compliance with the Mega Rule in its entirety is firmly the responsibility of operating companies, the reality of which will vary depending upon the existing systems in place. Rule updates such as these can be challenging and implementing a compliant integrity management program has time and cost implications. However, Dairyland’s expertise and technologies can be put to work to ensure compliance, safety, and competitive edge.

Challenge #1: External Corrosion

To ensure compliance, pipelines must be monitored to determine cathodic protection (CP) Ievels. Definitively proving that a CP system is providing the degree of corrosion protection required is time-consuming and often inaccurate. Field testing has shown that interrupted surveys can sometimes be impacted by combinations of factors, such as pipeline coatings, soil resistivity, and the capacitance of traditional decouplers resulting in excessively electro-negative instant-off values. Nonetheless, where CP readings are below the required level, a close-interval-survey (CIS) is required to be completed. The CIS needs to be completed both upstream and downstream of the reading.

Any deficiencies must be remedied within a rule-stipulated window and following the completion of remedial action, an interrupted CIS must be undertaken again to ensure the pipeline potential readings are acceptable – incurring time and cost implications and increasing risk to personnel.

Solution #1: PCRX, The CIS Solution

The PCRX is the most sophisticated decoupler available globally. A solid-state, maintenance-free device, it is designed to simultaneously provide DC decoupling and AC continuity/grounding when used with CP structures. The PCRX provides typical decoupler functions with the additional benefit of electronically compensating for capacitance effects during interrupted surveys, including CIS. This prevents the device from contributing to errors in potential readings. The PCRX compensates to overcome capacitive effects, ensuring accurate and timely potential measurements. It does this without sacrificing the rugged over-voltage protection, AC mitigation, CP isolation, and safety grounding of Dairyland’s standard decoupling products.

With the Mega Rule impacting approximately 300,000 miles of existing onshore natural gas pipeline, and almost 20,000 miles of planned pipeline in the US, extending the life of these assets and building them in compliance with the regulations will require innovative technology and solutions.

In multi-purpose corridors where pipelines share the Right-of-Way (ROW) with high-voltage power lines, for example, corrosion risk is increased, as is safety risk to personnel. PCRX, however, will provide an effective grounding path that mitigates induced AC, while simultaneously maintaining DC isolation. This is possible because PCRX provides a low impedance to AC and high resistance to DC simultaneously. As a result, CP systems will continue to work efficiently, and pipelines plus personnel will be safe from undesirable AC interference.

With applications for retrofitting and new-build infrastructure, PCRX is proving to be an essential part of the modern CP system on pipelines and other protected structures for accurate CP readings while improving system performance and delivering the required safety protections.

Dairyland is here to help you make decisions on how our solutions can be applied to achieve Mega Rule compliance. Our technical support staff is ready to support you in a variety of ways, and always offer free personal consultations to help customers decide how to apply Dairyland solutions to your system.