Facility Yard Piping Condition Assessment

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By Clinton McAdams

INTRODUCTION

Facilities face an out of sight issue, the condition of their buried yard piping. Much of process piping may remain in service continuously without interruption since installation. Adding to this issue is trying to cost effectively implement needed improvements. In response to these challenges, risk analysis using indirect and direct condition data can prioritize piping for implementing appropriate management actions. In California alone, there are over 1,100 wastewater treatment plants (WWTP) and over 699 potable water treatment plants (WTP). This article presents an example use case for the many facilities in the nation to consider when developing and implementing a multi-year project to repair, rehabilitate, or replace piping, or portions of piping, which are highest priority based upon criticality and/or observed physical condition.

RISK-BASED PRIORITIZATION

Yard piping can include process pipes that carry gas, liquids, sludge, air, steam, and other process streams to and from the various treatment areas. Piping may range up to 144-inch diameter and be comprised of many materials such as reinforced concrete pipe, ductile iron pipe, or welded steel pipe. A risk-based framework can be developed for the specific facility to prioritize condition assessments along with guidelines for conducting condition assessments of various pipe materials and sizes. A condition assessment plan can then be developed that provides a prioritized list of critical piping for inspection, inspection protocol recommendations based on the selected piping attributes, and opinions of remaining useful life to determine when to perform inspections.

Prioritization and other planning efforts can use compiled historical data, such as geographic information system (GIS) layers, computerized maintenance management system (CMMS) exports, historical photos, past reports or studies, and record drawings. Properly managed data can allow results to be presented in a way for future reference. Data managed within a central data repository such as the GIS or CMMS can help lead to better data access for all users and better future data trending like asset deterioration rates.

Weighted risk factors can be used to determine the likelihood of failure (LOF) and consequence of failure (COF) for yard piping. Depending upon identified pipe risk, inspection protocols and desired levels of inspection detail can be determined. A risk analysis framework can define and evaluate the various mechanisms influencing piping risk of failure, allowing each pipe to be compared in an objective way to highlight areas to focus condition assessments. Example risk factors are shown in Table 1, broken down by risk category. Based on the LOF and COF scores, risk categories can be established, such as the examples listed below from the International Infrastructure Management Manual:

• Like new condition
• Minor defects only
• Moderate deterioration
• Significant deterioration
• Virtually unserviceable

CONDITION ASSESSMENT PLANNING & EXECUTION

Where condition assessment is needed, such work can have two objectives: (1) to determine when improvements or other management decisions need to be implemented, and (2) to determine what types of improvements or management decisions need to be implemented. The ability to achieve both objectives depends on data resolution, such as if indirect or direct condition data are available. Indirect data only infers piping condition and may not provide sufficient information for detailed rehabilitation or replacement planning and design, but can support prioritization of buried piping for actions such as where to collect direct condition data or where to implement rehabilitation or replacement depending on the appropriate piping risk category and supporting data. Direct condition data verifies existing condition and may include high-resolution data for design specifications.

Process piping are generally buried and cannot be taken out of service without disruptions to treatment operations, so it is inherently difficult to assess their condition. Assessments typically involve process shutdown and/or isolation, draining and dewatering, flow bypassing, and potholing or excavation. Pipes can be chosen for inspection during any given year based on their relative risk and planned facility shutdowns, as well as the status of other concurrent facility projects. Considering background information, such as pipe materials, sizes, alignment characteristics, and access, a plan can be developed for process shutdowns, where possible, as well as take advantage of opportunities where certain piping or processes are planned to be taken out of service for maintenance or rehabilitation, either directly or indirectly.

Outage or service interruption requests can be prepared for review, allowing solicitation of critical feedback to successfully execute the inspection. Requests can have details regarding the shutdown purpose, work areas, roles and responsibilities, safety procedures, schedule, required access, and approach for conducting the work. Work plans can be developed to collect the highest resolution data while executing field work in the safest manner possible and with the least impact to operations. It is critical that all facility stakeholders are involved early and often throughout the planning process to communicate the shutdown, operating scenarios, and access requirements. This can help leverage planned shutdowns for repair and maintenance activities and already installed temporary bypass piping to effectively execute onsite activities and utilize facility resources. Overall, it is important to remember the planning process may be iterative so the best opportunity to obtain the highest resolution data can be achieved.

Figure 3 shows example methods to assess buried yard piping. From a programmatic standpoint, attempts can be made to capture consistent data per pipe type. For piping greater than or equal to 36-inch diameter, methods like confined space entry inspection can allow a thorough visual inspection to be performed along with the ability to obtain complementary data such as non-destructive testing and sampling for laboratory testing. While methods like physical entry can provide comprehensive data, major considerations for personnel safety and operational constraints need to be considered. Where piping cannot be taken out of service or dewatered, various multi-sensor inspection (MSI) platforms are available depending on the process stream type. For piping less than 24-inch diameter, options are more limited. Closed-circuit television (CCTV) inspection and potholing with non-destructive testing can be used to obtain condition data on smaller pipes.

FOOD FOR THOUGHT

Besides the initial items discussed, listed below are various considerations for those at various stages of a yard piping management program:

• Preparation is Key: Comprehensive plans identifying priorities and methods with well-documented reasons can limit costs during field activities. Due to the latest market conditions, emergency and unforeseen conditions can cost substantially more to address than 5 years ago.
• Be Flexible: Certain activities may not proceed as initially planned. Whether it is fewer contractor bids than expected, working around other active facility projects, or discovering undocumented utilities, remember to remain calm and think creatively.
• Take Photos: Witness field activities and document observations with photos. A picture is worth a thousand words when showing someone else how a pipe was accessed, assessed, rehabilitated, or replaced.
• Organize Data: Master data repositories can mitigate internal data silos. Allowing data access for all appropriate users can support regular asset data updates and recording institutional knowledge. If documented asset history is available, this information can be used to update lifecycle projections and optimize maintenance programs.
• Make Data-Back Decisions: Defining risk criteria identifies what condition data to collect in the future and supports development of prioritized capital and operation and maintenance programs. An initial risk model based on available records can successfully focus resources to collect field data to calibrate the risk model and determine deterioration rates to consider when to prioritize recommendations. Combining multiple data sources may be needed to identify condition trends and root causes of deterioration or damage. Understanding budget costs for various management actions (e.g., replacement, rehabilitation, monitor and inspect, no action) can help inform which is the appropriate choice depending on the piping’s associated risk.
• Be Proactive: Programmatic inspections can identify and mitigate high-risk areas from becoming future emergency responses and service disruptions. Forming a condition baseline and management program can improve system reliability and reduce current and future operation, maintenance, and replacement costs over the yard piping lifecycles.

REFERENCES

AACEI (American Association of Cost Engineering International). (2016). Cost Estimate Classification Matrix, AACEI Recommended Practice No. 18R-97. Christensen, Peter, et al. AACEI, Morgantown, WV.

AWWA (American Water Works Association). (2017) Buried No Longer: Confronting America’s Water Infrastructure Challenge. AWWA, Denver, CO.

AWWA (American Water Works Association). (2019). Condition Assessment of Water Mains. AWWA Manual M77. AWWA, Denver, CO.

AWWA (American Water Works Association). (2017) Leading Business Practices in Asset Management Case Study Report. AWWA, Denver, CO.

California Department of Transportation (Caltrans). (2021). Corrosion Guidelines, Version 3.2. Caltrans,

Jones, D. (1996). Principles and Prevention of Corrosion. Second edition. Pearson. London, UK.

Institute of Public Works Engineering Australasia (IPWEA). (2024). International Infrastructure Management Manual (IIMM). 6th Edition. IPWEA. North Sydney, New South Wales, Australia.

NASSCO (National Association of Sewer Service Companies). (2016) Pipeline Assessment and Certification Program (PACP). Version 7.0.2. NASSCO, Frederick, MD.

PCA (Portland Cement Association). (2002). Concrete Information: Types and Causes of Concrete Deterioration. PCA. Skokie, IL.

Roberge, P. (2006). Corrosion Basics: An Introduction. Second edition. National Association of Corrosion Engineers International. Houston, TX.