管道修复人的圈子

随着我们的基础设施老化，公用事业公司面临越来越大的压力，以最大限度地利用其资源。压力管道状况评估可以帮助资产所有者更好地了解管道何时需要维修、更换或允许安全地继续使用。从筛选技术（如闭路电视、声学泄漏/气袋检测、土壤腐蚀性测试）到直接评估技术（如电磁、导波、磁通泄漏等），有几种可用的压力管道评估技术。了解每种技术的功能和限制的基本原理，以及公用事业公司对其状况评估的具体目标，这一点很重要。如果特定管道过去曾出现过泄漏并且在结构上趋于保持稳定，则对泄漏进行预筛选可能就足够了。如果被评估的管道类型由于壁损失而出现爆裂，则气瓶评估工具可能更合适。衡量管道的“风险”或故障后果和更换成本也有助于确定哪种类型的评估最合适。管道的位置和类型还可以确定哪种技术是实用的。

利用管道段的状况评估技术，以防止出现重大故障或未来故障，可以帮助顾问和公用事业公司做出最佳决策并最大限度地提高资本改善计划预算。公用事业公司应该通过 NASSCO 和 AWWA 的压力管道委员会以及行业活动、技术演示和顾问研讨会/建议对可用技术有很好的了解。管道状况评估完成后，确定需要解决的管道段，并可以根据最合适的非开挖技术开始修复或更换过程。

NASSCO Report – Pressure Pipe Rehab Using Sliplining with FRP

As our infrastructure ages, utilities are under increased pressure to maximize their resources. Pressure pipeline condition assessments can help asset owners better understand when pipes need to be repaired, replaced or allowed to safely remain in service.

There are several available pressure pipe assessment techniques from screening technologies (such as CCTV, acoustic leak/gas pocket detection, soil corrosivity testing) to direct assessment technologies (such as electromagnetic, guided wave, magnetic flux leakage, etc.).

It is important to understand the fundamentals of what each technology’s capabilities and constraints are, as well as the utility’s specific goals for their condition assessment. If a particular pipe has exhibited leaks in the past and tends to hold up structurally, a pre-screening for leaks may be sufficient. If the type of pipe being assessed has exhibited bursts due to wall loss, a cylinder assessment tool may be more appropriate. Weighing a pipeline’s ‘risk’ or consequence of failure and cost of replacement can also help inform which type of assessment is most appropriate. The pipeline’s location and type can also determine which technology is practical (i.e., exposing a pipe for external scans along a highway vs. exposing a pipe in an easement lawn).

Utilizing a condition assessment technology that can narrow down the pipeline segments that must be addressed to prevent eminent or future failures can help consultants and utilities make the best decisions and maximize capital improvement plan budgets. A utility should gain a good understanding of available technologies through NASSCO’s and AWWA’s Pressure Pipe Committees, as well as industry events, technical presentations and consultant workshops/advice.

Once pipeline condition assessment is completed, the pipeline segments which need to be addressed are identified and the process of rehabilitation or replacement can begin based on the most appropriate trenchless technology.

The structural rehabilitation of pressure pipelines (water or wastewater) by segmental sliplining is a common installation method, resulting in a new pipeline replacement, providing improved flow with minimum excavation and substantially less system downtime.

Fiberglass-reinforced, polymer mortar pipes (FRP) are ideally suited for rehabilitation of deteriorating pressure pipelines. Pipes are designed and factory manufactured and tested to meet the required operating pressure including surge conditions of the system. FRP pipes yield high strength, yet thin-walled cross section, allowing for a fully structural finished product with high compressive loads allowing for long (push or pull) installations. Pipe joint design along with short pipes allow for installation around curves. Resilient inner liner and a slim wall permits greatest recovery of flow in rehabilitated pipelines, with hydraulic characteristics virtually unchanged with time.

Case Study:

A rupture of a 102-in. diameter pipe in 1996 raised concerns about the structural integrity of a 9.5-mile-long aqueduct that supplies water to about 600,000 customers. Since that failure, the owner has taken vigilant measures to avoid disaster and embarked on a systematic and comprehensive inspection, repair and risk assessment program. Using historical data, real-time monitoring and inspections performed every three to five years help make informed decisions about the long-term operation and maintenance of this critical pipeline.

Sliplining with FRP offered a solution that allowed for needed repairs but also started to incrementally replace the entire pipeline with a fully structural (replacement) pipe that won’t compromise hydraulics, minimizes disruption and downtime, or impact the Capital Projects Budget. Because work was done in different segments and areas, there were additional challenges. Specially design and installed pipe end seals minimized excavation points, therefore eliminating the need for access at the end of each segment rehabilitated.

The first phase took place in 2016. The existing 78-in. PCCP was sliplined with 10-ft and 20-ft pipe lengths of 69-in. FRP pipe for a total of about 330 ft. The following year, in 2017, the existing 78-in. PCCP was sliplined with 2.5-ft, 5-ft, 10-ft and 20-ft pipe lengths of 69-in. FRP pipe, totaling 1,140 ft. In 2019, it totaled almost 1,800 ft. The existing 102-in. PCCP was sliplined with 5-ft, 10-ft, and 20-ft pipe lengths of 90-in. FRP pipe. The various segment lengths allow the ability to navigate curved sections and provide a continuous installation for full structural integrity.