An Updated Guide for Construction Inspection of Large Diameter Water Pipelines

Construction of large diameter (48-inches and larger) pipelines is a large investment for any water utility. Quality construction is critical to the overall performance, reliability, and service life of any water transmission system. Construction inspection is a critical for quality. Large diameter pipelines offer many challenges to the owner’s team. Large diameter pipelines typically use more complex pipe materials, bedding and backfill materials, appurtenances, corrosion protection requirements, and construction methods than do smaller diameter pipelines. This paper is an update of “A Guide for the Construction Inspection of Large Diameter Pipelines,” from ASCE Pipelines 2009. This paper discusses critical components of large diameter pipeline inspection in the field and at the manufacturer, and includes a convenient checklist for the field inspectors. The paper focuses on the use of large diameter steel and concrete cylinder pipelines for water transmission service. The checklist covers important inspection and testing procedures: right-of-way clearing and restoration; pipe material inspection at the manufacturing plant; pipe handling; pipe material inspection before installation; trenching; pipe-laying; bedding and embedment around the pipe; backfill over the pipeline; external and internal field joints; field welding (weld after backfill, butt straps, and double welds); internal pipe inspection after installation; inspection of appurtenances; patching of coating and lining; installation through tunnels; and hydrostatic, compaction, and non-destructive testing of pipelines.