Engineering, Design, and Fabrication of Flanges and Reinforced Elbows for an Essential Service Water (ESW) Polyethylene Pipeline

30 years ago, steel pipe was the standard in the ASME code for raw water supply and raw water handling at Nuclear Power Plants. At some power plants, despite best efforts, that steel pipe has suffered intermittent leakage from external and severe MIC internal corrosion. Additionally, internal tuberculation and mineral build-up has severely constricted flow in other pipelines. Advanced, engineering pipe-grade polyethylene pipe has been extruded and used in some nuclear power plants as the effective method to eliminate corrosion and tuberculation of raw water system pipelines. Implementing the change to earth-quake tolerant polyethylene pipelines has resulted in decreased maintenance, increased system reliability, and improved plant longevity. The expectation is that the advanced polyethylene will provide continuous service up to 100 years from initial installation, with a very low statistical probability of any pressure rupture during its service life. Herein discussed is the engineering grade of polyethylene material, its design basis, the conversion of extruded heavy-wall pipe (Picture 1) into fabricated components, and the final production of fully pressure-rated, fabricated pipe fittings with wall thickness of up to 5-inches. Fabrication pictures 1 to 12 are included.Copyright © 2009 by ASME