Overview
A midstream company constructed a cryogenic processing plant fed by a gathering system with two main wet-gas headers. The first wet-gas header was a 20-inch line spanning approximately 25 miles southwest of the plant, while the second wet-gas header was a 24-inch line spanning approximately 30 miles to the northeast into production fields in Ohio and Pennsylvania.
When initial production in the formations southwest of the plant indicated the presence of dry-gas with no hydrocarbon separation required, that 25 mile pipeline was rendered useless, because dry-gas need not be sent to the processing plant. Rather than abandoning the existing wet-gas pipeline, the owner wanted to explore converting it to a Y-Grade Natural Gas Liquids (NGL) pipeline, that would replace a 12-inch NGL output pipeline that was planned to parallel the existing 20-inch pipeline. We were contracted to conduct a study to determine what modifications were required to convert the existing wet-gas pipeline to Y-Grade NGL service within compliance of federal codes.
Solution Details |
| Since pipelines transporting gas are governed by DOT 49 CFR Part 192, and pipelines transporting liquids are governed by DOT 49 CFR Part 195, the first step was to complete a review of each code and identify design/construction requirements set forth by Part 195 that may have not been met by design requirements set forth by Part 192. Project documentation was then reviewed – including design documentation, pipeline/facility as-built drawings, and pressure test records – to determine action required to bring the pipeline into compliance with Part 195. Identified action items included: modification to existing mainline valve settings to accommodate liquid service, implementation of a leak detection system, PIG trap modifications, addition of thermal expansion relief, and identification of “Unusually Sensitive Areas” along the pipeline route. We also prepared a hydraulic flow analysis to determine the pressure drop along the pipeline and confirm that downstream pressure requirements would be met. The client was able to successfully convert the pipeline to NGL service, while enjoying the cost differential savings between converting the existing wet-gas pipeline, as opposed to new construction. | deliverables - Pipeline conversion of service from natural gas to natural gas liquids
- Code comparison between DOT 49 CFR Part 192 & Part 195
- Review of design and construction documentation
- Identification of action items required for service conversion
- Hydraulic flow analysis
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