The construction specifications for the 76-mile Prairie Rose Pipeline, owned by Pecan Pipeline, required a North Dakota registered professional engineer to prepare a hydrostatic testing plan and procedure and then witness and certify the pressure test of the pipeline prior to it being placed into service.
The construction contractor, Venables Construction, Inc. engaged IPS Engineering / EPC to provide this professional engineering service.
The engineering professionals at IPS Engineering / EPC have been involved in the design, planning and execution of numerous pipeline hydrostatic pressure tests. Using this experience, the construction drawings and construction specification requirements were used to prepare a testing plan.
Key elements required by the specifications to be in the hydrostatic test plan included:
- A written test procedure for filling and pressurization of the pipeline test sections, including preparation of pressure-volume plots
- A test section schematic with planned test header locations, volumes and test pressures
- A procedure for determining the volume of any trapped air in the test sections
- Sample calculations to account for pressure change due to a change in the temperature of the test section
After mechanical completion of the pipeline an IPS Engineering / EPC professional engineer was mobilized to the job site, located near Minot, North Dakota to witness the testing of the pipeline.
After arrival on site the engineer used as-built survey information to finalize the test section lengths, the materials in each test section, high and low elevations and the elevation of the test headers. The test section fill volumes and target test pressures were updated using this information prior to conducting the hydrostatic pressure tests.
The deliverables, sealed by the engineer, to document the successful completion of each test section included:
- A Test Letter describing the test section, the actual pressure test events, and a summary of the test section data and pressures
- A pressure-volume plot (stroke plot) for the pressurization of the test section
- The pressure log for the test section
- Calculations for the test section, including pressure-volume data analysis for theoretical squeeze volumes vs. actual volumes, estimation of trapped air and variations in pressure due to temperature change
This documentation, along with other relevant test documents including pressure charts and calibration records were organized into job books on site and presented to the Client prior to the test engineer’s departure.
The Prairie Rose Pipeline hydrostatic pressure test was successfully conducted and documented. The pipeline was placed into service the first quarter of 2010.