# U.S. DOT/PHMSA - Presentation: Briefing Paper on Special Permits to Waive MAOP in New HL Pipe

- **operation:** document
- **citation:** 0900006480e8d3f1
- **title:** U.S. DOT/PHMSA - Presentation: Briefing Paper on Special Permits to Waive MAOP in New HL Pipe
- **source type:** rulemaking
- **agency:** Pipeline and Hazardous Materials Safety Administration
- **status:** current
- **official:** true
- **published on:** Not available
- **effective on:** Not available
- **summary:** The paper: - Describes PHMSA’s past actions and context: recognition of metallurgical and manufacturing improvements, comparison to Canadian standards and ASME committees. - Notes TransCanada Keystone’s November 17, 2006 request to operate at 80% of SMYS (not for high consequence areas, stations, or crossings). - Summarizes PHMSA’s meetings with TransCanada, a January technical meeting covering pipe materials, manufacture, coating, design, construction, testing, operations, leak detection, maintenance, and emergency response, and PHMSA deliberations on overpressure, abnormal operations, and cyclic fatigue. - States PHMSA is reviewing hazardous liquid pipeline accidents caused by abnormal operations (pressure excursions) and notes difficulty in determining if excursions cause premature flaw failure because the effect is accretive. Limitations: all conclusions and descriptions are limited,
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- **source url:** https://downloads.regulations.gov/PHMSA-RSPA-1998-4470-0229/attachment_1.pdf
**body:**

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Briefing Paper February 12, 2007
Consideration of Special Permit to Waive the Maximum Allowable
Operating Pressure in New Hazardous Liquids Pipelines
Advisory Committee Action: Briefing
Project Contacts: Joy Kadnar and Alan Mayberry
Past PHMSA action:
PHMSA continues to seek ways to improve the safety and efficiency of the nation’s
energy infrastructure and in doing so recognizes that improvements in metallurgical
properties, pipeline manufacture, and life cycle management practices have improved the
safety performance of these facilities. The Canadian standards and the National Energy
Board allow hazardous liquid pipelines to operate at 80% of SMYS. The ASME B31.4
committee, unlike the counterpart ASME B31.8 (gas) committee, has not made changes
to allow for higher operating stress levels.
On November 17, 2006 TransCanada Keystone Pipeline, LP requested PHMSA to
consider a waiver to allow them to operate at 80% of the specified minimum yield
strength (SMYS) as opposed to 72% of SMYS, the current regulatory maximum stress
level. The Keystone Pipeline originates at an oil sands supply hub near Hardisty,
Alberta, and extends 1,845 miles to Patoka, Illinois. The US portion includes 1,023 miles
of 36- inch, 55 miles of 24- inch and in the future may include a 291–mile long extension
to Cushing, Oklahoma. TransCanada is not requesting a waiver for portions of the
proposed pipeline operating in high consequence areas, stations and crossings of roads,
railroads and navigable waterways.
PHMSA met three times with TransCanada since last October to discuss the project. In
January PHMSA hosted a technical meeting with TransCanada’s engineering staff to
discuss all known technical issues related to pipe skelp, manufacture, coating, design,
construction, testing, operations inclusive of leak detection, maintenance, and emergency
response. PHMSA debated at length about pressure excursions and abnormal operations.
We wanted to understand why the higher overpressure allowance is reasonable and would
not exacerbate cyclic fatigue. Alternatively, we discussed if it would be reasonable to
impose a lower limit. In researching overpressure and cyclic fatigue issue, PHMSA is
also reviewing hazardous liquids pipeline accident caused by abnormal operations,
specifically pressure excursions. However, because the affect of excursions on flaws is
accretive, it may be very difficult to positively determine if pressure excursions caused
flaws to fail prematurely.
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