Progress: Not Addressed
DOT Relevance: 192.551 192.557
Under Subpart K of 49 CFR 192, the minimum requirements for increasing maximum allowable operating pressure for pipelines are prescribed.
Todays hydrogen pipelines operate at stress levels generally between 30% and 40% of SMYS. To increase pipeline capacity, increased pressures may be required. Increased allowable stress levels can, in part, lead to cost-effective designs at higher pressures.
ASME B31.12 will use only location class 3 and 4 for pipeline design. This will limit the percentage SMYS utilized in design or uprating. The new code will provide location class limits and incorporate design factors to maintain design conservatism until actual research data on material properties is available. The design factors will be used to restrict pipe stresses as the pressure increases and/or the tensile strength of the pipe material is increased or both.
Research needs to be performed to produce research data on material properties so that accurate class limits can be set. Standards and procedures for the uprating of hydrogen pipe should be established and incorporated by reference into the federal code.