Frequently Asked Questions

Here you will find a listing of the most frequently asked questions (FAQs) related to the Standards for Increasing the Maximum Allowable Operating Pressure for Gas Transmission Pipelines.
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The alternate MAOP Rule was promulgated by PHMSA to allow certain gas transmission pipelines to operate at higher pressures and pipeline stress levels than regulations previously allowed when designed and operated with more rigorous safety standards. By allowing pipelines to operate at higher pressures and stress levels, greater efficiencies and gas product throughput can be achieved (73 FR 62148).

The rule adds a new section 49 CFR 192.620 in Subpart L - Operations. This new section explains what an operator would have to do to operate at a higher MAOP than formerly allowed by the design requirements. Among the conditions set forth in new 49 CFR 192.620 is the requirement that the pipeline be designed and constructed to more rigorous standards. These additional design and construction standards are set forth in two additional new sections (49 CFR 192.112 and 192.328) located in Subpart C—Pipe Design and Subpart G—General Construction Requirements for Transmission Lines and Mains, respectively. In addition, the rule makes necessary conforming changes to existing sections on incorporation by reference (49 CFR 192.7), change in class location (49 CFR 192.611), and maximum allowable operating pressure (49 CFR 192.619).

The proposed changes were made possible by improvements in pipeline technology and risk controls over the past 25 years. The current standards for calculating MAOP on gas transmission pipelines were adopted in 1970, in the original pipeline safety regulations promulgated under Federal law. Almost all risk controls on gas transmission pipelines have been strengthened in the intervening years, beginning with the introduction of improved manufacturing, metallurgy, testing, and assessment tools and standards. Pipe manufactured and tested to modern standards is far less likely to contain defects that can grow to failure over time than pipe manufactured and installed a generation ago.

Operating stress levels were tied to the pipeline Class location which is a function of the population density near the pipeline. In sparsely populated Class 1 locations, the design factor specified in 49 CFR 192.105 restricts the stress level at which a pipeline can be operated to 72% of the specified minimum yield strength (SMYS) of the steel. The operating pressures in more populated Class 2, Class 3, and Class 4 locations are limited to 60, 50, and 40 percent of SMYS, respectively.

Pipelines in class 1 locations may operate at stress levels up to 80 percent of SMYS when the conditions of the alternative MAOP Rule are met. The rule adds a new section, 49 CFR 192.620, to specify what actions an operator must take in order to elect an alternative MAOP based on higher operating stress levels. The rule applies to both new and existing pipelines. Pipelines in class 2 and 3 areas meeting the requirements in new section 49 CFR 192.620 can also raise their stress levels to 67% SMYS and 55% SMYS. There are no provisions for raising the stress level in a class 4 location higher than the existing 40% SMYS.

Yes. Several types of pipeline segments will not qualify under this rule. These include the following:

• Pipeline segments in densely populated Class 4 locations.
• Pipeline segments of grandfathered pipeline¹ already operating at a higher stress level but not constructed in accordance with modern standards.
• Bare or ineffectively coated pipe.
• Pipelines with wrinkle bends.
• Pipelines experiencing failures indicative of a systemic problem, such as seam flaws, during initial hydrostatic testing.
• Pipe manufactured by certain processes, such as low frequency electric welding process.
• Pipeline segments which cannot accommodate internal inspection devices.

Yes. The committee responsible for development of the B31.8 Code, now under the auspices of the American Society of Mechanical Engineers (ASME), determined pipelines could operate safely at stress levels up to 80 percent of SMYS. ASME updated the design factors in a 1990 addendum to the 1989 edition of the B31.8 Code, and they remain in the current edition.

Yes. 49 CFR 192.620(c)(1) requires an operator to notify PHMSA, and applicable state pipeline safety regulators, when it elects to establish a higher alternative MAOP. This notification must be provided at least 180 days prior to commencing operations at the alternative MAOP. This will provide PHMSA and states sufficient time for appropriate inspection which may include checks of the manufacturing process, visits to the pipeline construction sites, analysis of operating history of existing pipelines, and review of test records, plans, and procedures.

An operator seeking to operate at a higher pressure than allowed by past regulation must certify that a pipeline is built according to rigorous design and construction standards and must agree to operate under stringent operations and maintenance (O&M) standards. 49 CFR 192.620(c)(3) requires the certification to be submitted at least 30 days prior to operation at a higher alternative MAOP. After PHMSA or state pipeline safety authority (when the pipeline is located in a state where PHMSA has an interstate agent agreement, or an intrastate pipeline is regulated by that state) receives an operator’s certification indicating its intention to operate at a higher operating stress level, PHMSA or the state would then follow up with the operator to verify compliance.

Yes. The Rule would allow an operator to qualify both new and existing segments of pipeline for operation at the higher MAOP, provided the operator meets the MAOP Rule conditions for the pipeline segment.

Formerly pipeline operators were allowed to submit Special Permit requests to PHMSA to request approval to operate at pressures greater than allowed by the former regulations. Operators of those pipelines must comply with the final rule in order to operate their pipelines at a higher alternative MAOP. PHMSA will examine special permits that have already been granted, as appropriate, to determine if any modifications are needed.

Yes. The rule adds a new section to Subpart C—Pipe Design in 49 CFR Part 192. The new section, 49 CFR 192.112, prescribes additional design standards required for the steel pipeline to be qualified for operation at an alternative MAOP based on higher stress levels. These include requirements for rigorous steel chemistry and manufacturing practices and standards. Pipelines designed under these standards contain pipe with improved toughness properties to resist damage from outside forces and to control fracture initiation and growth. The considerable attention paid to the quality of seams, coatings, and fittings is intended to prevent flaws leading to pipeline failure. Unlike other design standards, 49 CFR 192.112 applies to a new or existing pipeline only to the extent that an operator elects to operate at a higher alternative MAOP than allowed in current regulations.

Yes. The rule adds a new section to Subpart G—General Construction Requirements for Transmission Lines and Mains. The new section, §192.328, prescribes additional construction requirements, including rigorous quality control (QC) and inspections, as conditions for operation of the steel pipeline at higher stress levels. Unlike other construction standards, § 192.328 would apply to a new or existing pipeline only to the extent that an operator elects to operate at a higher alternative MAOP than allowed in current regulations.

49 CFR 192.620(a) describes how to calculate the alternative MAOP based on the higher operating stress levels. Qualifying segments of pipeline would use higher design factors to calculate the alternative MAOP. For a segment currently in operation this would result in an increase in MAOP. No changes were made in the design factors used for segments within compressor or meter stations or segments underlying certain crossings. PHMSA expects new pipelines operating per the alternative MAOP to have road/railroad crossings, fabrications, headers, mainline valve assemblies, separators, meter stations and compressor stations designed and operated per existing design factors in 49 CFR 192.111.

49 CFR 192.620 (b) describes which segments of new or existing pipeline are qualified for operation at the higher alternative MAOP. The higher alternative MAOP is allowed only in Class 1, 2, and 3 locations. Only steel pipelines meeting the rigorous design and construction requirements of 49 CFR 192.112 and 192.328 and monitored by supervisory data control and acquisition systems qualify. Mechanical couplings in lieu of welding are not allowed and 95 percent of girth welds must have been examined for existing pipelines to operate at alternative MAOP. Class 4 locations are not allowed to operate using a higher alternative MAOP.

49 CFR 192.620 (b) provides for the performance of a root cause analysis to determine if a failure is indicative of a systemic problem and precludes use of a higher alternative MAOP only if a failure is determined to be systematic in nature. Results of the analysis must be reported to regulators (PHMSA Regional Office or applicable state regulatory authorities).

49 CFR 192.620 (c)(4) addresses initial strength testing requirements. In order to establish a higher alternative MAOP, an operator must perform the initial strength testing of a new segment at a pressure at least as great as 125 percent of the MAOP in Class 1 locations and 150 percent in Class 2 and 3 locations. Since an existing pipeline was previously operated at a lower MAOP, it may have been initially tested at a pressure less than these levels. If so, §192.620(c) allows the operator to elect to conduct a new strength test in order to raise the MAOP.

49 CFR 192.620(c)(6) addresses the need for performance of both new construction and future maintenance activities to ensure the integrity of the segment. This section requires operators seeking to operate at the allowable higher operating stress levels to treat construction tasks as if they were covered by subpart N, ‘‘Qualification of Pipeline Personnel.’’ Construction activities would be OQ covered tasks regardless of whether or not they meet the four-part test in 49 CFR 192.801(b)

49 CFR 192.620(d) sets forth ten operating and maintenance requirements that supplement the existing requirements in part 192. These include requirements for an operator to evaluate and address the issues associated with operating at higher pressures. Through its public education program, an operator must inform the public of any risks attributable to higher pressure operations. The additional operating and maintenance requirements address the two main risks the pipelines face, excavation damage and corrosion, through a combination of traditional practices and integrity management. Traditional practices include cathodic protection, control of gas quality, and maintenance of burial depth. Integrity management includes internal inspection on a periodic basis to identify and repair flaws before they can fail.

The alternative MAOP is higher than the upper limit of the required overpressure protection under previous regulations. 49 CFR 192.620(e) increases the overpressure protection limit to 104 percent of the MAOP, which is 83.2 percent of SMYS for a pipeline segment operating at the alternative MAOP in a Class 1 location.

At higher operating stress, the likelihood that a failure could also cause a running fracture is greatly increased, because of the increased energy in the pipeline due to the increased pressure. This leads to the need to have some method of eliminating or arresting running fractures. Newer high strength steels have some properties that will assist in reducing the chances of a fracture running. An operator must demonstrate that the pipeline steel has these properties or must provide for another method of arresting running fractures.

All steel pipe is made from either plates or coils. If these steel plates or coils are of superior quality, then the pipe will also be of superior quality. Assuring quality requires that the mill that made the plate or coil had an inspection and quality control program to limit variation and to improve the quality of its final product – the plate and/or coil. The condition simply requires that operators verify that such a program was in place at the mill.

The alternate MAOP rule allows operators to establish MAOPs higher than previously allowed by 49 CFR Part 192. One of the requirements is to have mill test reports (mechanical and chemical properties) on the steel that went into the pipe that will operate under the higher stress levels allowed by the alternate MAOP rule. This requirement was included because PHMSA needs assurance that the pipe operating at higher stress levels does not to pose a risk to the integrity of the pipeline. To provide this assurance, an operator must have documented proof of the actual yield strength, tensile strength, and chemistry properties of the steel used in the pipe.

To comply with this provision, carbon dioxide must be limited to 3% maximum. Blending is not allowed. If the operator plans to operate above the 3% carbon dioxide limit, the pipeline is not eligible for operation under the alternative MAOP rule. This provision does not depend on whether the transported gas is wet or dry (i.e., maintaining water vapors below 7 lbm per MMSCFD.

The rule is intended to allow a pipeline to operate at an alternative MAOP (up to 80% SMYS) if the operator has a robust program to assure pipe integrity. This includes restricting carbon dioxide, hydrogen sulfide, and free water, and having a program to monitor the gas stream and run cleaning pigs, as required, to address deleterious gas stream constituents.

The advisory bulletin informs pipeline system owners and operators of the potential for high strength line pipe installed in recent pipelines may exhibit inconsistent chemical and mechanical properties. Yield strength and tensile strength properties that do not meet the line pipe specification minimums have been observed. This advisory bulletin pertains to microalloyed high strength line pipe grades, generally Grade X-70 and above. PHMSA has reviewed metallurgical testing results from several recent projects indicating pipe joints produced from plate or coil from the same heat may exhibit variable chemical and mechanical properties by as much as 15% lower than the reported strength values by the pipe manufacturer. The advisory bulletin can be obtained online at the following URL. [http://www.phmsa.dot.gov/pipeline/regs/advisory-bulletin]

PHMSA expects operators of pipelines under the alternate MAOP to perform in-Line Inspections (ILI) that will identify (remove) all threats to the pipeline. The operator should plan to use a high resolution deformation tool in lieu of a geometry tool to address the threat described in the Advisory Bulletin. The deformation tool must include multi-finger sensors and have an accuracy of +/- 1% to identify expanded pipe and dents.

The results of the initial ILI must be integrated with the initial CIS and DCVG/ACVG surveys required in accordance with §192.620(d). The operator should evaluate and repair all anomalies, expanded pipe and dents in accordance with the MAOP Rule prior to increasing the pressure above the 72% SMYS MAOP to the alternative MAOP of 80% SMYS for Class 1 locations.

The results of all deformation and geometry tool run results for expanded pipe and dents should be analyzed and submitted to the PHMSA Regional Director. All pipe exhibiting an indicated diameter greater than 1.00 % (based upon pipe diameter) above the nominal pipe diameter should be noted on the report of potential deformations.

The operator should review with PHMSA Regional Director, the deformation and/or geometry tool reports. This analysis will consider pipe properties and property distributions, hydrostatic test pressures and reported test behavior, and pipe end to center variations. Based on local pressure and expected behavior, any expansion exceeding anticipated expansion by more than 1.50% may be investigated by excavation to determine actual expansion and, if necessary, to verify pipeline special permit segments yield and ultimate tensile strengths, elongation and chemistry. This guideline may be modified by PHMSA if initial verification reviews by PHMSA Regional Director shows negligible integrity risk.

49 CFR 192.620(c)(6) requires “If the performance of a construction task associated with implementing alternative MAOP can affect the integrity of the pipeline segment, treat that task as a “covered task”, notwithstanding the definition in § 192.801(b) and implement the requirements of subpart N as appropriate.”

An operator must have and follow an Operator Qualification (OQ) Program for construction tasks that can affect pipeline integrity. The Construction OQ program must comply with 49 CFR 192.801, must be followed throughout the construction process for the qualification of individuals performing tasks on an alternative MAOP special permit pipeline.

If the performance of a construction task associated with implementing the alternative MAOP, including the performance of construction tasks required by conditions in MAOP Rule or MAOP special permit can affect the integrity of the pipeline segment, the operator must treat that task as a “covered task”, notwithstanding the definition in § 192.801(b), and implement the requirements of Subpart N as appropriate.

A construction quality assurance plan (§ 192.328(a)), to ensure quality standards and controls of the pipeline, must be followed throughout the construction phase with respect to the following: pipe inspection, hauling and stringing, field bending, welding, non-destructive examination of girth welds, applying and testing field applied coating, lowering of the pipeline into the ditch, padding and backfilling, and hydrostatic testing. These tasks can affect the integrity of the pipeline segment and must be treated as covered tasks.

Other tasks that can affect pipeline integrity which must be treated as covered tasks include, but are not limited to, surveying, locating foreign lines, one call notifications, ditching, alternating current (AC) interference mitigation, cathodic protection (CP) system surveys and installation, directional drills, anomaly evaluations and repairs, right of way clean up (including installation of line markers), and quality assurance monitoring.

All construction tasks associated with implementing alternative MAOP must comply with § 192.620(c)(6), regardless of when the task was performed. In cases where previously completed construction tasks do not fully comply with § 192.620(c)(6) such as pipelines constructed prior to the effective date of the rule, operators may apply for a special permit in order to get relief from this requirement.

Part 192 applies to operators of pipelines. This includes design, construction, operational, maintenance, integrity management, operator qualification, and all other requirements. All requirements must be implemented by pipeline operators. Customers of the operator who are not themselves pipeline operators are not obligated to comply with Part 192 and PHMSA has no enforcement authority over them. The operator is directly responsible for compliance with 192.620(d)(5)(ii) as it applies to their pipelines. If the operator relies on equipment owned or operated by another entity to meet regulatory requirements, they are responsible for assuring the equipment is appropriately maintained and correctly operates. Further, the operator must assure that personnel working with or maintaining the equipment meet applicable regulatory requirements such as Operator Qualification and Drug/Alcohol testing criteria. The operator would also be required to maintain mandatory records documenting compliance with all applicable regulations. If separation equipment owned and operated by one of the pipeline operator’s customers failed to perform adequately resulting in contaminants entering the pipeline, PHMSA would consider the operator responsible for the circumstances leading to and resulting from the failure. The operator would be obligated to address the situation with the customer and PHMSA would hold the operator responsible for protecting against corrosion in its pipeline.

In accordance with National Association of Corrosion Engineers (NACE) 0502-2002, Section 3.4.1.3, 100 percent direct examination is an acceptable method and complies with § 192.925. American Society for Testing and Materials (ASME) B31.8S, Section 6.1 also indicates that operators may choose to conduct direct examination of the entire length of the segment being assessed. To address external corrosion and dents, operators must make detailed measurements and/or maps of the metal loss and/or indentation. To address internal corrosion, operators must examine the pipe for internal metal loss by Non-Destructive Evaluation (NDE) methods such as ultrasonic testing (UT). To address stress corrosion cracking (SCC), operators must examine the pipe for SCC by NDE methods such as magnetic particle inspection (MPI). See also § 192.939 as it relates to the maximum intervals for each of the different reassessment methods.

The excerpt of the preamble of the final rule cited in the question merely acknowledges that the pre-existing § 192.309(b) applied to new pipelines under construction and that the pre-existing § 192.933(d) applied to existing operational pipelines. As stated in the initial paragraph of the response “PHMSA recognizes that the repair criteria in this rule are more stringent than those in subpart O. PHMSA considers this appropriate. A pipeline that will operate under alternative MAOP is subject to more stress and has less wall thickness margin to failure than most pipelines operating under subpart O (with the exception of some grandfathered lines).” The repair criteria in § 192.620(d)(11)(ii) are intended to require that dents in existing lines implementing alternative MAOP must be repaired if they meet criteria in either § 192.309(b) [per § 192.620(d)(11)(ii)(A)] or § 192.933(d) [per § 192.620(d)(11)(ii)(B)]. This is intended to assure that existing pipelines that will be operated at stress levels allowed by the alternative MAOP rule are in “like new” condition with respect to dent defects.