NTSB Safety Recommendation P-84-026

NTSB safety recommendation P-84-026.

THE NTSB RECOMMENDS THAT THE RESEARCH AND SPECIAL PROGRAMS ADMINISTRATION: AMEND FEDERAL REGULATIONS GOVERNING PIPELINES THAT TRANSPORT HIGHLY VOLATILE LIQUIDS TO REQUIRE A LEVEL OF SAFETY FOR THE PUBLIC COMPARABLE TO THAT NOW REQUIRED FOR NATURAL GAS PIPELINES. (Supersedes P-72-008, P-73-012, P-79-030, P-80-089, and P-80-090)

Priority: CLASS II

Overall Status: Closed - Unacceptable Action

Issued Date: 1984-06-18

Adopted Date: 1984-05-15

Overall Date Closed: 1998-07-27

Synopsis: ON MARCH 15, 1983, AN 8-INCH-DIAMETER LIQUIFIED PETROLEUM GAS (LPG) PIPELINE OPERATED BY THE MID-AMERICA PIPELINE SYSTEM (MAPCO) WAS DAMAGED BY A ROTATING POWER AUGER BEING USED TO DRILL HOLES IN ROCKY TERRAIN TO PLANT TREES ON LOT 8, SECTION 5, BLOCK 43 OF THE CHAPARRAL ESTATES HOUSING DEVELOPMENT NEAR WEST ODESSA, TEXAS. THE DAMAGED PIPELINE RUPTURED AND WITHIN 3 MINUTES, LPG, WHICH WAS BEING TRANSPORTED AT 1,075 PSIG, ESCAPED, VAPORIZED, AND WAS IGNITED BY AN UNDETERMINED SOURCE. IN THE RESULTANT FIRE, FIVE PERSONS WERE KILLED AND FIVE PERSONS WERE SERIOUSLY INJURED--ONE PERSON DIED 5 DAYS LATER. TWO MOBILE HOMES, A SMALL FRAME HOUSE, AN AUGER TRUCK, TWO CARS, AND A PICKUP TRUCK WERE DESTROYED; 9,375 BARRELS OF LPG WERE BURNED.

Probable Cause: None

Ntsbnumber: DCA83MP015

Report Number: PAR-84-01

Addressee Name: RSPA

Addressee Status: Closed - Unacceptable Action

Addressee Date Closed: 1998-07-27

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 1987-07-20

Communication Type: Recommendation Reiteration

Communication Contents: From the accident report of the Williams Pipe Line Company liquid pipeline rupture and fire in Mounds View, Minnesota on July 8, 1986 (adopted on 7/20/1987): Safety Recommendation P-84-26 is reiterated in this report.

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 1981-06-11

Communication Type: Recommendation Reiteration

Communication Contents: From the pipeline accident report of the liquid propane pipeline rupture and fire of the Texas Eastern Products Pipeline Company pipeline in North Blenheim, New York on March 13, 1990.The Board adopted this report on 6/11/1991. Also, the Safety Board reiterated the following safety recommendations to the Research and Special Programs Administration: P-84-26, P-87-2, and P-87-22.

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 1990-06-19

Communication Type: Recommendation Reiteration

Communication Contents: From the railroad accident report: Derailment of Southern Pacific Transportation Company freight train on May 12, 1989 and subsequent rupture of Calnev petroleum pipeline on May 25, 1989 in San Bernardino, California. The Board adopted this report on 6/19/1990. As a result of its investigation, the Safety Board also reiterated the following safety recommendations: P-84-26, P-87-6, P-87-7, P-87-22, and R-89-50.

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 1997-10-31

Communication Type: Official Correspondence

Communication Contents: NTSB REQUESTED A FOLLOWUP ON THIS DATE 10/31/97.

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 1993-03-08

Communication Type: Official Correspondence

Communication Contents: Safety Recommendation P-84-26 requested the RSPA to amend Federal regulations governing pipelines that transport highly volatile liquids to require a level of safety for the public comparable to that now required for natural gas pipelines. The Safety Board notes no change from the RSPA October 18, 1991, response that it will continue to study the need to amend the regulations to establish more stringent safety standards for hazardous liquid pipelines in populated areas. The Safety Board understands that the RSPA deferred the study pending implementation of the legislative proposals that were enacted into law, P.L. 102-508, which requires comparable action by October 1994. Therefore, Safety Recommendation P-84-26 will remain in an "Open--Acceptable Response" status.

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 1986-08-20

Communication Type: Official Correspondence

Communication Contents: It appears that the Research and Special Programs Administration (RSPA) may have missed the thrust of this recommendation. The Safety Board is recommending that the safety standards for liquid pipelines be equivalent to natural gas pipeline standards. The requirements contained in 49 CFR 192.611 were cited in the analysis of this accident as only one example of how gas pipeline safety regulations are more stringent than those for liquid pipelines, particularly when there is an increase in population density adjacent to such pipelines. Based on our knowledge of the history of the ANSI B31.8 Code, the industry rationale for development of the population-based class location criteria was not solely in response to its concern about ,fracture propagation; it was also in response to industry's overall concern about the increasing populations residing adjacent to its pipelines which initially were located in non-inhabited areas. Class location standards require more than adjustments in the design safety factor; they also require increased safety for the exposed population by imposing more stringent operating and maintenance practices. Furthermore, the Board did not make its assessment solely on the basis that the gas standards contained requirements tied to class locations; rather its assessment was that the overall standards, such as the requirement for a damage prevention program, for liquid pipelines were not as stringent in many respects as those for gas pipelines. In light of the apparent misunderstanding, Safety Recommendation P-84-26 has been classified as "Open--Unacceptable Action." We ask that the RSPA give further consideration to the merits of this recommendation in view of this clarification of the Safety Board's intent.

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 1987-06-05

Communication Type: Official Correspondence

Communication Contents: The Safety Board is pleased that the Research and Special Programs Administration (RSPA) has issued an Advance Notice of Proposed Rulemaking inviting public comments on certain proposals for amendments to the safety standards for gas or hazardous liquid pipelines. The Board is also pleased that the RSPA intends in FY 1988 to initiate a research study to determine whether there is a difference in the level of safety, as defined by Federal safety standards, between pipelines carrying hazardous liquid, including HVL, and those carrying natural gas, and the extent to which the standards should be modified or augmented. These two initiatives, when completed, should enable the RSPA to fully determine the need for implementing the requirements of this recommendation. Therefore, Safety Recommendation P-84-26 has been reclassified as "Open--Acceptable Action" pending the results of these efforts. The Board looks forward to hearing further from the RSPA on this matter.

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 1987-09-10

Communication Type: Official Correspondence

Communication Contents: On April 7, 1986, the RSPA responded that the maximum allowable operating pressure of gas pipelines was based on the maximum hoop stress levels corresponding to population densities. This was done, according to the response, to prevent long running fractures. The letter further stated that nIn contrast, stress level does not appear to be a significant factor in HVL pipeline accidents. In fact, we are not aware of any HVL pipeline accident that has involved a long-running fracture . . .” In a letter to the RSPA, the Board stated on August 20, 1986, that: . . . the Research and Special Programs Administration (RSPA) may have missed the thrust of this recommendation. The Safety Board is recommending that the safety standards for liquid pipelines be equivalent to natural gas pipeline standards . . . Based on our knowledge of the history of the ANSI B31.8 Code, the industry rationale for development of the population based class location criteria was not solely in response to its concern about fracture propagation; it was also in response to industry’s over all concern about the increasing populations residing adjacent to its pipelines which initially were located in noninhabited areas . . . Furthermore, the Board did not make its assessment solely on the basis that the gas standards contained requirements tied to class locations rather its assessment was that the overall standards were not as stringent in many respects as those for gas pipelines. The Board classified Safety Recommendation P-84-26 as “Open-Unacceptable Action.” In a letter dated March 2, 1987, the RSPA stated that it had issued, an Advance Notice of Proposed Rulemaking (ANPRM) on amendments to the safety standards for gas and hazardous liquid pipelines. The ANPRM issued at 52 FR 4361 on February 11, 1987, Docket P-92, was based, according to the RSPA, on various proposed legislative bills on pipeline safety. The Safety Board provided comments to the docket for this ANPRM. The Safety Board is pleased that the RSPA has issued this ANPRM and will look forward to the results of this action. The Board reclassified Safety Recommendation P-84-26 as “Open-Acceptable Action.” In the same letter, the RSPA informed the Safety Board that it is planning a research study in fiscal year 1988 to determine whether there is a difference in the levels of safety provided for liquid pipelines and for gas pipelines. The Safety Board believes that there is a difference and that the RSPA should take action to eliminate the difference in the levels of safety. While the WPL pipeline did not transport a material classified by 49 CFR Part 195 .as highly volatile or toxic, this accident demonstrates the need for an increased level of safety in 49 CFR Part 195. Although the area in Mounds View around the pipeline was populated when the pipeline was installed, the population increased without a corresponding change in the pipeline% level of safety. Residents of the accident area who were interviewed were relatively unaware of the pipeline’s presence and hazards, The level of safety cannot be defined by one factor alone; it is the combination of several. An increase in the population around a pipeline should effect not only its operating pressure but such facets of pipeline operation as the development of emergency plans and surveillance. Pipeline failures in populated areas require a different response than similar failures in rural areas because of the increase in the population at risk. As populated areas expand, the need for surveillance will be greater than it is in remote areas. The Safety Board believes that this accident again demonstrates the need for more stringent liquid pipeline regulations.

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 1991-04-02

Communication Type: Official Correspondence

Communication Contents: Safety Recommendation P-84-26 asked the RSPA to amend Federal regulations governing pipelines that transport highly volatile liquids to require a level of safety for the public comparable to that now required for natural gas pipelines. We understand that the RSPA is currently assessing the differences between the gas pipeline safety regulations with regard to proximity to population. The RSPA plans to propose regulations for hazardous liquid pipelines, including highly volatile liquids pipelines, that consider proximity to population. Since this recommendation is more than 5 years old, the Safety Board urges the RSPA to proceed as rapidly as possible so that Federal pipeline safety regulations can be instituted accordingly. Safety Recommendation P-84-26 has been classified as "Open--Acceptable Response."

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 1991-12-20

Communication Type: Official Correspondence

Communication Contents: Safety Recommendation P-84-26 requested the RSPA to amend Federal regulations governing pipelines that transport highly volatile liquids to require a level of safety for the public comparable to that now required for natural gas pipelines. The Safety Board understands that the RSPA is conducting a study of the need to amend the regulations to establish more stringent safety standards for hazardous liquid pipelines in populated areas. Further rulemaking action will be taken if justified by the conclusions of the study. The RSPA is deferring the completion of the study pending finalization of proposed pipeline safety reauthorization bills, H.R. 1489 and S. 1583. Pending enactment of this legislation, Safety Recommendation P-84-26 will be classified as "Open--Acceptable Response."

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 1994-04-22

Communication Type: Official Correspondence

Communication Contents: THE BOARD CONSIDERED NATURAL GAS PIPELINE SAFETY REQUIREMENTS SUPERIOR TO THOSE FOR LIQUID PIPELINES. ON FEBRARY 4, 1994, THE OPS ISSUED A FINAL RULE, "OPERATION & MAINTENANCE PROCEDURES FOR PIPELINE," WHICH REQUIRES THAT OPERATION & MAINTENANCE PROCEDURES FOR BOTH NATURAL GAS & LIQUID PIPELINE BY MORE CONSISTENT. ALTHOUGH THE ACTION PARTIALLY SATISFIES THE OBJECTIVE OF P-84-26, SIMILAR MEASURES ARE NEEDED IN MANY OTHER AREAS, SUCH AS ESTABLISHING CRITERIA FOR THE PERFORMANCE OF SYSTEMS USED TO MONITOR THE OPERATION OF PIPELINES. WE ENCOURGE YOUR CONTINUING EFFORTS ON THIS ISSUE & WILL MAINTAIN P-84-26 IN AN "OPEN--ACCEPTBABLE RESPONSE" STATUS.

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 1998-07-27

Communication Type: Official Correspondence

Communication Contents: THE BOARD IS DISAPPOINTED THAT THE FINAL RULES, PUBLISHED IN 1994, DO NOT REQUIRE A DIFFERENCE IN MAXIMUM OPERATING PRESSURE BASED ON RURAL OR URBAN LOCATION, & THAT OFFICE OF PIPELINE SAFETY (OPS)(RSPA BELIEVES THE LIQUID PIPELINE REQUIREMENTS IN POPULATED AREAS DO NOT NEED TO MEET REQUIREMENTS COMPARABLE TO THOSE FOR GAS PIPELINES IN POPULATED AREAS, AS RECOMMENDED . ACCORDINGLY P-84-26 HAS BEEN CLASSIFIED "CLOSED--UNACCEPTABLE ACTION."

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 1994-02-22

Communication Type: Official Correspondence

Communication Contents: -From Carl W. Vogt, Chairman: The National Transportation Safety Board has reviewed the actions taken by the Research and Special Programs Administration's (RSPA's) Office of Pipeline Safety (OPS) in response to Safety Recommendations P-78-24, P-84-26, P-87-9 and -21, and P-90-21. Safety Recommendations P-78-24 asked RSPA to amend 49 CFR 192.181(a) to specifically define the requirement for location and number of emergency valves. In response to this recommendation, the Associate Administrator for Pipeline Safety issued Advisory Bulletin 94-02 on January 13, 1994. That bulletin provided operators of gas distribution systems with the OPS criteria for selecting emergency valve locations in high-pressure distribution systems. The Safety Board has reviewed those criteria and has determined that their use by OPS and State personnel in compliance assessments will achieve the intended objective. Therefore, Safety Recommendation P-78-24 is classified "Closed--Acceptable Alternate Action." Safety Recommendation P-84-26 asked RSPA to amend Federal regulations governing the pipelines that transport highly volatile liquids (49 CFR Part 195) to require a level of safety for the public comparable to that now required for natural gas pipelines (49 CFR Part 192). The Safety Board considered natural gas pipeline safety requirements superior to those for liquid pipelines. On February 4, 1994, the OPS issued a Final Rule, “Operation and Maintenance Procedures for Pipelines,” which requires that operation and maintenance procedures for both natural gas and liquid pipelines be more consistent. Although the action partially satisfies the objective of Safety Recommendation P-84-26, similar measures are needed in many other areas, such as establishing criteria for the performance of systems used to monitor the operation of pipelines. We encourage your continuing efforts on this issue and will maintain Safety Recommendation P-84-26 in an "Open—Acceptable Response” status. Safety Recommendation P-87-9 asked RSPA to amend 49 CFR Part 192 to eliminate the" grandfather clause" that permits operators of pipelines installed before November 12, 1970, to operate at levels of stress that exceed those levels permitted for pipelines installed after the effective date. In its letter of September 2, 1992, RSPA advised the Safety Board that on December 11, 1989, it had issued a rulemaking proposal and invited the public to comment on the action RSPA should take on the "grandfather clause." RSPA noted that at the time it adopted the grandfather exception, it did not have information to justify requiring operators to lower the pressure in the grandfathered lines. RSPA also conducted a study on the causes and frequency of gas accidents in pipelines operating above 72 percent of the specified minimum yield strength (SMYS) of the steel from which the pipes were manufactured. The September 2, 1992, letter advised the Safety Board that RSPA could not conclude, based on the comments to the rulemaking or on the study results, that grandfathered lines require special treatment when they operate above 72 percent of SMYS. Therefore, on September 9, 1992, RSPA withdrew its rulemaking proposal and asked the Safety Board to close this recommendation. After our review of RSPA's actions, the Safety Board agrees that this recommendation should be closed and has classified Safety Recommendation P-87-9 "Closed--Reconsidered." Safety Recommendation P-87-21 asked RSPA to increase its use of sanctions as a means for motivating operator compliance with Federal pipeline safety standards. OPS and Safety Board staffs compiled information on the compliance actions taken by the OPS before and after issuance of this recommendation. The data show that the OPS reduced its reliance on warning letters from about 70 percent in 1985 to only 20 percent in 1991, the latest year for which that information was available. Conversely, reliance on civil penalties increased each year--from 9 in 1987 to 72 in 1992. Based on this 6-year record of stepping up the use of sanctions to improve operator compliance, the Safety Board has classified Safety Recommendation P-87-21 "Closed--Acceptable Action." Safety Recommendation P-90-21 asked RSPA to "assess existing gas industry programs for educating the public on the dangers of gas leaks and on reporting gas leaks to determine the appropriateness of information provided, the effectiveness of educational techniques used and those techniques used in other public education programs, and based on its findings, amend the public education provision of the Federal regulations. Safety Board and RSPA staff discussed this recommendation on October 29, 1992. During that meeting, Safety Board staff noted that gas-industry public education programs appear to receive less than half as much public recognition as other public education programs, such as those that promote the use of seatbelts and child restraints. Safety Board personnel explained that RSPA needs to identify the techniques that make other public education programs more effective, determine which of them would improve gas-industry programs, and incorporate them into the Federal requirements. On April 5, 1993, the OPS issued Advisory Bulletin ADB-93-02, which directed 11 gas pipeline facility owners and operators to review and assess their continuing education programs as applied to customers and the public." That bulletin included pertinent information on the accidents investigated by the Safety Board, and in part, it cited Safety Recommendation P-90-21. It advised all natural gas owners and operators to review and assess their continuing education programs to "assure that they are in compliance with the provisions of 49 CFR 192.615(d)." Although the bulletin probably prompted most operators to review their programs, the Safety Board does not regard it as responsive to Safety Recommendation P-90-21 or consistent with the discussions on October 29, 1992, between RSPA and Safety Board staff. The Safety Board encourages RSPA to perform the evaluations necessary to accomplish the recommended action and has classified Safety Recommendation P-90-21 “Open--Unacceptable Response.” The Safety Board appreciates the steps RSPA has taken to improve pipeline safety, but we also encourage your continuing support for the objectives not yet realized.

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 1998-03-11

Communication Type: Official Correspondence

Communication Contents: (Letter Mail Controlled 3/17/98 5:55:08 PM MC# 980349) THIS RECOMMENDATION WAS MADE RECOGNITION OF THE DIFFERENT TREATMENT THAT RSPA'S PIPELINE SAFETY REGULATIONS AFFORD GAS & HAZARDOUS LIQUID PIPELINES WHEN POPULATION DENSITY INCREASES NEAR A PIPELINE. AS DISCUSSED IN DETAIL BELOW, THE HAZARDOUS LIQUID REGULATIONS DO NOT REQUIRE A DIFFERENCE IN MAXIMUM OPERATING PRESSURE BASED ON RURAL OR URBAN LOCATION. THIS IS BECAUSE OF THE PHYSICAL DIFFERENCES BETWEEN THE DANGERS POSED BY GAS & LIQUID PIPLINE FAILURES. HOWEVER, THE REGULATION DO CONTAIN A NUMBER OF SPECIAL REQUIREMENTS FOR PIPELINES CARRYING HIGHLY VOLATILE LIQUIDS (HVLS). FOR EXAMPLE, 49 CFR PART 195 CONTAINS SPECIAL PROVISIONS FOR HVL PIPELINES, INCLUDING REQUIREMENTS FOR MOVING, WELDING, & INSPECTING HVL PIPELINES IN POPULATED AREAS. UNDER THE GAS REGULATIONS (49 CFR PART 192), OPERATORS MUST DESIGN & TEST THEIR PIPELINES TO STANDARDS THAT INCREASE IN STRINGENCY WITH INCREASES IN POPULATION DENSITY. IN ADDITION, THEY MUST RETEST, REPLACE, OR REDUCE THE PRESSURE ON PIPELINES WHERE THE STRESS IN THE PIPE WALL IS INCOMPATIBLE WITH INCREASES IN POPUATION DENSITY. AS A RESULT, GAS PIPELINE IN AREAS OF HIGH POPULATION DENSITY ARE OPERATED AT LOWER STRESSES THAN GAS PIPELINES IN AREA OF LOW POPULATION DENSITY. IN CONTRACT, THE REGULATIONS FOR HAZARDOUS LIQUID PIPELINES (49 CFR PART 195) DO NOT REQUIRE COMPARABLE ACTION- THE MAXIMUM ALLOWABLE STRESS DOES NOT DECREASE & REQUIRE TEST LEVEL DOES NOT INCREASE WITH AN INCREASE IN POPULATION DENSITY. THIS DIFFERENCE IN TREATMENT IS EXPLAINED BY THE PHYSICAL DIFFERENCES BETWEEN GAS & HAZARDOUS LIQUID PIPELINE OPERATIONS. BECAUSE GAS IS COMPRESSIBLE, THE STORED ENERGY IN A GAS PIPELINE CAN CAUSE FAILURE TO PROPAGATE LONG DISTANCES. IN CONTRAST, BECAUSE LIQUIDS ARE RELATVELY INCOMPRESSIBLE, A HARZARDOUS LIQUID PIPELINE FAILURE WILL DEPRESSURIZE RAPIDLY & A PRESSURE WAVE WILL NOT PROGAGATE OVER LONG DISTANCES. ALSO, BECAUSE OF THE WAY HAZARDOUS LIQUID PIPELINES ARE OPERATED, A LINEAR PRESSURE DROP OCCURS BETWEEN PUMP STATIONS. THIS PRESSURE DROP CAUSES HAZARDOUS LIQUID PIPELINES TO HAVE MUCH LOWER AVERAGE STRESS LEVELS OVER EACH SPAN OF PIPE THAN GAS PIPELINES OPERATED AT THE SAME NOMINAL PRESSURE. THE STRESS ALONG A HAZARDOU LIQUID PIPELINE DECREASE SHARPLY WITH DISTANCE FROM THE LAST UPSTREAM PUMP STATION, DIMINISHING THE VALUE OF IMPOSING ADDITIONAL STRESS LIMITATIONS BASED ON POPULATION DENSITY. OUR PIPELINE SAFETY DATA SHOW THAT MOST LIQUID PIPELINE ACCIDENTS, INCLUDING ACCIDENTS ON PIPELINE CARRYING HIGHLY VOLATILE LIQUIDS, ARE CAUSED BY CORROSION, OUTSIDE FORCE DAMAGE, & OTHER FACTORS THAT ARE UNRELATED TO STRESS LEVELS OR TEST LEVELS. GIVEN THIS ACCIDENT HISTORY & THE BEHAVIORAL DIFFERENCES DESCRIBED ABOVE, IT IS NOT REASONALBE TO EXPECT THAT REDUCTION IN ALLOWABLE STRESS LEVEL OR INCREASE IN PRESSURE TEST LEVEL IN AREAS OF HIGH POPULATION DENSITY WOULD BE JUSTIFIED FOR THE OPERATION OF HIGHLY VOLATILE LIQUID PIPELINES.

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 1986-04-07

Communication Type: Official Correspondence

Communication Contents: The recommendation resulted from an accident in a mobile home park near West Odessa, Texas on March,15,1983, in which a power auger being used to plant trees struck a buried pipeline carrying liquefied petroleum gas. The Board found that since 1960, when the pipeline was built, its design and operation had not been changed to reflect the nearby increases in population. It was noted that unlike the regulations for gas pipelines (49 CFR Part 192), the Federal regulations for highly volatile liquid (HVL) pipelines (49 CFR Part 195) do not require operators to reevaluate or increase a pipeline’s “margin of safety” provided by its maximum allowable operating pressure (MAOP) whenever the nearby population increases significantly. Under 49 CFR 192.611, the MAOP of gas pipelines must be confirmed or revised according to maximum hoop stress levels that correspond to population densities. In general, as the population near a gas pipeline increases (to levels set by a classification scheme in §192.5), the maximum hoop stress level decreases (varying from 72 percent of specified minimum yield strength in remote areas to 40 percent in densely populated areas) and the pipeline’s MAOP must be confirmed or decreased accordingly. In an area of increased population, an operator who wishes to maintain the flow of a pipeline operating at a high hoop stress usually must replace the pipeline, using either a higher strength material or the same material with a greater wall thickness. Replacement can be costly, depending on the length of line section involved. The purpose of reevaluating the operating hoop stress level of gas pipelines on a population basis is to combat their susceptibility to long-running fractures. Fracture propagation of this type, which is caused by the high energy revels of compressed gas, can be catastrophic in highly populated areas. Under the theory of the gas regulations, the risk of such an event is reduced by increasing, in relation to population density, the margin between the operating hoop stress and the stress at which yield would occur. The larger the margin, the larger the accidental overloading a pipeline can withstand before failure, thus reducing the chance that a lo~running fracture will occur. In contrast, stress level does not appear to be a significant factor in HVL pipeline accidents. In fact, we are not aware of any HVL pipeline accident that has involved a long-running fracture like that found in gas transmission line accidents. This difference’in the behavior of gas and HVL pipelines exists because HVL pipelines are usually much smaller in diameter than the gas pipelines that are subject. To fracture propagation. Also, the stored energy of an HVL pipeline dissipates much faster than a gas pipeline after a failure occurs. Because of this more rapid decompression, fractures do not propagate over long distances, and the resulting rupture is localized. Thus, we have not adopted a population density concept for the operating hoop stress level of HVL pipelines. Likewise, the industry code for hazardous liquid pipelines, ANSI B31.4, does not use a population density concept for the operating hoop stress level of HVL pipelines, although one is used by the industry code for gas pipelines, ANSI B31.8. Furthermore, a population density concept for the operating hoop stress of HVL pipelines would have limited application compared to gas pipelines. Because of the physical differences between liquid and gas, liquid pipelines operate at much lower average hoop stress levels than gas pipelines. Consequently, HVL pipelines operate to a large extent below the hoop stress levels that would be prescribed by population density rules comparable to those of Part 192. A better solution to the population density problem that the Odessa accident represents is enactment of State damage prevention laws. Many States, although not Texas, have such laws, which require excavators to notify underground utility operators of their intended excavations. The operators must respond by identifying their facilities, usually through surface marking, before excavation begins. We recommend that NTSB stepup its promotion of State damage prevention laws and the associated local coordinating committees and voluntary “one call” systems. In Texas we will be working toward that end with the Texas Railroad Commission. Like all State agencies that enforce the Department’s gas or hazardous liquid pipeline safety regulations, the Commission is required as part of its annual certification to encourage and promote pipeline damage prevention programs. In conclusion, considering the lack of any significant relationship between operating hoop stress and the cause or severity of HVL pipeline accidents, we think the existing Part 195 approach to safety, which focuses on sound design and adequate testing and maintenance, is satisfactory. There is no need to impose the costly operating hoop stress rules of Part 192 on the nation’s HVL pipelines. Therefore, we believe that Recommendation P-84-26 should be classified “Closed-Acceptable Action.”

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 1987-03-02

Communication Type: Official Correspondence

Communication Contents: WE HAVE RECENTLY ISSUED AN EXTENSIVE ANPRM FOR AMENDMENTS TO THE SAFETY STANDARDS FOR GAS OR HAZARDOUS LIQUID (INCLUDING HIGHLY VOLATILE LIQUIDS (HVL) PIPELINES. IN ADDITION TO THE ANPRM IN FY 1988 THE RSPA WILL INITIATE A RESEARCH STUDY TO DETERMINE WHETHER THERE IS A DIFFERENCE IN THE LEVEL OF SAFETY, AS DEFINED BY FEDERAL SAFETY STANDARDS, BETWEEN PIPELINES CARRYING HAZARDOUS LIQUID, INCLUDING HVL, AND THOSE CARRYING NATURAL GAS, AND THE EXTENT TO WHICH THE STANDARDS SHOULD BE MODIFIED OR AUGMENTED. LASTLY, RSPA IS CONDUCTING A STUDY TO DETERMINE IF LIQUID PIPELINE COMPANIES SHOULD BE REQUIRED TO PARTICIPATE IN DAMAGE PREVENTION PRO GRAMS. THE PURPOSE OF THE STUDY IS TO ESTIMATE HOW MUCH SAFETY IMPROVEMENT, IF ANY, COULD BE EXPECTED IF ALL HAZARDOUS LIQUID PIPELINE COMPANIES PARTICIPATE IN DAMAGE PREVEN TION PROGRAMS, AND THE COSTS ASSOCIATED WITH IMPOSING SUCH REQUIREMENTS ON THESE PIPELINE COMPANIES. IN SUMMARY, RSPA IS STUDYING, GATHERING COMMENTS AND CONDUCTING RESEARCH ON WHETHER THE STANDARDS FOR HVL PIPELINE CURRENTLY PROVIDE, OR NEED TO BE MODIFIED IN ORDER TO PROVIDE A LEVEL OF SAFETY COMPARABLE TO THAT REQUIRED FOR NATURAL GAS PIPELINES. AFTER THESE ACTIVITIES ARE COMPLETED, WE WILL ADVISE YOU OF THE RESULTS OF OUR FOLLOW-UP ACTION.

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 1990-11-27

Communication Type: Official Correspondence

Communication Contents: RSPA IS CURRENTLY CONDUCTING A TECHNICAL STUDY ASSESSING THE DIFFERENCES BETWEEN THE GAS PIPELINE SAFETY REGULATIONS AND THE HAZARDOUS LIQUID PIPELINE SAFETY REGULATIONS WITH REGARD TO PROXIMITY TO POPULATION. BASED ON THE RESULTS OF THAT STUDY, WE WILL PROPOSE REGULATIONS FOR HAZARDOUS LIQUID PIPELINES, INCLUDING HIGHLY VOLATILE LIQUIDS PIPELINES, THAT CONSIDER PROXIMITY TO POPULATION.

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 1991-10-18

Communication Type: Official Correspondence

Communication Contents: WE ARE CONDUCTING A STUDY OF THE NEED TO AMEND THE REGULATIONS TO ESTABLISH MORE STRINGENT SAFETY STANDARDS FOR HAZARDOUS LIQUID PIPELINES IN POPULATED AREAS. WE INDICATED FURTHER RULEMAKING ACTION ON THIS PROPOSAL WOULD BE TAKEN IF JUSTIFIED BY THE CONCLUSIONS OF THE STUDY. THE STUDY IS MEALY COMPLETE. WE ARE DEFERRING ITS COMPLETION, PENDING FINALIZATION OF REAUTHORIZATION LEGISLATION CURRENTLY BEING DEVELOPED IN CONGRESS, H.R. 1489, S. 1583.

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 1994-02-24

Communication Type: Official Correspondence

Communication Contents: ON FEBRUARY 4, 1994, FINAL "OPERATION AND MAINTENANCE PROCEDURES FOR PIPELINES" WAS ISSUED.

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 1992-04-09

Communication Type: Official Correspondence

Communication Contents: RSPA IS CONDUCTING A STUDY OF THE NEED TO AMEND THE REGULATIONS TO ESTABLISH MORE STRINGENT SAFETY STANDARDS FOR HAZARDOUS LIQUID PIPELINES IN POPULATED AREAS. THE STUDY IS NEARLY COMPLETE. WE ARE DEFERRING ITS COMPLETION, HOWEVER, PENDING FINALIZATION OF REAUTHRIZATION LEGISLATION CURRENTLY BEING DEVELOPED IN CONGRESS. WE WANT TO EXPAND THE SCOPE OF THE STUDY TO INCLUDE ENVIRONMENTAL CONSIDERATIONS IN ADDITION TO SAFETY CONSIDERATIONS.

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 1992-08-31

Communication Type: Official Correspondence