# Hazardous Materials: Requirements for Cargo Tanks

- **operation:** document
- **citation:** 66 FR 63096
- **title:** Hazardous Materials: Requirements for Cargo Tanks
- **source type:** rulemaking
- **agency:** Research and Special Programs Administration
- **status:** proposed
- **official:** true
- **published on:** 2001-12-04
- **effective on:** Not available
- **summary:** RSPA is proposing a number of revisions to the Hazardous Materials Regulations to update and clarify the regulations on the construction and maintenance of cargo tank motor vehicles. This proposed rule also addresses three National Transportation Safety Board (NTSB) recommendations and several petitions for rulemaking. By updating and clarifying the regulations, addressing the NTSB recommendations, and responding to petitions for rulemaking, these revisions should increase the safety of cargo tanks transporting hazardous materials, provide greater flexibility in design and construction of cargo tanks, and reduce operating burdens for owners, operators, and manufacturers of cargo tank motor vehicles.
- **machine formats:** - **json:** https://regulus.evalyn.ai/document/federal-register-01-28117.json
- **markdown:** https://regulus.evalyn.ai/document/federal-register-01-28117.md
- **app url:** https://regulus.evalyn.ai/document/federal-register-01-28117
- **source url:** https://www.federalregister.gov/documents/2001/12/04/01-28117/hazardous-materials-requirements-for-cargo-tanks
**body:**

Federal Register, Volume 66 Issue 233 (Tuesday, December 4, 2001) [Federal Register Volume 66, Number 233 (Tuesday, December 4, 2001)] [Proposed Rules] [Pages 63096-63126] From the Federal Register Online via the Government Publishing Office [ www.gpo.gov ] [FR Doc No: 01-28117] [[Page 63095]] ----------------------------------------------------------------------- Part II Department of Transportation ----------------------------------------------------------------------- Research and Special Programs Administration ----------------------------------------------------------------------- 49 CFR Parts 107, 171, et al. Hazardous Materials: Requirements for Cargo Tanks; Proposed Rule Federal Register / Vol. 66, No. 233 / Tuesday, December 4, 2001 / Proposed Rules [[Page 63096]] ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION Research and Special Programs Administration 49 CFR Parts 107, 171, 172, 173, 177, 178, and 180 [Docket No. RSPA-98-3554 (HM-213)] RIN 2137-AC90 Hazardous Materials: Requirements for Cargo Tanks AGENCY: Research and Special Programs Administration (RSPA), DOT. ACTION: Notice of proposed rulemaking (NPRM). ----------------------------------------------------------------------- SUMMARY: RSPA is proposing a number of revisions to the Hazardous Materials Regulations to update and clarify the regulations on the construction and maintenance of cargo tank motor vehicles. This proposed rule also addresses three National Transportation Safety Board (NTSB) recommendations and several petitions for rulemaking. By updating and clarifying the regulations, addressing the NTSB recommendations, and responding to petitions for rulemaking, these revisions should increase the safety of cargo tanks transporting hazardous materials, provide greater flexibility in design and construction of cargo tanks, and reduce operating burdens for owners, operators, and manufacturers of cargo tank motor vehicles. DATES: Comments must be received by February 4, 2002. To the extent possible, we will consider comments received after this date in making our decision on a final rule. ADDRESSES: Address comments to the Dockets Management System, U.S. Department of Transportation, 400 Seventh Street, SW, Washington, D.C. 20590-0001. Commenters should identify the docket number [RSPA-98-3554 (HM-213)] and submit two copies. If you wish to receive confirmation of receipt of your written comments, include a self-addressed, stamped postcard. You may also submit comments to the docket electronically by accessing the Dockets Management System website at `` http://dms.dot.gov .'' Click on ``Help & Information'' to obtain instructions for filing the document electronically. The Dockets Management System is located on the Plaza level of the Nassif Building at the Department of Transportation at the above address. You may view public dockets between the hours of 9 a.m. and 5 p.m. EST, Monday through Friday, except Federal holidays. Internet users may review all comments received by the U.S. Department of Transportation by accessing the Dockets Management System website at http://dms.dot.gov . FOR FURTHER INFORMATION CONTACT: Mr. Michael Johnsen, Office of Hazardous Materials Standards, RSPA, telephone (202) 366-8553; Mr. Philip Olson, Office of Hazardous Materials Technology, RSPA, telephone (202) 366-4545; or Mr. Danny Shelton, Office of Enforcement and Program Delivery, Hazardous Materials Division, Federal Motor Carrier Safety Administration (FMCSA), telephone (202) 366-6121. SUPPLEMENTARY INFORMATION: All comments received before the close of business on the comment closing date will be considered and will be available for examination in the docket room indicated in the ADDRESSES section. Comments received after the comment closing date will be filed in the docket and will be considered to the extent practicable. In addition to late comments, RSPA will also continue to file, in the docket, relevant information that becomes available after the close of the comment period. Interested persons should periodically examine the docket for new material. Comments should include any relevant data or referenced factual information. In addition, RSPA asks that commenters provide justification for any suggested changes to this NPRM. List of Topics I. Background II. Proposed Revisions Applicable to All Cargo Tanks A. Definitions B. Marking of Emergency Shutoff Devices C. Recertification to Original Specification D. Cargo Tank Qualification and Maintenance III. Revisions Applicable to DOT 400-Series Cargo Tanks A. Structural Integrity Requirements B. Manhole Marking C. Road Clearance D. MAWP Specification Plate Marking E. Leak Testing Using EPA Method 27 F. Weld Joints on DOT 407 Cargo Tanks IV. Revisions Applicable to MC 331 and MC 338 Cargo Tanks A. Consistency With DOT 400-series Specification B. Remote Shutoffs C. Inlet and Outlet Fittings on MC 331 Cargo Tanks D. Internal Visual Inspections of Insulated Tanks E. Leakage Tests for Cargo Tanks in Anhydrous Ammonia Service V. Petitions for Rulemaking and Other Recommendations VI. Section-by-Section Review VII. Rulemaking Analysis and Notices A. Executive Order 12866 and DOT Regulatory Policies and Procedures B. Executive Order 13132 C. Executive Order 13175 D. Regulatory Flexibility Act E. Paperwork Reduction Act F. Regulation Identifier Number (RIN) G. Unfunded Mandates Reform Act H. Environmental Assessment I. Background On June 12, 1989, the Research and Special Programs Administration (RSPA; we) published a final rule in the Federal Register (Docket HM- 183, 183A; 54 FR 24982) that revised the Hazardous Materials Regulations (HMR; 49 CFR Parts 171 through 180) pertaining to cargo tank motor vehicles. We further revised the regulations each year from 1990 through 1995 under dockets HM-183, HM-183A, and HM-183C. Several of these dockets made significant changes to the cargo tank regulations to improve safety; other revisions corrected mistakes and made minor changes. Dockets HM-183 and 183A established the DOT 400 series cargo tank specifications, as well as certification requirements for cargo tank manufacturers. Docket HM-183C contained a number of miscellaneous items that clarified and relaxed certain requirements for the manufacture, qualification, and maintenance of cargo tank motor vehicles. Under 49 CFR 1.73(d), the Federal Motor Carrier Safety Administration (FMCSA) is delegated authority to enforce the HMR, with particular emphasis on highway transportation, including regulations for construction and maintenance of cargo tank motor vehicles (CTMVs). FMCSA and RSPA work closely with the regulated industry through educational assistance activities and FMCSA's compliance and enforcement program. During these activities, we identified several areas in the current regulations that need updating or clarification. In addition, we received requests for clarification of the regulations and petitions for rulemaking. The National Transportation Safety Board (NTSB) has also made several safety recommendations concerning cargo tanks. In this NPRM, we are proposing revisions that would apply to all cargo tanks and revisions that would apply to certain specification cargo tanks or cargo tanks used to transport certain ladings. II. Proposed Revisions Applicable to All Cargo Tanks A. Definitions General. Under Docket HM-183, we adopted a number of definitions for DOT 400-series specification CTMVs. The definitions apply to all specification CTMVs used to transport [[Page 63097]] hazardous materials. Thus, in this NPRM we are proposing to combine the definitions currently in Sec. 178.345-1(c) with the definitions in Sec. 173.320(a) and make them applicable to all specification CTMVs. Minimum thickness. We propose to add in Sec. 178.320 a definition for ``minimum thickness'' to clarify how the minimum head and shell thickness for specification cargo tanks must be determined. The proposal defines ``minimum thickness'' to mean the least of: (1) The thickness required by the tables in the original specification; (2) the thickness required to satisfy the structural integrity and accident damage requirements; or (3) the thickness required to satisfy the requirements of the American Society of Mechanical Engineers (ASME) Code, if applicable. This proposal should eliminate confusion as to whether the minimum thickness tables in Sec. 180.407(i) are the governing factor in determining minimum thickness. It is possible that the minimum thickness value prescribed by the ASME Code or the structural integrity requirements may be greater than that required by the minimum thickness tables. For example, an MC 307 cargo tank was manufactured using 10-gauge (0.1345 inches) steel. Upon conducting a thickness test, an inspection/testing facility measured the thickness of the tank at 0.12 inches, which is lower than the 0.1345 inches specified in Table I of Sec. 180.407(i)(5) for 10-gauge steel. However, the MC 307 cargo tank was only required to be manufactured using 12- gauge steel (0.1046 inches) as specified in Part 178. Therefore, the thickness of this tank is above the minimum thickness (0.1046 inches) prescribed for this cargo tank and the cargo tank is suitable for continued service. Maximum allowable working pressure. Currently, the HMR require a cargo tank's maximum allowable work pressure (MAWP) to be determined based on the lading that will be transported in the cargo tank or the maximum pressure in the tank during loading or unloading. The Truck Trailer Manufacturers Association (TTMA) submitted a petition for rulemaking (P-1272) suggesting that a cargo tank's MAWP should be dependent on the physical characteristics of the cargo tank rather than the lading carried in the cargo tank or the method of loading or unloading the cargo tank. In its petition, TTMA notes that a cargo tank manufacturer will not always know the characteristics of the lading that will be transported in the cargo tank and that a manufacturer will not always know the pressure at which the tank will be loaded or unloaded. In its petition, TTMA also asserts that the current regulations have resulted in confusion in the regulated industry as to whether the static head of lading should be included in the MAWP. TTMA notes that Sec. 178.345-1(k) defines MAWP as the largest of: (1) The pressure prescribed for the lading in part 173; (2) the vapor pressure of the most volatile lading at 115 deg.F plus the maximum static pressure exerted by the lading at the maximum lading density plus any pressure exerted by a gas padding; or (3) the maximum pressure in the cargo tank during loading or unloading. TTMA states that it is not clear if the static head is included in the lading pressure prescribed in Part 173 or the loading/unloading pressure. We agree with TTMA that there should be no ambiguity in the HMR as to the meaning of MAWP. We also agree that the MAWP should be based on the cargo tank's physical characteristics, but we believe MAWP should also be linked to the requirements of Sec. 173.33 for use by shippers and carriers. The proper matching of the maximum lading pressure conditions defined in Sec. 173.33(c) with the MAWP of a cargo tank by shippers and carriers is critical to providing safety in cargo tank operations. The maximum lading pressure addresses many factors critical to matching a lading to a cargo tank MAWP, including the static head (pressure) generated by a specific lading or the maximum pressure in a tank during loading or unloading. For example, Sec. 173.33(c)(iv) requires the sum of the vapor pressure of the lading at 115 deg.F, plus the tank static head exerted by the lading, plus any pressure exerted by a gas padding, including air, in the tank to be less than or equal to the MAWP of the cargo tank. The pressure defined by this summation is the pressure exerted at the bottom of the tank. When a cargo tank is inverted in a rollover, this pressure is applied to the pressure relief devices installed on the cargo tank. Particularly for large diameter tanks and high-density ladings, this resultant pressure could be sufficient to open the cargo tank's pressure relief devices and drain the contents of the tank, even if the tank were undamaged. Thus, it is critical for shippers and carriers to determine that the MAWP of a cargo tank is greater than or equal to maximum lading pressure derived from the conditions specified in Sec. 173.33. Similarly, cargo tank manufacturers should be familiar with the requirements of Sec. 173.33 in order to provide a cargo tank with an MAWP sufficient to meet the needs of shippers and carriers. To strengthen the linkage between Sec. 173.33 and cargo tank MAWP, we are proposing to revise the definition for MAWP to require the MAWP to be greater than or equal to the maximum lading pressure condition prescribed in Sec. 173.33 for each material. Corroded/abraded. Although it is used throughout Sec. 180.407, the term ``corroded or abraded'' is not currently defined in the HMR. As a result, there have been many different interpretations concerning the type and extent of corrosion or abrasion that requires thickness testing. Some cargo tank inspection and test facilities perform thickness tests on cargo tanks that do not require such a test; other facilities fail to test cargo tanks that should be thickness tested. External corrosion on cargo tanks is a common occurrence during winter in many geographical areas. Rocks and other debris can chip paint on cargo tanks, causing surface oxidation and rust. Road salt accelerates corrosion. The new definition specifies that ``corroded or abraded'' means a reduction in the material thickness of the cargo tank that is visible to the naked eye. Corrosive to the tank/valve. We also propose to revise the definition of ``corrosive to the tank/valve'' because of the many requests for clarification that we have received. The regulations require additional and more frequent inspections (internal inspection, thickness testing, upper coupler removal and inspection) for CTMVs transporting a lading that may adversely affect tanks or valves, causing leaks and other safety hazards. The current definition of ``corrosive to the tank/valve'' includes those ladings that meet the corrosivity requirements in Sec. 173.136 for the material of construction of a cargo tank/valve (6.25 mm per year), and other lading where experience shows corrosion exists. The reference to Sec. 173.136 (definition of a Class 8 material) in the current definition has caused confusion. We did not intend that lading designated as ``corrosive to the tank/valve'' would be limited to Class 8 materials or to materials that cause corrosion at a rate of 6.25 mm or more per year. Our intent was to include any lading, not just those classed as Class 8 materials, that corrodes a tank or valve. The proposed change to the definition of ``corrosive to the tank/ valve'' specifies that test data and experience must be used to determine if a specific lading is corrosive to the cargo tank wall or valve. The removal of the reference to Sec. 173.136 is intended to clarify that ``corrosive to the tank/valve'' is not limited to materials with a corrosion [[Page 63098]] rate of 6.25 mm or more per year. Under this proposal, any test data or experience that indicates any amount of corrosion is sufficient to meet the definition. We welcome comments on any existing sources of corrosion data. B. Marking of Emergency Shutoff Devices On May 12, 1993, in Rockville, Maryland, gasoline overflowed from an underground storage tank while it was being filled from an MC 306 CTMV. The gasoline ignited, causing a fire that spread to an adjacent building. The first firefighters on the scene stopped the flow of gasoline by closing the gate valves in a manifold at the rear of the cargo tank. The first responders were unaware of the on-truck remotely actuated means for closing the cargo tank's internal valve. A hazardous materials officer arrived at the scene and activated the on-truck remote shutoff device; however, the inability of the first responders to locate the shutoff device resulted in a risk that could have been avoided. As a result of its investigation of this incident, the NTSB recommended that RSPA require existing and new cargo tank motor vehicles with on-truck remote control mechanisms for internal shutoff valves to be marked for emergency use on all cargo tanks authorized for the transportation of hazardous materials (NTSB # H-93-34). In response to this recommendation, we are proposing to amend the HMR to require all manually activated on-truck remote shutoff devices for closure of the internal valve to be marked ``Emergency Shutoff.'' The requirement would be effective two years after the publication date of a final rule. C. Recertification to Original Specification There appears to be confusion in the regulated industry as to whether cargo tanks that have been modified for specialized or non- hazardous materials service may be re-certified for hazardous materials service. In this NPRM, we propose to allow for the re-certification of a cargo tank to its original specification, provided specific requirements are met. These requirements include documentation to verify that the cargo tank was originally manufactured to a DOT specification, verification by a Registered Inspector that the cargo tank is in compliance with the requirements of the specification, and certification that the cargo tank successfully passed all required tests and inspections. In addition, any repairs performed on MC 306, MC 307, or MC 312 cargo tanks after June 30, 1992, will have to have been performed in accordance with requirements in Sec. 180.413. An example of a cargo tank that may be recertified to its original specification is an MC 306 cargo tank where its internal self-closing stop valve was removed so that the tank could be used to transport asphalt. As proposed in this NPRM, the cargo tank may be re-certified to its original specification provided an internal shutoff valve is reinstalled, the CTMV meets all other requirements of the specification, and the cargo tank motor vehicle has successfully passed the inspections and tests required in Sec. 180.407(c). D. Cargo Tank Qualification and Maintenance We are proposing a number of clarifications to the requirements in Part 180 for cargo tank qualification and maintenance to eliminate confusion. For example, we are proposing to clarify the tests and inspections that must be performed when a cargo tank shows evidence of dents, corroded or abraded areas, or leakage; has sustained damage to an extent that may adversely affect its lading retention capability; or has any other condition that could render it unsafe for the transportation of hazardous materials. In addition, consistent with an NTSB recommendation (H-95-14), we are proposing to require thickness testing of ring stiffeners and appurtenances on cargo tanks that are constructed of mild steel, high- strength, low-alloy steel, or aluminum, when the ring stiffeners and appurtenances are installed in a manner that precludes an external visual inspection. NTSB investigated two catastrophic cargo tank failures, one that occurred on March 9, 1983, in Beaumont, Texas, and the other on January 6, 1994, in Deltona, Florida. As a result of its investigations, NTSB determined that thickness testing of the cargo tanks' ring stiffeners might have detected the corrosion that caused the failures. Further, we are proposing to clarify the HMR requirements for repair, modification, stretching, or rebarrelling of cargo tanks. Currently, facilities are allowed to repair, modify, stretch, or rebarrel a non-ASME Code stamped cargo tank provided the facility has an ASME Certificate of Authorization for use of the ``U'' stamp. Full compliance with the National Board Inspection Code (NBIC) is not currently required when working on non-ASME Code stamped cargo tanks if the facility has a ``U'' stamp. In this NPRM, we are proposing to require facilities to perform repairs, modifications, stretching, or rebarrelling of cargo tanks in conformance with the NBIC. Prior to 1995, the NBIC was only applicable to tanks with an MAWP of 15 psig or greater. However, in 1995 the applicability of the NBIC was extended to all pressure vessels. While the ASME Code is applicable to new construction only, the NBIC sets forth procedures for repairing or modifying pressure vessels. Adopting the NBIC requirements in the HMR for all cargo tank repairs, modifications, stretching, and rebarrelling will provide clarity, consistency, and a greater level of safety. However, we are not proposing to adopt NBIC requirements for certification by an Authorized Inspector, completion of the R-1 form, and stamping tanks with the ``R'' stamp for non-ASME cargo tanks at this time due to cost considerations and concern about the availability of Authorized Inspectors. Because persons have suffered severe injuries or died while performing repairs to cargo tanks that were not properly cleaned and purged, we are also proposing to clarify and emphasize that the entire CTMV, including void spaces, piping, and vapor recovery systems, be cleaned and purged before doing repairs, modifications, stretchings, rebarrellings, or mountings that involve welding on cargo tanks that transport toxic or flammable lading. We also propose to clarify that modification, stretching, or rebarrelling must be inspected and certified by a Design Certifying Engineer (DCE). The current requirement for a DCE to approve modifications has caused confusion about the level of participation required from the DCE. In addition, we propose to revise specification plate requirements to reflect the modification, stretching, or rebarrelling of a cargo tank. We are proposing to require a supplemental specification plate to be installed adjacent to the original specification plate. Changes to the original specification plate would not be allowed. This proposal addresses TTMA's petition (P-1388) requesting that we require a supplemental plate for changes. However, we are not proposing to adopt TTMA's request to allow the original cargo tank manufacturer to replace the original specification plate if the cargo tank is altered. We believe that the information on the original specification plate should be permanent and not altered, even if the work is done by the original manufacturer. III. Revisions Applicable to DOT 400-Series Cargo Tanks We are proposing several revisions to the specifications applicable to the DOT [[Page 63099]] 400-series cargo tanks. These proposals include revisions to: (1) Structural integrity requirements; (2) manhole marking requirements; (3) road clearance allowances; (4) bottom accident protection; (5) specification plate marking; (6) leak testing alternatives; and (7) weld joints. In addition to these changes, which are described below, we are also proposing revisions to the DOT 400-series specifications to make the requirements easier to understand and follow. A. Structural Integrity Requirements The HMR currently do not include structural support members in the structural integrity requirements for lightweight attachments welded to DOT 400-series CTMVs. In this NPRM, we are proposing to correct this omission by adding structural support members to the list of attachments to which the structural integrity requirements apply for new construction of DOT-400 series CTMVs. B. Manhole Marking Currently, the HMR require manhole covers to be permanently marked with the manufacturer's name, the test pressure, and a certification that the manhole cover meets HMR requirements. This marking enables cargo tank owners, Registered Inspectors, and enforcement personnel to verify that the manhole conforms to applicable regulatory requirements. In this NPRM, we are proposing to specify that manhole assemblies be marked on the outside, where they can be seen without opening the manhole cover or fill opening, thereby enabling persons to see the marking without being exposed to hazardous materials inside the cargo tank. We are proposing that this requirement become effective one year after the effective date of a final rule. The revised marking requirements would apply to newly manufactured cargo tanks and cargo tanks that have their manhole assemblies replaced. C. Road Clearance The current HMR requirement for minimum allowable road clearance for DOT 400-series CTMV components or protection devices located between two adjacent axles is at least one-half inch for each foot separating the axles and in no case less than 12 inches. In a petition for rulemaking (P-1325), TTMA requests that we lower the minimum road clearance requirement to permit greater flexibility in the design of landing gear, tire carriers, cabinets, and other components near axles. TTMA suggests that such a revision would permit lowering the center of gravity for some CTMVs, which would improve dynamic stability. TTMA states that it is aware of no situations in which a landing gear failure has punctured a cargo tank. We agree with TTMA that reducing the center of gravity for CTMVs would be beneficial. Thus, in this NPRM, we are proposing to revise the requirements for minimum road clearance for landing gear within 10 feet of an axle to be no less than 10 inches. We propose to maintain the current clearance requirements for the middle area between axles. The proposed revision would allow landing gear to be lowered by two inches, but would not compromise clearances in the area of a CTMV most vulnerable to contact with the ground--that is, the area midway between a tractor's rear axle and the CTMV rear suspension. D. MAWP Specification Plate Marking Current regulations for DOT 406, DOT 407, and DOT 412 cargo tanks require the maximum loading and unloading pressure to be marked on the cargo tank's specification plate. In a petition for rulemaking (P- 1212), TTMA asks us to eliminate this marking requirement. TTMA notes that the volume change of liquids transported in DOT 406, DOT 407, and DOT 412 cargo tanks is small and that the maximum loading and unloading rate is calculated in the design of the cargo tank and identified on the specification plate. We agree that the maximum loading and unloading pressure marking is unnecessary because the maximum loading/ unloading pressure is reflected in the MAWP. Therefore we are proposing to eliminate it. However, in no situation can the actual pressure in the tank exceed the MAWP. E. Leak Testing Using EPA Method 27 Currently, the HMR permit cargo tanks equipped with vapor collection equipment to be leak tested in accordance with the Environmental Protection Agency (EPA) ``Method 27--Determination of Vapor Tightness of Gasoline Delivery Tank Using Pressure-Vacuum Test'' as set forth in Appendix A to 40 CFR part 60. We propose to clarify the parameters for testing cargo tanks that are used to transport petroleum distillate fuels and are equipped with vapor recovery equipment. EPA regulations at 40 CFR 63.425(e) require cargo tanks equipped with vapor collection systems that are used to transport petroleum distillate fuels to pass an annual certification test for vapor tightness. This annual certification test includes both the Method 27 test for vapor tightness of a cargo tank and a pressure test of the tank's internal vapor valve. The revision proposed in this NPRM specifies that cargo tanks equipped with vapor collection equipment that are used to transport petroleum distillate fuels may be tested in accordance with 40 CFR 63.425(e) instead of the annual leakage test required under Sec. 180.407 of the HMR. In addition, we are proposing that, if the EPA annual certification test in 40 CFR 63.425(e) is used to satisfy the annual leak test requirement, the Method 27 test must be conducted using air. Performing the test using liquid, an alternative allowed by EPA, may mask leakage below the liquid level at the pressure level specified for the test. The EPA Method 27 air test should detect even small leaks in a cargo tank. Therefore, we propose to prohibit use of alternative procedures in section 6 of Method 27 that allow the use of water. We are also proposing a special marking to designate cargo tanks that have been tested in conformance with EPA's annual certification test for cargo tanks equipped with vapor recovery equipment and used to transport petroleum distillate fuels. The proposed marking is ``K- EPA27.'' The marking would replace the ``K'' marking on a cargo tank if the EPA vapor tightness test methods and procedures as set forth in 40 CFR 63.425(e) are used in place of the leak test. If a cargo tank is tested using both the leak test specified in the HMR and the vapor tightness tests specified in the EPA regulations, it would be marked with both ``K'' and ``K-EPA27''. This proposal establishes a national, uniform marking requirement for cargo tanks tested for vapor tightness in accordance with EPA regulations instead of, or in addition to, the leak test procedures specified in the HMR. This new marking would be applied to cargo tanks that are tested for vapor tightness under EPA procedures beginning one year after the effective date of the final rule. F. Weld Joints on DOT 407 Cargo Tanks In a petition (P-1333), TTMA requests that we adopt a weld joint efficiency of 0.85 for head seams in bulkheads on DOT 407 cargo tanks. Based on review of the TTMA petition and additional information, we are proposing in this NPRM that the strength of a weld seam in a bulkhead without radiographic examination of the weld must be 0.85 of the strength of the bulkhead. The welded seam must be a full penetration butt weld, no more than one seam may be used per bulkhead, and the welded seam must be completed before forming the dish radius and knuckle radius. [[Page 63100]] In its petition, TTMA also requested that we permit spot radiographic examination of weld joints every six months as an alternative to the periodic test. We do not agree with TTMA. Instead, we are proposing that two test specimens of the same material and thickness and joined by the same welding procedure as those to be used in manufacturing the bulkhead must be tested to failure in tension. The ratio of the actual tensile stress to the actual tensile strength of the adjacent material of both samples must be greater than 0.85. The test specimens may represent all the tanks that are manufactured in the same facility within six months after the tests are completed. IV. Revisions Applicable to MC 331 and MC 338 Cargo Tanks We are proposing several revisions to the HMR specifications applicable to MC 331 and MC 338 cargo tanks. The proposals include: (1) Revisions to make the specifications consistent with the DOT 400-series cargo tank specification requirements; (2) retrofit requirements for cargo tanks not currently equipped with remote shutoff devices; (3) a new requirement for thermal activation devices on MC 338 CTMVs; (4) revisions to the internal inspection requirements; and (5) revisions to leakage test requirements for cargo tanks in anhydrous ammonia service. In addition to these changes, which are described below, we are also proposing revisions to the MC 331 and MC 338 specifications to make the requirements easier to understand and follow. A. Consistency With DOT 400-Series Specification We are proposing a number of changes to the MC 331 and MC 338 specifications to make them consistent with specifications applicable to DOT 400-series CTMVs. The DOT 400-series cargo tank specifications are more contemporary regulations that reflect current industry practices. In addition, the DOT 400-series specifications are performance standards, and, thus, provide greater flexibility to cargo tank designers and manufacturers to meet the DOT requirements. As proposed in this NPRM, we are not imposing additional requirements for MC 331 and MC 338 CTMVs; rather we are increasing flexibility in meeting the requirements by proposing performance standards and additional alternatives. Under Docket HM-183C (60 FR 17398), we modified the structural integrity requirements for MC 331 and MC 338 CTMVs to conform with the DOT 400-series specification requirements. At that time, however, the related requirements for attachments were not changed. Thus, we propose to make requirements for the design, construction, and installation of attachments, appurtenances, structural support members, or accident protection devices on MC 331 and MC 338 CTMVs consistent with the requirements for DOT 400-series CTMVs. Similarly, we are proposing to revise long-standing requirements for rear-end protection devices on MC 331 and MC 338 CTMVs to authorize the DOT 400-series rear-end protection provisions as an alternative to the current requirements for both MC 331 and MC 338 CTMVs. We are also proposing changes to the MC 331 and MC 338 specifications for cargo tank support and anchoring for consistency with the DOT 400-series requirements. When the structural integrity requirements for the MC 331 and MC 338 CTMVs were modified under HM- 183, the closely related requirements for support and anchoring were not changed. This was an inadvertent error that we now propose to correct. This would apply to newly constructed MC 331 and MC 338 CTMVs. We propose to require essential information marked on MC 331 and MC 338 CTMV metal specification plates to be consistent with requirements for DOT 400-series CTMVs. Thus, in addition to the information already required, the specification plate would be marked with the cargo tank test pressure; the CTMV certification date if different from the cargo tank certification date; the cargo tank certification date; the shell material specification number; the head material specification number; the maximum design density of lading; the weld material; the minimum thickness of the cargo tank shell; tank maximum allowable working pressure; cargo tank design temperature; cargo tank manufacturer; cargo tank manufacture date; maximum weight of lading; minimum thickness-- head; and exposed surface area. The requirement for Vehicle manufacturer's serial number would be removed. MC 331 cargo tanks would be required to add the information concerning linings and heating systems while MC 338 cargo tanks would be required to include information specific to this series. This requirement would apply to new construction and changes on these CTMVs. In addition, for MC 331 CTMVs, we propose to require certificates for a CTMV that is manufactured in two or more stages. Each manufacturer who performs a manufacturing function on the incomplete CTMV must provide the succeeding manufacturer with a certificate that states the function that was performed and must also provide certificates received from previous manufacturers, Registered Inspectors, and Design Certifying Engineers. Further, we propose to clarify the roles of the original manufacturer of a cargo tank and the assembler of a CTMV in documenting on the certificate those areas of the specification that are not met or specification shortages, including valves, piping, fittings, and the like. The person who installs the components that bring the tank into full compliance with the specification would be required to stamp the certification date on the specification plate and issue a Certificate of Compliance. B. Remote Shutoffs On December 28, 1988, in Ashland, Virginia, a pipe fitting on an MC 331 cargo tank transporting sulfur dioxide failed during a delivery operation. The driver of the CTMV suffered a fatal injury while attempting to close the cargo tank's internal valve. The CTMV was not equipped with a remote mechanical means to close the internal valve. As a result of its investigation, NTSB recommended that RSPA require MC 330, MC 331, and MC 338 CTMVs to be equipped with on-truck remote mechanical means to close the internal valve (NTSB # H-90-91). In a final rule published November 3, 1994 (HM-183C; 50 FR 55162), we adopted a requirement for MC 331 and MC 338 CTMVs constructed after January 1, 1995, to be equipped with on-truck remote shutoff devices. For CTMVs constructed prior to January 1, 1995, we required each MC 330 and MC 331 CTMV used to transport flammable gas; flammable liquid; hydrogen chloride, refrigerated liquid; or anhydrous ammonia, and each MC 338 CTMV used to transport flammable ladings to be retrofitted with an on-truck remote shutoff device. In this NPRM, we are proposing to require all MC 330, MC 331, and MC 338 CTMVs to be retrofitted with an on-truck remote mechanical shutoff device that meets the requirements for the applicable specification. The retrofit must be accomplished within three years from the effective date of a final rule. Under this proposal, CTMVs used to transport only argon, carbon dioxide, helium, krypton, neon, nitrogen, or xenon are excepted from the requirement for on-truck remote shutoffs. We are also proposing to require MC 338 CTMVs to be equipped with a means of thermal activation for closing the internal self-closing stop valve. On [[Page 63101]] June 4, 1998 (63 FR 30572), RSPA established a negotiated rulemaking committee under Docket RSPA-97-2718 (HM 225A). During the negotiated rulemaking process, the committee discussed the safety benefits of fusible elements, which provide a heat-activated means for closing a valve. Fusible elements melt when subjected to sufficiently high temperatures, thereby closing the valve to which they are affixed. The HMR currently require installation of on-truck remote closures with a means of thermal activation on MC 331 cargo tanks. Consistent with the committee's recommendation, we are proposing that internal self-closing stop valves be equipped with a means of thermal activation on all MC 338 cargo tanks. This requirement would not apply to tanks transporting only argon, carbon dioxide, helium, krypton, neon, nitrogen, or xenon. C. Inlet and Outlet Fittings on MC 331 Cargo Tanks Currently, Sec. 178.337-9 of the HMR requires the use of malleable metals for the construction of valves and fittings on MC 331 cargo tanks. The National Propane Gas Association (NPGA) petitioned for a change to Sec. 178.337-9 to require liquid filling and vapor equalization fittings on MC 331 cargo tanks to be constructed of malleable steel or ductile iron only (P-0935). In its petition, NPGA stated that this change would help to prevent the occurrence of piping failures when fittings made of soft metals, such as brass or copper, are struck by an outside force. We agree. Accordingly, we are proposing to require new or replacement primary valves and fittings used in liquid filling or vapor equalization on MC 331 cargo tanks to be constructed of malleable steel or ductile iron. This proposal is consistent with the National Fire Protection Association (NFPA) Standard 58 and is currently the standard industry practice. D. Internal Visual Inspections of Insulated Tanks Currently, the HMR provide an exception for insulated MC 330 and MC 331 cargo tanks from the requirement to undergo an internal visual inspection in conjunction with the annual external visual inspection. The exception was included in the HMR to facilitate inspection of insulated MC 330 and MC 331 cargo tanks that did not have manholes or inspection openings, making it impossible to enter the cargo tank to perform an internal visual inspection. Because insulation precludes a visual inspection of the exterior of the cargo tank, and there is no means to inspect the interior of the tank, it was decided that the only way to verify the structural integrity of the cargo tank was to subject it to a hydrostatic or pneumatic pressure test at one-year intervals. The exception applies to insulated MC 330 and MC 331 cargo tanks, irrespective of whether the cargo tank is equipped with a manhole or inspection opening. Ho
- **truncated:** true
- **body characters:** 197165