Restructuring of Cylinder Specifications Requirements

Federal RegisterMar 4, 1996

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SUMMARY: RSPA is proposing to revise the Hazardous Materials

Regulations (HMR) by restructuring the cylinder specification

requirements. The intended effect of this rulemaking is to reduce the

size of the HMR through consolidation of repetitive requirements and

other formatting changes. This action will eliminate pages of

regulations without substantially changing the regulatory requirements

or affecting safety. It is in response to President Clinton's March 4,

1995 Regulatory Reinvention Initiative memorandum to heads of

departments and agencies calling for a review of all agency

regulations. RSPA is also proposing to make corresponding reference

changes throughout the HMR.

DATES: Comments must be received on or before April 26, 1996.

ADDRESSES: Please address written comments to the Dockets Unit (DHM-

30), Research and Special Programs Administration, U.S. Department of

Transportation, 400 7th Street, SW., Washington, DC 20590-0001.

Comments may also be faxed to (202) 366-3753. Comments should identify

the docket (Docket No. HM-220B). The Dockets Unit is located in Room

8421 of the Nassif Building, 400 Seventh Street SW., Washington, DC

20590-0001. Office hours are 8:30 a.m. to 5:00 p.m., Monday through

Friday, except on public holidays when the office is closed.

FOR FURTHER INFORMATION CONTACT: John A. Gale, (202) 366-8553; Office

of Hazardous Materials Standards, RSPA, Department of Transportation,

Washington, DC 20590-0001.

SUPPLEMENTARY INFORMATION:

I. Background

On March 4, 1995, President Clinton issued a Regulatory Reinvention

Initiative memorandum to heads of departments and agencies calling for

a review of all agency regulations and elimination or revision of those

regulations that are outdated or in need of reform. RSPA has performed

an extensive review of the Hazardous Materials Regulations (HMR; 49 CFR

Parts 171-180) and associated procedural rules (49 CFR Parts 106 and

107) in response to the President's directive.

The President also directed that front line regulators ``* * * get

out of Washington and create grassroots partnerships'' with people

affected by agency regulations. On April 4, 1995, RSPA published in the

Federal Register (60 FR 17049) a Notice of Public Meetings and request

for comment on its hazardous materials safety program. Comments were

requested on ways to improve the HMR and the kind and quality of

services its customers want. RSPA held seven public meetings and

received over 50 comments in response to the notice. On July 28, 1995,

RSPA published a second Notice of Public Meetings in the Federal

were held from September through January 1996.

One area identified by RSPA in its review of the HMR was the need

to reform the cylinder specifications in 49 CFR Part 178. RSPA

estimates that by consolidating duplicative requirements in 23 cylinder

specifications, that it will eliminate at least 40 pages from the CFR.

By reformatting the specifications, RSPA proposes to eliminate over 450

sections from Part 178 of Title 49. The combined effect of these

changes will be to make the regulations shorter and easier to use and

help RSPA move toward a goal of being able to issue the HMR in one

volume of the Code of Federal Regulations, rather than two.

This rulemaking also serves as the model for a more comprehensive

rulemaking, being developed by RSPA in cooperation with the Compressed

Gas Association, for which a notice of proposed rulemaking is

anticipated later this year. In this latter rulemaking, under Docket

HM-220, RSPA intends to propose substantive changes to the cylinder

specifications to accommodate contemporary manufacturing techniques,

eliminate obsolete requirements, contemporize regulatory language and

make safety enhancements to the regulations.

II. Proposed Changes

In this NPRM, RSPA is proposing to revise the HMR by restructuring

the cylinder specification requirements in 49 CFR Part 178. The

proposed restructuring of the cylinder specifications would: (1)

consolidate similar sections; (2) reformat subpart C of Part 178 for

consistency with the format of the rest of Part 178; and (3) revise

section references throughout the HMR to correspond to the revised

sections. RSPA intends to streamline the cylinder specification

requirements without making substantive changes to them.

Sections that have been identified by RSPA for consolidation are

the sections of each specification addressing compliance, authorized

inspectors, duties of the inspector, the inspector's report, record

retention, defects, safety relief devices, and marking. These sections

will be consolidated into a new Sec. 178.35. Proposed Sec. 178.35,

entitled ``General requirements for all DOT specification cylinders''

will prescribe these general requirements for all DOT specification

cylinders. However, because some of the duties of the inspector and

marking requirements are specific to the individual cylinder design,

some specifications would have additional marking and inspector

requirements remaining in their sections.

For the inspector's report, RSPA has proposed to adopt the

inspector report formats in Compressed Gas Association (CGA) Pamphlet

C-11, ``Recommended Practices for Inspection of Compressed Gas

Cylinders at Time of Manufacture.'' The report formats can be modified

to represent the inspection of specific cylinders. Additional

information may be required as stated in each specification.

Those sections remaining in each specification will be consolidated

into a single section. Presently, each specification is set forth in

approximately 22 different sections. Under this proposal, there would

be only one section for each specification. For example, Specification

3B is currently set forth in 24 sections, Secs. 178.38 through 178.38-

23. In this NPRM, Specification 3B is set forth in one section,

Sec. 178.38. Some of the requirements are relocated in Sec. 178.35.

Sixteen of the old sections are converted to paragraphs (a) through (o)

of Sec. 178.38. As an aid to the reader, the regulatory text in this

notice includes all of the requirements for cylinders in the current

Subpart C of part 178, even though not all of the requirements are

changed.

The purpose of this rulemaking action is to reduce the size of the

HMR and make it easier to use. It is not intended to make substantive

changes to regulatory requirements and no adverse impacts are

anticipated on the regulated community.

[[Page 8329]]

III. Regulatory Analyses and Notices

Executive Order 12866 and DOT Regulatory Policies and Procedures

This proposed rule is not considered a significant regulatory

action under section 3(f) of Executive Order 12866 and was not reviewed

by the Office of Management and Budget. The rule is not considered

significant under the regulatory policies and procedures of the

Department of Transportation (44 FR 11034). The economic impact of this

rule is minimal to the extent that the preparation of a regulatory

evaluation is not warranted.

Executive Order 12612

This proposed rule has been analyzed in accordance with the

principles and criteria contained in Executive Order 12612

(``Federalism''). The Federal hazardous materials transportation law

(49 U.S.C. 5101-5127) contains an express preemption provision that

preempts State, local, and Indian tribe requirements on certain covered

subjects. Covered subjects are:

(i) the designation, description, and classification of hazardous

material;

(ii) the packing, repacking, handling, labeling, marking, and

placarding of hazardous material;

(iii) the preparation, execution, and use of shipping documents

pertaining to hazardous material and requirements respecting the

number, content, and placement of such documents;

(iv) the written notification, recording, and reporting of the

unintentional release in transportation of hazardous material; or

(v) the design, manufacturing, fabrication, marking, maintenance,

reconditioning, repairing, or testing of a package or container which

is represented, marked, certified, or sold as qualified for use in the

transportation of hazardous material.

The Federal hazardous materials transportation law provides that if

DOT issues a regulation concerning any of the covered subjects after

November 16, 1990, DOT must determine and publish in the Federal

5125(b)(2). That effective date may not be earlier than the 90th day

following the date of issuance of the final rule and not later than two

years after the date of issuance. This proposed rule deals with the

packaging of compressed gases. Although this proposal does not

contemplate substantive changes, RSPA solicits comments on whether the

proposed rule would have any effect on State, local or Indian tribe

requirements and, if so, the most appropriate effective date of Federal

preemption. Because RSPA lacks discretion in this area, preparation of

a federalism assessment is not warranted.

Regulatory Flexibility Act

I certify that this proposed rule will not have a significant

economic impact on a substantial number of small entities. This

proposed rule does not impose any new requirements on persons subject

to the HMR.

Paperwork Reduction Act

This proposed rule does not propose any new information collection

requirements.

Regulation Identifier Number (RIN)

A regulation identifier number (RIN) is assigned to each regulatory

action listed in the Unified Agenda of Federal Regulations. The

Regulatory Information Service Center publishes the Unified Agenda in

April and October of each year. The RIN number contained in the heading

of this document can be used to cross-reference this action with the

Unified Agenda.

List of Subjects

49 CFR Part 171

Exports, Hazardous materials transportation, Hazardous waste,

Imports, Reporting and recordkeeping requirements.

49 CFR Part 173

Hazardous materials transportation, Packaging and containers,

Radioactive materials, Reporting and recordkeeping requirements,

Uranium.

49 CFR Part 178

Hazardous materials transportation, Packaging and containers,

Reporting and recordkeeping requirements.

In consideration of the foregoing, 49 CFR parts 171, 173, and 178

would be amended to read as follows:

PART 171--GENERAL INFORMATION, REGULATIONS, AND DEFINITIONS

1. The authority citation for Part 171 would continue to read as

follows:

Authority: 49 U.S.C. 5101-5127; 49 CFR part 1.53.

2. In Sec. 171.7(a)(3), in the table, under the entry ``Aluminum

Standards and Data, Seventh Edition, June 1982'', the section reference

``178.65-5'' is revised to read ``178.65''; and under the entry

Compressed Gas Association, Inc., a new entry is added in alpha-

numerical order to read as follows:

Sec. 171.7 Reference material.

* * * * *

(a) * * *

(3) * * *

------------------------------------------------------------------------

49 CFR

Source and name of material reference

------------------------------------------------------------------------

* * * * *

Compressed Gas Association, Inc.,

* * * * *

CGA Pamphlet C-11, Recommended Practices for Inspection of

Compressed Gas Cylinders at Time of Manufacture, 1993...... 178.35

* * * * *

------------------------------------------------------------------------

* * * * *

PART 173--SHIPPERS--GENERAL REQUIREMENTS FOR SHIPMENTS AND

PACKAGINGS

3. The authority citation for Part 173 would continue to read as

follows:

Authority: 49 U.S.C. 5101-5127; 49 CFR part 1.53.

Sec. 173.34 [Amended]

4. In Sec. 173.34, paragraph (h) would be amended by:

a. Removing, in the first sentence, the phrase ``Secs. 178.36-9(a),

178.37-9(a), 178.38-9(a), and 178.40-9(a)'' and replacing it with the

phrase ``Secs. 178.36(e), 178.37(e), 178.38(e), and 178.40(e)''.

b. Removing, in the fourth sentence, the phrase ``Sec. 178.36-9(a),

Sec. 178.37-9(a), Sec. 178.38-9(a), or Sec. 178.40-9(a)'' and replacing

it with the phrase ``Sec. 178.36(e), Sec. 178.37(e), Sec. 178.38(e), or

Sec. 178.40(e)''.

Sec. 173.316 [Amended]

5. In Sec. 173.316, in paragraph (a)(8), the section reference

``178.57- 20(a)(4)'' would be revised to read ``178.35'' and in

paragraph (c)(3)(ii) the section reference ``178.57-20'' would be

revised to read ``178.35''.

PART 178--SPECIFICATIONS FOR PACKAGINGS

6. The authority citation for Part 178 would continue to read as

follows:

Authority: 49 U.S.C. 5101-5127; 49 CFR 1.53.

7. Subpart C of Part 178 would be revised to read as follows:

Subpart C--Specifications for Cylinders

Sec.

178.35 General requirements for specification cylinders.

178.36 Specifications 3A and 3AX seamless steel cylinders.

178.37 Specification 3AA and 3AAX seamless steel cylinders.

[[Page 8330]]

178.38 Specification 3B seamless steel cylinders.

178.39 Specification 3BN seamless nickel cylinders.

178.42 Specification 3E seamless steel cylinders.

178.44 Specification 3HT seamless steel cylinders for aircraft use.

178.45 Specification 3T seamless steel cylinder.

178.46 Specification 3AL seamless aluminum cylinders.

178.47 Specification 4DS welded stainless steel cylinders for

aircraft use.

178.50 Specification 4B welded or brazed steel cylinders.

178.51 Specification 4BA welded or brazed steel cylinders.

178.53 Specification 4D welded steel cylinders for aircraft use.

178.55 Specification 4B240ET welded or brazed cylinders.

178.56 Specification 4AA480 welded steel cylinders.

178.57 Specification 4L welded insulated cylinders.

178.58 Specification 4DA welded steel cylinders for aircraft use.

178.59 Specification 8 steel cylinders with porous fillings for

acetylene.

178.60 Specification 8AL steel cylinders with porous fillings for

acetylene.

178.61 Specification 4BW welded steel cylinders with electric-arc

welded longitudinal seam.

178.65 Specification 39 non-reusable (non-refillable) cylinders.

178.68 Specification 4E welded aluminum cylinders.

Subpart C--Specifications for Cylinders

Sec. 178.35 General requirements for specification cylinders.

(a) Compliance with the requirements of this subpart is required in

all details.

(b) Inspections and analyses. Chemical analyses and tests as

specified must be made within the United States unless otherwise

approved in writing by the Associate Administrator, in accordance with

Sec. 173.300b of this subchapter. Inspections and verifications must be

performed by--

(1) An independent inspection agency approved in writing by the

Associate Administrator, in accordance with Sec. 173.300a of this

subchapter; or

(2) For DOT Specifications 3B, 3BN, 4B, 4BA, 4D (water capacity

less than 1,100 cubic inches), 4B240ET, 4AA480, 4L, 8, 8AL, 4BW, 39

(marked service pressure 900 p.s.i.g. or lower) and 4E manufactured in

the United States, a competent inspector of the manufacturer.

cylinder made is in conformance with the applicable specification.

Except as otherwise specified in the applicable specification, the

inspector shall perform the following:

(1) Inspect all material and reject any not meeting applicable

requirements. For cylinders made by the billet-piercing process,

billets must be inspected and shown to be free from pipe, cracks,

excessive segregation and other injurious defects after parting or,

when applicable, after nick and cold break.

(2) Verify the material of construction meets the requirements of

the applicable specification by--

(i) Making a chemical analysis of each heat of material;

(ii) Obtaining a certified chemical analysis from the material

manufacturer for each heat of material (a ladle analysis is

acceptable); or

(iii) If an analysis is not provided for each heat of material by

the material manufacturer, by making a check analysis of a sample from

each coil, sheet, or tube.

(3) Verify compliance of cylinders with the applicable

specification by--

(i) Verifying identification of material is proper;

(ii) Inspecting the inside of the cylinder before closing in ends;

(iii) Verifying that the heat treatment is proper;

(iv) Obtaining samples for all tests and check chemical analyses;

(v) Witnessing all tests;

(vi) Verify threads by gauge;

(vii) Reporting volumetric capacity and tare weight (see report

form) and minimum thickness of wall noted; and

(viii) Verifying that each cylinder is marked in accordance with

the applicable specification.

(4) Furnish complete test reports required by this subpart to the

maker of the cylinder and, upon request, to the purchaser. The test

report must be retained by the inspector for fifteen years from the

original test date of the cylinder.

(d) Defects. A cylinder may not be constructed of material with

seams, cracks, laminations, or other injurious defects.

(e) Safety devices and protection for valves, safety devices, and

other connections, if applied, must be as required or authorized by the

appropriate specification, and as required in Secs. 173.34 and 173.301

of this subchapter.

(f) Markings. Markings on a DOT Specification cylinder must conform

to applicable requirements.

(1) Each cylinder must be marked with the following information:

(i) The DOT specification marking must appear first, followed

immediately by the service pressure. For example, DOT-3A1800.

(ii) The serial number must be placed just below or immediately

following the DOT specification marking.

(iii) A symbol (letters) must be placed just below, immediately

before or following the serial number. Other variations in sequence of

markings are authorized only when necessitated by a lack of space. The

symbol and numbers must be those of the manufacturer. The symbol must

be registered with the Associate Administrator; duplications are not

authorized.

(iv) The inspector's official mark and date of test (such as 5-95

for May 1995) must be placed near the serial number. This information

must be placed so that dates of subsequent tests can be easily added.

An example of the markings prescribed in this paragraph (f)(1) is as

follows:

DOT-3A1800

1234

AB 5-95

or;

DOT-3A1800-1234-XY

AB 5-95

where:

DOT-3A = specification number

1800 = service pressure

1234 = serial number

xy = symbol of manufacturer

AB = inspector's mark

5-95 = date of test

(2) Additional required marking must be applied to the cylinder as

follows:

(i) The word ``spun'' or ``plug'' must be placed near the DOT

specification marking when an end closure in the finished cylinder has

been welded by the spinning process, or effected by plugging.

(ii) As prescribed in specification 3HT (Sec. 178.44) or 3T

(Sec. 178.45), if applicable.

(3) Marking exceptions.

(i) A DOT 3E cylinder is not required to be marked with the

inspector mark.

(ii) An identifying lot number may be marked on the cylinder in

place of a serial number for cylinders not over 2 inches outside

diameter or for cylinders with a volumetric capacity not exceeding 60

cubic inches. Each lot shall not have over 500 cylinders.

(4) Unless otherwise specified in the applicable specification, the

markings on each cylinder must be stamped plainly and permanently on

the shoulder, top head, or neck.

(5) The size of each marking must be least 0.25 inch or as space

permits.

(6) Other markings are authorized provided they are made in low

stress areas other than the side wall and are not of a size and depth

that will create harmful stress concentrations. Such

[[Page 8331]]

marks may not conflict with any DOT required markings.

(g) Inspector's report. Each inspector shall prepare a report

containing, at a minimum, the applicable information listed in CGA

Pamphlet C-11. Any additional information or markings that are required

by the applicable specification must be shown on the test report. The

signature of the inspector on the reports certifies that the processes

of manufacture and heat treatment of cylinders were observed and found

satisfactory.

(h) Report Retention. The manufacturer of the cylinders shall

retain the reports required by this subpart for 15 years from the

original test date of the cylinder.

Sec. 178.36 Specification 3A and 3AX seamless steel cylinders.

(a) Type size and service pressure. In addition to the requirements

of Sec. 178.35, cylinders must conform to the following:

(1) A DOT-3A cylinder is a seamless steel cylinder with a water

capacity (nominal) not over 1,000 pounds and a service pressure of at

least 150 pounds per square inch.

(2) A DOT-3AX is a seamless stainless steel cylinder with a water

capacity not less than 1,000 pounds and a service pressure of at least

500 pounds per square inch, conforming to the following requirements:

(i) Assuming the cylinder is to be supported horizontally at its

two ends only and to be uniformly loaded over its entire length

consisting of the weight per unit of length of the straight cylindrical

portion filled with water and compressed to the specified test

pressure; the sum of two times the maximum tensile stress in the bottom

fibers due to bending, plus that in the same fibers (longitudinal

stress), due to hydrostatic test may not exceed 80 percent of the

minimum yield strength of the steel at such maximum stress. Wall

thickness must be increased when necessary to meet the requirement.

(ii) To calculate the maximum longitudinal tensile stress due to

bending, the following formula must be used:

S=Mc/I

(iii) To calculate the maximum longitudinal tensile stress due to

hydrostatic test pressure, the following formula must be used:

S=A1P/A2

where:

S = tensile stress-p.s.i.;

M = bending moment-inch pounds (wl\2\)/8;

w = weight per inch of cylinder filled with water;

l = length of cylinder-inches;

c = radius (D)/(2) of cylinder-inches;

I = moment of inertia-0.04909 (D\4\-d\4\) inches fourth;

D = outside diameter-inches;

d = inside diameter-inches;

A1 = internal area in cross section of cylinder-square inches;

A2 = area of metal in cross section of cylinder-square inches;

P = hydrostatic test pressure-p.s.i.

(b) Steel. Open-hearth or electric steel of uniform quality must be

used. Content percent may not exceed the following: Carbon, 0.55;

phosphorous, 0.045; sulphur, 0.050.

suitable method, except that plates and billets for hot-drawn cylinders

must be marked with the heat number.

(d) Manufacture. Cylinders must be manufactured using equipment and

processes adequate to ensure that each cylinder produced conforms to

the requirements of this subpart. No fissure or other defect is

permitted that is likely to weaken the finished cylinder appreciably. A

reasonably smooth and uniform surface finish is required. If not

originally free from such defects, the surface may be machined or

otherwise treated to eliminate these defects. The thickness of the

bottoms of cylinders welded or formed by spinning is, under no

condition, to be less than two times the minimum wall thickness of the

cylindrical shell; such bottom thicknesses must be measured within an

area bounded by a line representing the points of contact between the

cylinder and floor when the cylinder is in a vertical position.

(e) Welding or brazing. Welding or brazing for any purpose

whatsoever is prohibited except as follows:

(1) Welding or brazing is authorized for the attachment of

neckrings and footrings which are non-pressure parts and only to the

tops and bottoms of cylinders having a service pressure of 500 pounds

per square inch or less. Cylinders, neckrings, and footrings must be

made of weldable steel, the carbon content of which may not exceed 0.25

percent except in the case of 4130X steel which may be used with proper

welding procedures.

(2) As permitted in paragraph (d) of this section.

(3) Cylinders used solely in anhydrous ammonia service may have a

\1/2\ inch diameter bar welded within their concave bottoms.

(f) Wall thickness. For cylinders with service pressure less than

900 pounds, the wall stress may not exceed 24,000 pounds per square

inch. A minimum wall thickness of 0.100 inch is required for any

cylinder over 5 inches outside diameter. Wall stress calculation must

be made by using the following formula:

S=[P(1.3D\2\+0.4d\2\)]/(D\2\-d\2\)

where:

S=wall stress in pounds per square inch;

P=minimum test pressure prescribed for water jacket test or 450 pounds

per square inch whichever is the greater;

D=outside diameter in inches;

d=inside diameter in inches.

(g) Heat treatment. The completed cylinder must be uniformly and

properly heat-treated prior to tests.

(h) Openings in cylinders and connections (valves, fuse plugs,

etc.) for those openings. Threads are required on openings.

(1) Threads must be clean cut, even, without checks, and to gauge.

(2) Taper threads, when used, must be of length not less than as

specified for American Standard taper pipe threads.

(3) Straight threads having at least 6 engaged threads are

authorized. Straight threads must have a tight fit and calculated shear

strength of at least 10 times the test pressure of the cylinder.

Gaskets, adequate to prevent leakage, are required.

(i) Hydrostatic test. Each cylinder must successfully withstand a

hydrostatic test, as follows:

(1) The test must be by water-jacket, or other suitable methods,

operated so as to obtain accurate data. The pressure gauge must permit

reading to an accuracy of 1 percent. The expansion gauge must permit

reading of total expansion to an accuracy of either 1 percent or 0.1

cubic centimeter.

(2) Pressure must be maintained for at least 30 seconds and

sufficiently longer to ensure complete expansion. Any internal pressure

applied after heat-treatment and previous to the official test may not

exceed 90 percent of the test pressure. If, due to failure of the test

apparatus the test pressure cannot be maintained the test may be

repeated at a pressure increased by 10 percent or 100 pounds per square

inch, whichever is the lower.

(3) Permanent, volumetric expansion may not exceed 10 percent of

the total volumetric expansion at test pressure.

(4) Each cylinder must be tested to at least 5/3 times service

pressure.

(j) Flattening test. A flattening test must be performed on one

cylinder taken at random out or each lot of 200 or less, by placing the

cylinder between wedge shaped knife edges having a 60 deg. included

angle, rounded to \1/2\-inch radius. The longitudinal axis of the

cylinder must be at a 90-degree angle to

[[Page 8332]]

knife edges during the test. For lots of 30 or less, flattening tests

are authorized to be made on a ring at least 8 inches long cut from

each cylinder and subjected to same heat treatment as the finished

cylinder.

(k) Physical test. A physical test must be conducted to determine

yield strength, tensile strength, elongation, and reduction of area of

material as follows:

(1) The test is required on 2 specimens cut from 1 cylinder taken

at random out of each lot of 200 or less. For lots of 30 or less,

physical tests are authorized to be made on a ring at least 8 inches

long cut from each cylinder and subjected to same heat treatment as the

finished cylinder.

(2) Specimens must conform to the following:

(i) Gauge length of 8 inches with a width of not over 1\1/2\

inches, a gauge length of 2 inches with a width of not over 1\1/2\

inches, or a gauge length of at least 24 times thickness with width not

over 6 times thickness is authorized when cylinder wall is not over \3/

16\ inch thick.

(ii) The specimen, exclusive of grip ends, may not be flattened.

Grip ends may be flattened to within 1 inch of each end of the reduced

section.

(iii) When size of cylinder does not permit securing straight

specimens, the specimens may be taken in any location or direction and

may be straightened or flattened cold, by pressure only, not by blows.

When specimens are so taken and prepared, the inspector's report must

show in connection with record of physical tests detailed information

in regard to such specimens.

(iv) Heating of a specimen for any purpose is not authorized.

(3) The yield strength in tension must be the stress corresponding

to a permanent strain of 0.2 percent of the gauge length. The following

conditions apply:

(i) The yield strength must be determined by either the ``offset''

method or the ``extension under load'' method as prescribed in ASTM

Standard E8-78.

(ii) In using the ``extension under load'' method, the total strain

(or ``extension under load'') corresponding to the stress at which the

0.2-percent permanent strain occurs may be determined with sufficient

accuracy by calculating the elastic extension of the gauge length under

appropriate load and adding thereto 0.2 percent of the gauge length.

Elastic extension calculations must be based on an elastic modulus of

30,000,000. In the event of controversy the entire stress-strain

diagram must be plotted and the yield strength determined from the 0.2

percent offset.

(iii) For the purpose of strain measurement, the initial strain

must be set while the specimen is under a stress of 12,000 pounds per

square inch and the strain indicator reading must be set at the

calculated corresponding strain.

(iv) Cross-head speed of the testing machine may not exceed \1/8\

inch per minute during yield strength determination.

(l) Acceptable results for physical and flattening tests. Either of

the following is an acceptable result:

(1) An elongation at least 40 percent for a 2-inch gauge length or

at least 20 percent in other cases and yield strength not over 73

percent of tensile strength. In this instance, the flattening test is

not required.

(2) An elongation at least 20 percent for a 2-inch gauge length or

10 percent in other cases and a yield strength not over 73 percent of

tensile strength. In this instance, the flattening test is required,

without cracking, to 6 times the wall thickness.

(m) Leakage test. All spun cylinders and plugged cylinders must be

tested for leakage by gas or air pressure after the bottom has been

cleaned and is free from all moisture subject to the following

conditions and limitations:

(1) Pressure, approximately the same as but no less than service

pressure, must be applied to one side of the finished bottom over an

area of at least \1/16\ of the total area of the bottom but not less

than \3/4\ inch in diameter, including the closure, for at least 1

minute, during which time the other side of the bottom exposed to

pressure must be covered with water and closely examined for

indications of leakage. Except as provided in paragraph (n) of this

section, a cylinder that is leaking must be rejected.

(2) A spun cylinder is one in which an end closure in the finished

cylinder has been welded by the spinning process.

(3) A plugged cylinder is one in which a permanent closure in the

bottom of a finished cylinder has been effected by a plug.

(4) As a safety precaution, if the manufacturer elects to make this

test before the hydrostatic test, the manufacturer should design the

test apparatus so that the pressure is applied to the smallest area

practicable, around the point of closure, and so as to use the smallest

possible volume of air or gas.

(n) Rejected cylinders. Reheat treatment is authorized for rejected

cylinders. Subsequent thereto, cylinders must pass all prescribed tests

to be acceptable. Repair by welding or spinning is not authorized. Spun

cylinders rejected under the provisions of paragraph (m) of this

section may be removed from the spun cylinder category by drilling to

remove defective material, tapping and plugging.

Sec. 178.37 Specification 3AA and 3AAX seamless steel cylinders.

(a) Type, size and service pressure. In addition to the

requirements of Sec. 178.35, cylinders must conform to the following:

(1) A DOT-3AA cylinder is a seamless steel cylinder with a water

capacity (nominal) of not over 1,000 pounds and a service pressure of

at least 150 pounds per square inch.

(2) A DOT-3AAX cylinder is a seamless steel cylinder with a water

capacity of not less than 1,000 pounds and a service pressure of at

least 500 pounds per square inch, conforming to the following

requirements:

(i) Assuming the cylinder is to be supported horizontally at its

two ends only and to be uniformly loaded over its entire length

consisting of the weight per unit of length of the straight cylindrical

portion filled with water and compressed to the specified test

pressure; the sum of two times the maximum tensile stress in the bottom

fibers due to bending, plus that in the same fibers (longitudinal

stress), due to hydrostatic test pressure may not exceed 80 percent of

the minimum yield strength of the steel at such maximum stress. Wall

thickness must be increased when necessary to meet the requirement.

(ii) To calculate the maximum tensile stress due to bending, the

following formula must be used:

S=Mc/I

(iii) To calculate the maximum longitudinal tensile stress due to

hydrostatic test pressure, the following formula must be used:

S=A\1\P/A\2\

where:

S=tensile stress-p.s.i.;

M=bending moment-inch pounds (wl\2\)/8;

w=weight per inch of cylinder filled with water;

l=length of cylinder-inches;

c=radius (D)/(2) of cylinder-inches;

I=moment of inertia-0.04909 (D\4\-d\4\) inches fourth;

D=outside diameter-inches;

d=inside diameter-inches;

A\1\=internal area in cross section of cylinder-square inches;

A\2\=area of metal in cross section of cylinder-square inches;

P=hydrostatic test pressure-p.s.i.

(b) Authorized steel. Open-hearth, basic oxygen, or electric steel

of uniform

[[Page 8333]]

quality must be used. A heat of steel made under the specifications in

Table 1 of this paragraph (b), check chemical analysis of which is

slightly out of the specified range, is acceptable, if satisfactory in

all other respects, provided the tolerance shown in Table 2 of this

paragraph (b) are not exceeded. When a carbon-boron steel is used, a

hardenability test must be performed on the first and last ingot of

each heat of steel. The results of this test must be recorded on the

Record of Chemical Analysis of Material for Cylinders required by

Sec. 178.35. This hardness test must be made \5/16\-inch from the

quenched end of the Jominy quench bar and the hardness must be at least

Rc 33 and no more than Rc 53. The following chemical analyses are

authorized:

Table 1.--Authorized Materials

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Intermediate

Designation 4130X (percent) NE-8630 (percent) 9115 (percent) (see 9125 (percent) Carbon-boron manganese

(see Note 1) (see Note 1) Note 1) (see Note 1) (percent) (percent)

--------------------------------------------------------------------------------------------------------------------------------------------------------

Carbon....................... 0.25/0.35.......... 0.28/0.33.......... 0.10/0.20.......... 0.20/0.30......... 0.27-0.37......... 0.40 max.

Manganese.................... 0.40/0.90.......... 0.70/0.90.......... 0.50/0.75.......... 0.50/0.75......... 0.80-1.40......... 1.35/1.65

Phosphorus................... 0.04 max........... 0.04 max........... 0.04 max........... 0.04 max.......... 0.035 max......... 0.04 max.

Sulfur....................... 0.05 max........... 0.04 max........... 0.04 max........... 0.04 max.......... 0.045 max......... 0.05 max.

Silicon...................... 0.15/0.35.......... 0.20/0.35.......... 0.60/0.90.......... 0.60/0.90......... 0.3 max........... 0.10/0.30

Chromium..................... 0.80/1.10.......... 0.40/0.60.......... 0.50/0.65.......... 0.50/0.65......... .................. ..................

Molybdenum................... 0.15/0.25.......... 0.15/0.25.......... ................... .................. .................. ..................

Zirconium.................... ................... ................... 0.05/0.15.......... 0.05/0.15......... .................. ..................

Nickel....................... ................... 0.40/0.70.......... ................... .................. .................. ..................

Boron........................ ................... ................... ................... .................. 0.0005/0.003 ..................

--------------------------------------------------------------------------------------------------------------------------------------------------------

Note 1: This designation may not be restrictive and the commercial steel is limited in analysis as shown in this Table 1.

Table 2.--Check Analysis Tolerances

----------------------------------------------------------------------------------------------------------------

Tolerance (percent) over the

maximum limit or under the

Limit or maximum specified minimum limit

Element (percent) -------------------------------

Under minimum Over maximum

limit limit

----------------------------------------------------------------------------------------------------------------

Carbon........................................ To 0.15 incl.................... 0.02 0.03

Over 0.15 to 0.40 incl.......... .03 .04

Manganese..................................... To 0.60 incl.................... .03 .03

Over 0.60 to 1.15 incl.......... .04 .04

Over 1.15 to 2.50 incl.......... .05 .05

Phosphorus \1\................................ All ranges...................... .............. .01

Sulphur....................................... All ranges...................... .............. .01

Silicon....................................... To 0.30 incl.................... .02 .03

Over 0.30 to 1.00 incl.......... .05 .05

Nickel........................................ To 1.00 incl.................... .03 .03

Chromium...................................... To 0.90 incl.................... .03 .03

0.90 to 2.90 incl............... .05 .05

Molybdenum.................................... To 0.20 incl.................... .01 .01

Over 0.20 to 0.40............... .02 .02

Zirconium..................................... All ranges...................... .01 .05

----------------------------------------------------------------------------------------------------------------

\1\ Rephosphorized steels not subject to check analysis for phosphorus.

suitable method except that plates and billets for hot-drawn cylinders

must be marked with the heat number.

(d) Manufacture. Cylinders must be manufactured using equipment and

processes adequate to ensure that each cylinder produced conforms to

the requirements of this subpart. No fissure or other defects is