173.34 49 CFR Ch. I (101 01 Edition) - Safe Air Systems

1 42649 cfr ch . I (10 1 01 edition ) Qualification, maintenanceand use of cylinders.(a) General qualification for use of cyl-inders. (See through for re-quirements applying to all shipments.)(1) No person may charge or fill a cyl-inder unless it is as specified in thispart and part 178 of this subchapter. Acylinder that leaks, is bulged, has de-fective valves or safety devices, bearsevidence of physical abuse, fire or heatdamage, or detrimental rusting or cor-rosion, must not be used unless it isproperly repaired and requalified asprescribed in these regulations.(2) When cylinders with a markedpressure limit are prescribed, othercylinders made under the same speci-fication but with a higher marked serv-ice pressure limit are authorized.

2 Forexample, cylinders marked DOT 4B500may be used where DOT 4B300 is speci-fied.(b) Grandfather clause. A cylinder indomestic use previous to the date uponwhich the specification therefor wasfirst made effective in these regula-tions may be used if the cylinder hasbeen properly tested and otherwisecomplies with the requirements appli-cable for the gas with which it ischarged.(c) Cylinder marking. Each requiredmarking on a cylinder must be main-tained so that it is legible. Retestmarkings and original markings whichare becoming illegible may be repro-duced by stamping on a metal platewhich must be permanently secured tothe cylinder.

3 (1) Additional information not affect-ing the markings prescribed in the ap-plicable cylinder specification may beplaced on the cylinder. No indentationmay be made in the sidewall of the cyl-inder unless specifically permitted inthe applicable specification.(2) When the space originally pro-vided for dates of subsequent retestsbecomes filled, the stamping of addi-tional test dates into the external sur-face of the footring of a cylinder is au-thorized.(3) Except for marked service pres-sure, markings required on cylindersmay not be altered or removed. Themarked service pressure may bechanged only upon application to theAssociate Administrator and receipt ofwritten instructions as to the proce-dure to be followed.

4 A service pressurechange is not authorized for a cylinderwhich fails to pass the prescribed peri-odic hydrostatic retest, unless it is re-heat treated and requalified in accord-ance with this section.(d) Pressure relief device Systems . Noperson may offer a cylinder chargedwith a compressed gas for transpor-tation in commerce unless the cylinderis equipped with one or more pressurerelief devices sized and selected as totype, location, and quantity and testedin accordance with CGA Pamphlet S (compliance with paragraph CGA Pamphlet S is not required).The pressure relief device system mustbe capable of preventing rupture of thenormally charged cylinder when sub-jected to a fire test conducted in ac-cordance with CGA Pamphlet C 14, orin the case of an acetylene cylinder,CGA Pamphlet C 12.

5 Cylinders shallnot be shipped with leaking safety re-lief devices. Safety relief devices mustbe tested for leaks before the chargedcylinder is shipped from the cylinderfilling plant; it is expressly forbiddento repair leaking fuse plug devices,where leak is through the fusible metalor between the fusible metal and theopening in the plug body, (except by re-moval of the device and replacement ofthe fusible metal.) Exceptions are asfollows:(1) Except as provided in paragraphs(d)(1) (i) through (iii) of this section, apressure relief device is not required ona cylinder 12 inches or less in length,exclusive of neck, and 41 2inches or lessin outside diameter.

6 (i) A pressure relief device is requiredon a specification 9, 39 ( of thissubchapter), 40, or 41 cylinder. A metalpressure relief valve is required on aspecification 39 cylinder used for a liq-uefied flammable gas. A fusible pres-sure relief device is not authorized on aspecification 39 cylinder containing aliquefied compressed gas.(ii) A pressure relief device is re-quired on a cylinder charged with a liq-uefied gas for which this part requiresa service pressure of 1800 psig or high-er.(iii) A pressure relief device is re-quired on a cylinder charged with aVerDate 11<MAY>2000 11:29 Dec 13, 2001 Jkt 194201 PO 00000 Frm 00426 Fmt 8010 Sfmt 8010 Y:\SGML\ pfrm01 PsN: 194201T427 Research and Special Programs Admin.

7 , DOT gas to a pressure of 1,800psig or higher at 70 F.(2) Except for a specification 39 cyl-inder and a cylinder used for acetylenein solution, a pressure relief device isnot required on a cylinder charged witha nonliquefied gas under pressure of 300psig or less at 70 F.(3) A pressure relief device is prohib-ited on a cylinder charged with a Divi-sion or Division material in Haz-ard Zone A.(4) A pressure relief device is prohib-ited on a cylinder charged with fluo-rine.(5) A pressure relief device is not re-quired on a cylinder charged withmethyl mercaptan; with mono-, di-, ortrimethylamine, anhydrous; with notover 10 pounds of nitrosyl chloride; orwith less than 165 pounds of anhydrousammonia.

8 (6) Pressure relief devices, if used,must be in the vapor space of cylinderscontaining pyrophoric liquids, inor-ganic or organic, , covered by (e) Periodic qualification and markingof cylinders. Each cylinder that be-comes due for periodic retest as speci-fied in the following table must be re-tested and marked in conformancewith the requirements of this para-graph (e):RETEST ANDINSPECTION OFCYLINDERS1 Specification under which cylinder wasmade2 Minimum retest pressure ( )3 Retest period(years)DOT 3 .. 3,000 psig .. 5 DOT 3A, 3AA .. 5/3 times service pressure, except non-corrosive service (see (e)(13)).5, 10, or 12 (see (e)(14),(e)(12), (e)(16),and (e)(19))DOT 3AL.

9 5/3 times service pressure .. 5 or 12 (see (e)(19))DOT 3AX, 3 AAX .. 5/3 times service pressure .. 53B, 3BN .. 2 times service pressure (see (e)(13)) .. 5 or 10 (see (e)(12))3C .. Retest not .. 5/3 times service pressure .. 53E .. Retest not .. 5/3 times service pressure .. 3 (see (e)(15))3T .. 5/3 times service pressure .. 54 .. 700 psig .. 104A .. 5/3 times service pressure (see (e)(13)) .. 5 or 10 (see (e)(12))4AA480 .. 2 times service pressure (see (e)(13)) .. 5 or 10 (see (e)(14))4B, 4BA, 4BW, 4B 240ET .. 2 times service pressure, except non-corrosive service (see (e)(13)).5, 10 or 12 (see (e)(11),(e)(12) and(e)(19))4C.

10 Retest not , 4DA, 4DS .. 2 times service pressure .. 5 DOT 4E .. 2 times service pressure, except non-corrosive service (see (e)(13)).54L .. Retest not , 8AL .. 10 or 20 (see (e)(18))DOT 9 .. 400 psig (maximum 600 psig) .. 525 .. 500 .. 526 for filling at over 450 .. 5/3 times service pressure .. 526 for filling at 450 psig and below .. 2 times service pressure, except non-corrosive service (see (e)(13)).5 or 10 (see (e)(11))33 .. 800 psig .. 538 .. 500 psig .. 5 Exemption cylinder .. See current exemption .. See current exemp-tionForeign cylinder (see (j) for re-strictions on use) marked on the cylinder, but not less than 5/3 of any serv-ice or working pressure cylinder not exceeding two inches outside diameter and less than two feet in length is excepted from hydrostatic cylinder in chlorine or sulfur dioxide service made before April 20, 1915, must be retested at 500 cylinders not marked with a service pressure, see (e)(1).