(a) General. Unless otherwise provided in this subpart, tanks designed to be removed from cars for filling and emptying and tanks built to a Class DOT 107A specification and their safety relief devices must be retested periodically as specified in Retest Table 1 of paragraph (b)(5) of this section. Retests may be made at any time during the calendar year the retest falls due.
(b) Pressure test.
(1) Each tank must be subjected to the specified hydrostatic pressure and its permanent expansion determined. Pressure must be maintained for 30 seconds and for as long as necessary to secure complete expansion of the tank. Before testing, the pressure gauge must be shown to be accurate within 1 percent at test measure. The expansion gauge must be shown to be accurate, at test pressure, to within 1 percent. Expansion must be recorded in cubic cm. Permanent volumetric expansion may not exceed 10 percent of total volumetric expansion at test pressure and the tank must not leak or show evidence of distress.
(2) Each tank, except tanks built to specification DOT 107A, must also be subjected to interior air pressure test of at least 100 psig under conditions favorable to detection of any leakage. No leaks may appear.
(3) Safety relief valves must be retested by air or gas, must start-to-discharge at or below the prescribed pressure and must be vapor tight at or above the prescribed pressure.
(4) Rupture discs and fusible plugs must be removed from the tank and visually inspected.
(5) Tanks must be retested as specified in Retest Table 1 of this paragraph (b)(5), and before returning to service after repairs involving welding or heat treatment:
Retest Table 1
| Specification | Retest interval - years | Minimum Retest pressure - psig |
Pressure relief valve pressure - psig |
|||
|---|---|---|---|---|---|---|
| Tank | Pressure relief devicesd | Tank hydrostatic expansionc |
Tank air test | Start-to- discharge |
Vapor tight | |
| DOT 27 | 5 | 2 | 500 | 100 | 375 | 300 |
| 106A500 | 5 | 2 | 500 | 100 | 375 | 300 |
| 106A500X | 5 | 2 | 500 | 100 | 375 | 300 |
| 106A800 | 5 | 2 | 800 | 100 | 600 | 480 |
| 106A800X | 5 | 2 | 800 | 100 | 600 | 480 |
| 106A800NCI | 5 | 2 | 800 | 100 | 600 | 480 |
| 107A * * * * | d5 | a2 | (b) | None | None | None |
| 110A500-W | 5 | 2 | 500 | 100 | 375 | 300 |
| 110A600-W | 5 | 2 | 600 | 100 | 500 | 360 |
| 110A800-W | 5 | 2 | 800 | 100 | 600 | 480 |
| 110A1000-W | 5 | 2 | 1,000 | 100 | 750 | 600 |
| BE-27 | 5 | 2 | 500 | 100 | 375 | 300 |
(6) The month and year of test, followed by a “V” if visually inspected as described in paragraph (c) of this section, must be plainly and permanently stamped into the metal of one head or chime of each tank with successful test results; for example, 01-90 for January 1990. On DOT 107A**** tanks, the date must be stamped into the metal of the marked end, except that if all tanks mounted on a car have been tested, the date may be stamped into the metal of a plate permanently applied to the bulkhead on the “A” end of the car. Dates of previous tests and all prescribed markings must be kept legible.
(c) Visual inspection. Tanks of Class DOT 106A and DOT 110A-W specifications (§§ 179.300 and 179.301 of this subchapter) used exclusively for transporting fluorinated hydrocarbons and mixtures thereof, and that are free from corroding components, may be given a periodic complete internal and external visual inspection in place of the periodic hydrostatic retest. Visual inspections shall be made only by competent persons. The tank must be accepted or rejected in accordance with the criteria in CGA C-6 (IBR, see § 171.7 of this subchapter).
(d) Written records. The results of the pressure test and visual inspection must be recorded on a suitable data sheet. Completed copies of these reports must be retained by the owner and by the person performing the pressure test and visual inspection as long as the tank is in service. The information to be recorded and checked on these data sheets are: Date of test and inspection; DOT specification number; tank identification (registered symbol and serial number, date of manufacture and ownership symbol); type of protective coating (painted, etc., and statement as to need for refinishing or recoating); conditions checked (leakage, corrosion, gouges, dents or digs, broken or damaged chime or protective ring, fire, fire damage, internal condition); test pressure; results of tests; and disposition of tank (returned to service, returned to manufacturer for repair, or scrapped); and identification of the person conducting the retest or inspection.
[Amdt. 180-8, 60 FR 49079, Sept. 21, 1995, as amended by Amdt. 179-50, 61 FR 33257, June 26, 1996; 65 FR 58633, Sept. 29, 2000; 66 FR 45187, 45392, Aug. 28, 2001; 68 FR 75765, Dec. 31, 2003]