MIL-DTL-22606D(SH)
3.3.1 Internal drain assemblies. Service A flasks intended for inclined installation beyond 45 degrees from
vertical shall have an internal drain installed in accordance with figure 7 and the requirements specified (see 6.2).
The internal drain tube shall be fabricated of ASTM A269 Grade TP 304. The open end of the drain tube shall be
located at the lowest point to facilitate optimal drainage.
3.3.2 Fabrication welds. Welding shall be in accordance with S9074-AR-GIB-010/278. Seal welding
procedures shall be approved by contracting activities (see figure 11 for a typical seal weld). Fabrication welds and
weld repairs shall be inspected as specified in 4.3.4.1. Multi-pass fabrication and attachment welds, other than seal
welds, shall have a separate root pass inspection. Weld acceptance shall be in accordance with MIL-STD-2035.
3.3.3 Heat treatment. After completion of hot forming operations and all welding on the flask body other than
seal welding, the flask shall be heated above the upper critical transformation temperature and quenched in a
suitable medium and tempered to achieve the required mechanical properties specified in table II. The minimum
tempering temperature shall be 1100 °F. After heat treatment, welds shall be examined as specified in 4.3.4.1. If a
weld joint repair is made within inch of the flask body, the flask shall again be fully heat-treated, and all welds re-
examined as specified in 4.3.4.1.
3.3.4 Threads. Threads shall be Unified National Threads in accordance with FED-STD-H28 (see figures 3, 4,
3.3.6 O-rings and backup rings. O-rings and backup rings shall be in accordance with figure 9. O-rings and
backup rings shall be installed in end plugs as shown on figure 8 View A. O-rings and backup rings shall not be
installed in seal welded plugs.
3.3.7 Inerting caps. Inerting caps shall be in accordance with figure 13.
3.4 Pressure integrity.
3.4.1 Flasks. After final heat treatment, but prior to final cleaning and painting, each flask shall pass the test
specified in 4.3.3.1. Flasks shall meet the acceptance criteria specified in MIL-STD-2035 when examined as
specified in 4.3.4.2. Flask indications and loss of back reflections shall not exceed that specified in 4.3.4.3 when
examined as specified in 4.3.4.3.
3.4.2 End plugs. After final heat treatment, but prior to final cleaning and painting, end plugs shall not leak nor
show any signs of leakage when tested as specified in 4.3.3.3. Plugs which pass the hydrostatic test shall be marked
with the letter "H" as specified in 3.11.2.d.
3.5 Surface preparation prior to coating. Flask interior and exterior surfaces shall be free of mill scale, rust,
manufacturing oils, and other dirt or debris that would interfere with the application of a protective coating. Flask
surfaces shall be steam cleaned, dried, grit blasted, and vacuumed to remove all unwanted contamination in
accordance with 3.5.1 and 3.5.2. Surface imperfections, such as round-bottom pits, scores, and gouges 1/16 inch or
less in depth are acceptable, unless the depth of the imperfection violates the minimum wall thickness specified in
the applicable table I or IV. The cylindrical section and formed ends and necks shall be free of surface cracks.
3.5.1 Blasting. Flask surfaces shall be abrasive blasted to a near-white finish in accordance with SSPC-SP
10/NACE No. 2. The abrasive and particle size shall be selected by the manufacturer to produce surface finishes
suitable for the application of the protective coatings specified herein. The abrasive debris shall be removed by
vacuuming or other suitable means. Threads shall be protected from damage during blasting operations.
3.5.2 Contamination. Cleaned flasks shall be oil-free when tested as specified in 4.2.3. Flasks showing any
trace of oil contamination shall be recleaned as specified in 3.5.1. Flasks shall be recleaned until the ultraviolet light
examination shows no oil contamination. If turning or rust bloom occurs, flasks shall be reblasted to near-white
finish and retested with ultraviolet light until the UV light examination of 4.2.3 shows no contamination.
3.5.3 Drying. Flasks shall be thoroughly dried prior to painting or inerting.
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