TM 1-1500-204-23-2 Figure 4-33.  Repairing High-Pressure Tubing be made of aluminum alloy conforming to Federal Specification WW-T-700/4. NOTE Copper tubing of same outside diameter and wall thickness may be used in oxygen sys- tems only In case of emergency, and should conform to Federal Specification WW-T-799, Type N.  Steel tubing shall not be used be- cause it loses its ductility and becomes brittle at low temperature. (a)  Tubing material.   When replacing a damaged tubing assembly, the same size and material shall be selected.  Where like materials are not available, wall thickness which can be used for various diameters and tubing materials under applicable system pressure are shown in table 4-11.  The following paragraphs explain the use of this table. 1  Explanation of codes.  The following information applies to the code symbols The codes shown in table 4-11 indicate that these sizes are stand- ard. TUBING CODE MATERIAIL SPECIFICATION a Aluminum 5052-0 FED SPEC WW-T-700/4 b Aluminum 2024T FED SPEC WW-T-700/3 c Corrosion- Resistant Steel Annealed MIL-T-8504 d Corrosion- Resistant Steel 1/4 hard MIL-T-6845 2 Minimum burst pressures.  In accord- ance with MIL-H-5440, the following minimum tube burst pressures are required for the noted system pro- cedures: SYSTEM PRESSURE BURST PRESSURE 1,000 4,000 1,500 6,000 3,000 12,000 3  Conversion factors  Following are the conversion factors for the materials in table 4-1 1 and the three system pressures. MATERIAL SYSTEM CONVERSION CODE PRESSURE (PSI) FACTOR a 1,000 1,380 1,500 2,070 3,000 4,140 b 1,000 625 1,500 938 3,000 1,875 c 1,000 533 1,500 800 3,000 1,600 d 1,000 333 1,500 500 3,000 1,000 4-31