TM 1-1500-204-23-2 4  Use of table.  For example, the mini- mum standard wall thickness must be determined for a 1/2 Inch outside diameter (OD), 1/4 hard corrosion- resistant steel tube for a 3,000 psi system.  From the above paragraph, the conversion factor is 1000.  From table 4-1 1, the nearest value must be found that applies to this material This value is 1,120.  This indicates a 1/2 inch OD x 0.028 inch tube, which is a standard size indicated by the code d for 1/4 hard corrosion-resistant steel. 5  Burst pressure.  Taking any value from the table, it is easy to determine the actual burst pres- sure for a tube The following factors are multiplied by the pressure values shown In table 4-11 to produce the actual burst pressure MATERIAL BURST PRESSURE CODE FACTOR a 2.9 b 6.4 c 7.5 d 1.2 For example, the system pressure producing 10,000 psi stress on the wall of a 1/4 Inch OD x 0.012 annealed corrosion-resistant steel tube is 960 If the system pres- sure is 1,500 psi, the minimum burst pressure is 6,000. Multiplying 960 by the burst pressure factor of 7.5 for this material, the actual burst pressure is 7,100 psi, well above the minimum of 6,000 required for this system. (b) Layout.  A piece of tubing approximately 10 percent longer than length of tubing to be replaced should be cut.  After required bends have been made, new tubing may be 1/2 to 2 inches longer than old tubing Allowances should be made for flaring opera- tin.  The amount of tubing in excess of amount required to flare tube should be cut off. NOTE After cutting, bending, and flaring opera- tins, oxygen tubing assemblies should be cleaned in accordance with paragraph 4-2g (2) d.  Template.  A path should not be selected that requires no bends unless original tubing had a path with no bends A section of tubing cannot be cut and flared accurately enough to be Installed without bends and still avoid initial mechanical strain on tubing except In straight runs not having rigid connections on each end. A fluid line is a mechanical part when installed, and Is sensitive to vibration; therefore, direct, straight-line con- nektons shall never be made between two solid fixed attachment points, as bends allow tubing to expand and contract under temperature differences.  All bends shall be started a reasonable distance from fittings, so sleeve and nut can be slipped back along tubing for inspection. This will also prevent tubing from binding against sleeve Tubing assemblies shall be formed prior to in- stallation so it will not be necessary to pull assembly into alignment by use of coupling nut If old tubing is intact and the bends have not been changed, It may be used as a template.  If rerouting is required and a new template must be made, proceed as follows: 1 Place material selected for use as a template into one of the fittings where tube is to be connected. 2  Form necessary bends In template. 3  Remove template and use pattern to bend new tube 4 Select path with least total degrees bend.  This reduces flow loss and simplifies bending. 5  Use path, if possible, with all bends In same plane. 6  Lay out path which provides for either brackets or clamps to be used as supports at intervals not greater than those given In table 4-12. 4-5.  Flexible Hose Assemblies.  Flexible hose is used In aircraft plumbing to connect moving parts with stationary parts in locations subject to vibration or where a great amount of flexibility is needed.  It can also serve as a connector In metal tubing systems WARNING Do not use flexible hose and hose as- semblies in oxygen systems, as they readily absorb grease and oil.  Failure to comply may result in damage to aircraft of Injury to per- sonnel a.  Identification of Flexible Hose.  Aircraft hose or hose assemblies can be readily identified as to age and 4-32