Tube assemblies that require paint as a protective finish are described in table 6-8. Titanium or stainless steel tubing does not require primer or paint except in areas of dissimilar metals. Primer or paint on

stainless steel tubing currently installed on naval aircraft need not be removed. The basic reason for this is that cracked or damaged paint systems establish a differential oxygen concentration cell, which may result in tubing corrosion damage. Do not paint interior surfaces of airspeed indicator tubing, oxygen, or other plumbing lines. Tube assemblies located inside of an aircraft are interior tube assemblies. Tube assemblies located outside of an aircraft are exterior tube assemblies. Interior tube assemblies require a protective finish of two coats of zinc chromate, using application techniques as specified in in NA01-1A-509.

Fabricated tube assemblies should be identified before installation or storage. All information from the identification tag of the removed tube assembly should be transferred to the tag on replacement tube assembly. Identify the tube assemblies by ink stamping or stenciling the part number, manu-facturers code, and other required data on tube assemblies. Apply a protective coat of clear varnish over the markings. To aid in the rapid identification of the various tubing systems and operating pressure, each fluid line in the aircraft is identified by bands of paint or strips of tape around the line near each fitting. These identifying media are applied at least once in each compartment. Various other information is also applied to the lines.

Identification tapes are applied to all lines less than 4 inches in diameter except cold lines, hot lines, lines in oily environment, and lines in engine compartments where there is a possibility of the tape being drawn into the engine intake. In these cases, and all others where tapes should not be used, painted identification is applied to the lines.

Identification tape codes indicate the function, contents, hazards, direction of flow, and pressure in the fluid line. These tapes are applied in accordance with MIL-STD-1247C. This military standard was issued to standardize fluid line identification throughout the Department of Defense. Figure 6-17 shows the method of applying these tapes as specified by this standard.

The function of a line is identified by use of a tape, approximately 1 inch wide, upon which word(s), color(s), and geometric symbols are printed. Functional identification markings, as provided in MIL-STD-1247C, are the subject of international standardization agreements. Three-fourths of the total width on the left side of the tape has a code color or colors that indicate one function only per color or colors. The function of the line is printed in English across the colored portion of the tape. Even a non-English-speaking person can troubleshoot or maintain the aircraft if he/she knows the code but cannot read English. The right-hand one-fourth of the functional identification tape contains a geometric design rather than the color(s) or word(s). Figure 6-18 is a listing, in tabular form, of functions and their associated identification media as used on

Figure 6-18.Functional identification type data.

Figure 6-19.Color-coded functional identification tapes.

the tapes Figure 6-19 shows the different tapes used . in identifying tubing. The identification-of-hazards tape shows the hazard associated with the contents of the line. Tapes used to show hazards are approximately 1/2 inch wide, with the abbreviation of the hazard contained in the line printed across the tape. There are four general classes of hazards found in connection with fluid lines. These hazards are outlined in the following text:

Flammable material (FLAM). The hazard marking FLAM is used to identify all materials

Figure 6-19.Color-coded functional identification tapesContinued.

known ordinarily as flammables or com-bustibles. Toxic and poisonous materials (TOXIC). A line identified by the word TOXIC contains materials that are extremely hazardous to life or health.

Anesthetics and harmful materials (AAHM). All materials productive of anesthetic vapors and all liquid chemicals and compounds hazardous to life and property, but not normally productive of dangerous quantities of fumes, or vapors, are in this category. Physically dangerous materials (PHDAN). A line that carries material that is not dangerous within itself, but that is asphyxiating in confined areas or is generally handled in a dangerous physical state of pressure or temperature, is identified by the marking