OOSC, Part II, Item 1. Brake Systems, h. Air Brake Hose/Tubing (5) Crimped Brake Hose/Tubing as to Restrict Air Flow

The NASI Level I Inspection includes: STEP 17 INSPECT TRAILER FRONT AIR AND ELECTRICAL LINES, Check that lines are not crimped or improperly spliced/repaired. The North American Standard Out-of-Service Criteria (OOSC) describe brake hose/tubing \"crimped in such a manner as to restrict air flow\". *1. BRAKE SYSTEMS, h. Brake Hose/Tubing,(5) Damaged by heat, broken, or crimped in such a manner as to restrict air flow. The issue is when we identify airlines crimped in such a manner as to ?restrict? air flow. How much restriction is needed to meet the out-of-service condition?

Currently NASI inspectors identify crimped or kinked air lines as defects and place out-of-service when meeting the criteria. Some inspectors interpret the "crimped to restrict air flow" statement as any restriction of air flow as out-of-service. Other inspectors may interpret the \"crimped to restrict air flow\" statement as the restriction needs to completely cut off air flow through the line. The application of this item may cause inconsistent carrier/driver enforcement.

The following TMC recommended practice RP 435 seems to answer the question about airline kinks. RP 435 INSTALLATION AND INSPECTION GUIDELINES FOR PNEUMATIC TRACTOR-TRAILER HOOKUP LINES, 3. Air Line Inspection: 3.1?No kinks should exist, as these will restrict airflow. A line should be considered kinked if the diameter of the ?narrow? section is less than 67 percent (2/3) of the diameter of the ?wide? section when both measurements are taken at the same point along the line. The most common location for a kink is at the point where the line is suspended and under the spring at the fitting on the gladhand end. The SAE J1402 for Automotive Air Brake Hose and Hose Assemblies recommended practice for acceptable performance for the minimum inside diameter (ID) of the end fitting or the hose to be not less than 66% of the minimum hose ID was the derivative if I remember correctly. If the manufacture guideline requires 2/3?s of the hose diameter to work properly then it makes sense to apply the same rational to kinks. 7.1 Acceptance Performance Hose or hose assemblies at the time of manufacture shall conform to the following: 7.1.1 END FITTINGS End fittings shall be such as to permit conformance to all portions of this recommended practice. After assembly of the end fittings to the hose, the minimum I.D. of the end fittings or the hose shall not be less than 66% of the minimum hose ID shown in Table 1. All hose assemblies shall pass this requirement prior to conducting any other test in this recommended practice. This Issue/Request for Action proposes to amend the OOSC item for Brake Hose/Tubing by adding \"or kinked\" after crimped and adding the NOTE for clarification. *1. BRAKE SYSTEMS, h. Brake Hose/Tubing, (5) Damaged by heat, broken, or crimped \"or kinked\" in such a manner as to restrict air flow. NOTE: A line should be considered crimped or kinked in such a manner as to restrict air flow if the diameter of the ?narrow? section is less than 67 percent (2/3) of the diameter of the ?wide? section when both measurements are taken at the same point along the line.