Rubber hose and metallic pipe with crimped joints are extensively used in steering system assembly, transmission oil cooler system, brake system etc. to carry hydraulic fluid or lubricants from one place to another. The pipe and rubber hose assembly provides necessary flexibility for complex routing on the vehicle level. Design of hose and pipe assembly for this application are different due to difference in operating pressure and temperature requirement for vehicle application. This paper defines the criteria for design and validation of hose & pipe assembly used to connect automatic transmission with the cooler. Crimped joints are validated for their separation force, leakages, ability to withstand pressure pulsations, burst test etc. Parameters which influence the hose & pipe assembly durability are pipe end flaring dimensions, type of crimping, reinforcement type, its size, material and pattern, rubber material properties, crimping force, effective crimping diameter etc. Minor variations in these design parameters can influence the durability of the assembly. Several trials were carried out to arrive at an optimum design of the hose and pipe assembly for automatic transmission cooling system during development phase. This paper provides guidelines developed based on test results for hose & pipe assembly development. Sensitivity of parameters such as crimping pressure, pipe flaring design, metal cap thickness, effective crimping diameter, crimping type, reinforcement size on durability of hose & pipe assembly has been discussed in detail in this paper. Optimum hose and pipe assembly designed for passenger car automatic transmission cooling system was subjected to test bench and vehicle level test.