This paper presents a systematic procedure for design and evaluation of snap fit for Quadruple System Protection Valve (QSPV) piston assembly. The QSPV piston is assembled with housing by means of snap joint. Snap joints are a very simple, economical and rapid way of joining two different components. All types of snap joints have in common the principle that a protruding part of one component, e.g., a hook, stud or bead is deflected briefly during the joining operation and catches in a depression (undercut) in the mating component. After the joining operation, the snap-fit features should return to a stress-free condition. The joint may be separable or inseparable depending on the shape of the undercut; the force required to separate the components varies greatly according to the design. It is particularly important to bear the following factors in mind when designing snap joints: Mechanical load during the assembly operation and force required for assembly.