The shape of a seal is certainly an important aspect. For example, if you have a U-cup seal in a piston, you want to use U-cup seals as well unless the customer’s specifying that you change it—but you may have to change the piston in that case as well. The shape is important. In those kinds of occasions, seals can be interchangeable but the other part is you have to consider chemical compatibility. You have to know what your customer’s application is if you’re building a cylinder or if you’re specifying one from new, you have to know that if they’re using some kind of advanced synthetic fluid like Skydrol, it’s not compatible with all types of seals … so you need to find one with a composition that is resistant to Skydrol, for example.
For shape, yes, you could use any kind of seal when it comes to shape but the composition, that has to be specific to the application.