You've got several issues involved there, and it's not clear exactly where you're at.
First off, somebody's got to decide what pressure the thing ought to handle. For containing high-pressure chemical reactions, especially for testing those reactions, that will NOT be a simple question. You can't just say "This is ultra-strong", fill it full of gunpowder and set it off. That may be a chemical engineering question, come to think of it.
Next, assuming you can ascertain exactly what pressure rating is required, look into the codes required. Specifically, there is a Section VIII Division 3 for high-pressure that might be applicable. It would be worthwhile to have somebody that is very familiar with the design of high-pressure vessels going through the design. If you expect to sell this internationally, you may want to look into other codes as well.
Thirdly, the PE end of things will probably take care of itself. If you have people knowledgeable on the first two items, you'll probably also have your PEs. Also note that in many cases, design of a manufactured item is exempt from PE requirements. But, I'm thinking Division II and maybe Division III require a PE for design- perhaps some others can confirm.
On a side note- this video is very informative:
If I remember right, one of the issues was that the products reacted faster than anticipated as heat and temperature increased, and they weren't prepared for those conditions.