At Global Valve and Controls we ensure that every valve is tested before it leaves our facility and delivered to your facility. Most manufactuers will only test a small percentage of their valves as it is a time consuming process as you see below. We make sure that every valve whether its a Ball, Gate, Globe, or check valve gets tested. Below is a presentation of how we test our valves. The valves go through the shell test first and then a seat test. We shell test valves to verify the integrity of the body to make sure there are no leaks. Testing the seat verifies positive closure of the valve according to the API specification required for each specific valve.
Source: Valve MD