Before you can get certification in welding pipes you have to be certified all position 6011 7018 and wire feed then you can go to any company that has a certified welder that can do your certification and can charge you to take the pipe test, the pipe test is done using 6011 as a root weld then 7018 as the finish weld, the pipe will be at a 60 degree angle when your welding it, and once you completed the weld they grade it on appearance then cut it and do a bend test on the weld, they do that by cutting the pipe you welded then bend the weld 180 degree's from it's Original position, if there are less than 1/32 of a crack over the piece you weld you will get your certification in pipe welding, if not you can take a class at most community colleges, and Most community colleges offer this test for a fee. As for any other type weld you are certified by the company that does the welding. They normally have one person who can certify AWS and give you a certificate for pipe, each type of weld is different, like stainless tig mig aluminum Tungsten and so on hope this helps.