There are to many to list I have a binder full of them every where you go there seems to be another one that you can't live without, I find that the biggest challenge keeping up with the ones yhat make you money and the ones that look good in the log book. Aswell it will depend on the area in which you work ie- structural,pipe pressure, ship building,underwater, etc to name a few. There are also many bodies AWS,CWB ASME,ABSA,Loyds etc,etc etc everybody wants their pound of flesh.