We are welding 14 ga stainless steel tanks and we use diesel fuel to check for leaks in the welds. We spray the outside of the weld with the diesel and let it sit for a set time then go inside and look for any diesel coming thru. One of our customers is asking about this test and is hoping we can give him some documentation on this procedure. I was wondering if anyone has ever seen anything written about this test, if so where? thanks