A seal sub system for the connection of fluid lines, including first and second fluid lines, each including a terminal end with an inner diameter. A seal sub includes an inner channel and first and second pin ends, one pin end removably insertable in the fluid line terminal end with the other pin end extending from the fluid line terminal end. A seal forms a seal between the seal sub and the inner diameter of the first fluid line terminal end. The extending pin end is configured to be inserted into the terminal end of the second fluid line to establish a sealed fluid connection between the first and second fluid lines.