Jumper spools with connectors are widely used in subsea devices installations during offshore oil and gas fields exploration, and can be operated by horizontal tie-in system or vertical tie-in system. Mechanical collet connector, hydraulic collet connector, and clamp connector are the most common selection in subsea jumper spools connection. Mechanical collet connector is compactive, and leaves no hydraulic components subsea, but connector actuation tools is needed in operation. Hydraulic collet connector is operated directly from the ROV, and with no need for a dedicated actuating tool. Clamp connectors consist of a two piece segmented clamp design and are particularly well suited for larger bore, lower pressure horizontal connection applications. Different connector types and different tie-in manners demand different installation process and different tools. Diameter, tie-in manner, and tools should be considered carefully in the connetor  selection of jumper spool.

he hyperbaric welding test chamber and the automatic GTAW machine were developed for high air ambient pressures. The arc static characteristics curves were tested under 0.1~0.7 MPa air ambient pressures, and the mathematical model of GTAW between arc voltage and parameters such as air ambient pressure, arc length, and current, was created. Based on arc static characteristics and the arc voltage mathematical model, main parameters of the automatic GTAW machine and the welding power were set, then typical position free forming joints of 16Mn steel plate under 0.1~0.7 MPa were manufactured, which were classified as class A in AWS D3.6M: 1999.