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.

A two － dimensional axisymmetric model of friction hydro pillar processing （FHPP） was established base on
Gambit software ．Using the commercial computational fluid dynamics software Fluent ， the numerical simulation of plastic
metal flow pattern was carried out in steady phase of FHPP ．While keeping the other parameters constantly during the process
of numerical simulation ，the velocity field and static pressure field distribution change of ideal metal plastic fluid during the
forming process were analyzed by changing only one critical parameter respectively ，such as the radial clearance between metal
stud and the base hole ，the material viscosity ，the rotary speed of metal stud ，the feed rate of metal stud and the bottom shape
of the base hole ．The result show that the static pressure distribution of plastic metal is affected remarkably by the feed rate （i ．
e ．the axial force） and the material viscosity of metal stud ，and has little to do with the rotary speed and the radial clearance ．
Although the feed rate and the radial clearance have little influence on the velocity distribution of plastic metal ，the effect of
rotary speed is relatively remarkable ，especially for the material neighboring to the wall of the velocity inlet and nearby the
metal stud ．The flow condition of the plastic metal material can be improved by changing the bottom shape of the base hole ，
which can also reveal the reason why there exist some defects at the bottom of the hole ．The above － mentioned research can
provide some guidance to the future experimental study adopting appropriate parametric combination ，and can also lay solid
foundation for the future numerical simulation by thermo － mechanical coupling ．

aking the surface-contact model between rigid flat punch and elastic half-space as the research subject, and through comparing the results of analytical solution and numerical simulation by the finite element method (FEM) software MSC.Marc, it is determined that the non-uniform meshing method and the third grade FEM calculation are reliable as to the surface-contact problem with definite contact area. For the most fundamental surface-contact problem involved with friction hydro pillar processing in friction stitch welding, the normal stress on the contact surface increases quadratically from center to the marginal side. The diameter of the metal stud and the applied external load has more influence to the distribution of normal stress on the contact surface, while the influence of radial clearance, the material combination between the metal stud and the predrilled hole are relatively small.

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.