... load,reliable seal,etc., The valve on the X-mass tree adopts a hidden bar,namely a ... switching torque,simple on-line maintenance,etc.The X-mass tree of the integral type wellhead adopts ... seal,thereby having the characteristics of reliable seal,strong anti-corrosion property,etc.,the tubing hanger extending ... the pipe columns of the double-pipe integral X-mass tree guarantees the two oil pipes to ...