A connector assembly comprising: a housing having a bore extending therethrough along a longitudinal axis thereof, wherein the housing comprises a main body, a first end, and a second end, wherein the main body comprises an outer wall and internal threads that define an inner surface, wherein the second end comprises the internal threads, wherein the housing further comprises an internal shoulder extending laterally relative to the longitudinal axis, extending between a lower circumferential sealing surface and an interior wall, wherein the lower circumferential sealing surface and an upper circumferential sealing surface are located on each side of the internal threads, wherein the upper sealing surface has a diameter extending approximately to roots of the internal threads, wherein the lower circumferential sealing surface comprising a substantially flat, smooth interior surface that is located below the internal threads in a direction extending orthogonally towards the longitudinal axis of the housing; and a plug comprising external threads, a face section, and sealing surfaces (87, 88) located on an outer circumference of the plug that form annular gaps (94, 95), wherein the external threads are adapted to engage the internal threads of the housing and form the annular gaps (94, 95) when engaged, wherein the face section is adapted to be inserted into the housing and to form a fluid seal with the housing to prevent fluids from flowing through the bore, wherein the face section comprises: a first seal adapted to engage the internal shoulder to form a fluid seal; and a front sealing surface extending around the fluid seal, wherein the front sealing surface is adapted to contact the internal shoulder to form a metal-to-metal fluid seal. a housing having a bore extending therethrough along a longitudinal axis thereof, wherein the housing comprises a main body, a first end, and a second end, wherein the main body comprises an outer wall and internal threads that define an inner surface, wherein the second end comprises the internal threads, wherein the housing further comprises an internal shoulder extending laterally relative to the longitudinal axis, extending between a lower circumferential sealing surface and an interior wall, wherein the lower circumferential sealing surface and an upper circumferential sealing surface are located on each side of the internal threads, wherein the upper sealing surface has a diameter extending approximately to roots of the internal threads, wherein the lower circumferential sealing surface comprising a substantially flat, smooth interior surface that is located below the internal threads in a direction extending orthogonally towards the longitudinal axis of the housing; and a plug comprising external threads, a face section, and sealing surfaces (87, 88) located on an outer circumference of the plug that form annular gaps (94, 95), wherein the external threads are adapted to engage the internal threads of the housing and form the annular gaps (94, 95) when engaged, wherein the face section is adapted to be inserted into the housing and to form a fluid seal with the housing to prevent fluids from flowing through the bore, wherein the face section comprises: a first seal adapted to engage the internal shoulder to form a fluid seal; and a front sealing surface extending around the fluid seal, wherein the front sealing surface is adapted to contact the internal shoulder to form a metal-to-metal fluid seal. a first seal adapted to engage the internal shoulder to form a fluid seal; and a front sealing surface extending around the fluid seal, wherein the front sealing surface is adapted to contact the internal shoulder to form a metal-to-metal fluid seal.