A shoulder ring, for installation in a pipe coupling having tapered internal threads, said shoulder ring comprising: (a) a ring body defining a central opening and having a mill end face, a field end face, a circumferential outer surface extending between said mill end and field end faces, and a circumferential inner surface extending between said mill end and field end faces, with said ring body being of substantially uniform cross-sectional configuration; characterised by: (b) axial retention means associated with the outer surface of the ring, for engagement with an internal threaded surface of the pipe coupling providing the internal threads, said axial retention means comprising a thread element adapted for engagement with the internal threads of the pipe coupling, wherein the thread element has a low stab flank angle and a low thread height, wherein: (b.1) the term "low stab flank angle" means an angle less than would normally be desirable for optimal engagement of said thread element with the internal threads of the pipe coupling; and (b.2) the term "low thread height" means a thread height that is sufficiently smaller than required for normal full mating engagement of the thread element with the internal threads of the pipe coupling; such that the shoulder ring is configured to be installed in the pipe coupling by application of axial force, with the elastic compliance of the shoulder ring causing the shoulder ring to transition in an axial direction from having the crests of the thread element in contact with the crests of the internal threads on the pipe coupling to having the thread element fully engaged with said internal threads. (a) a ring body defining a central opening and having a mill end face, a field end face, a circumferential outer surface extending between said mill end and field end faces, and a circumferential inner surface extending between said mill end and field end faces, with said ring body being of substantially uniform cross-sectional configuration; characterised by: (b) axial retention means associated with the outer surface of the ring, for engagement with an internal threaded surface of the pipe coupling providing the internal threads, said axial retention means comprising a thread element adapted for engagement with the internal threads of the pipe coupling, wherein the thread element has a low stab flank angle and a low thread height, wherein: (b.1) the term "low stab flank angle" means an angle less than would normally be desirable for optimal engagement of said thread element with the internal threads of the pipe coupling; and (b.2) the term "low thread height" means a thread height that is sufficiently smaller than required for normal full mating engagement of the thread element with the internal threads of the pipe coupling; such that the shoulder ring is configured to be installed in the pipe coupling by application of axial force, with the elastic compliance of the shoulder ring causing the shoulder ring to transition in an axial direction from having the crests of the thread element in contact with the crests of the internal threads on the pipe coupling to having the thread element fully engaged with said internal threads. (b.1) the term "low stab flank angle" means an angle less than would normally be desirable for optimal engagement of said thread element with the internal threads of the pipe coupling; and (b.2) the term "low thread height" means a thread height that is sufficiently smaller than required for normal full mating engagement of the thread element with the internal threads of the pipe coupling; such that the shoulder ring is configured to be installed in the pipe coupling by application of axial force, with the elastic compliance of the shoulder ring causing the shoulder ring to transition in an axial direction from having the crests of the thread element in contact with the crests of the internal threads on the pipe coupling to having the thread element fully engaged with said internal threads.