Abstract: A pipe union assembly with embodiments which are capable of use over a very wide temperature range and which may be cycled through temperatures varying widely from the ambient assembly temperature and also over a wide range of pressures without the need to be retightened. Embodiments of the invention also include structures to automatically check the flow of fluids from the components of the pipe union upon disassembly of the union. The pipe union generally comprises one or more fitting members and a sealing member. The sealing member receives a ridge formed on each fitting member in a sealing fashion. One or more external sleeves hold the fitting member and the sealing member in sealing engagement. The materials from which each fitting member and sealing member are fabricated may be chosen so as to exhibit the proper hardness characteristics and thermal expansion coefficients. A compensating washer is also provided to increase compensation for thermal contractions at low temperatures.

Abstract: A pipe union assembly with embodiments which are capable of use over a very wide temperature range and which may be cycled through temperatures varying widely from the ambient assembly temperature and also over a wide range of pressures without the need to be retightened. Embodiments of the invention also include structures to automatically check the flow of fluids from the components of the pipe union upon disassembly of the union. The pipe union generally comprises one or more fitting members and a sealing member. The sealing member receives a ridge formed on each fitting member in a sealing fashion. One or more external sleeves hold the fitting member and the sealing member in sealing engagement. The materials from which each fitting member and sealing member are fabricated may be chosen so as to exhibit the proper hardness characteristics and thermal expansion coefficients. A compensating washer is also provided to increase compensation for thermal contractions at low temperatures.