Press fitting arrangement with a pre-press leak indicator sealing ring

A press fitting arrangement, comprising:

• a tube;
• a press fitting having a bead;
• and
• a sealing ring, the sealing ring having first portions and second portions, wherein the first portions in combination extend along a majority of the sealing ring circumference,
• wherein, prior to housing the sealing ring within the bead of the press fitting and before insertion of the tube into the press fitting, the first portions have an essentially circular cross-section with a diameter (D1), each of the first portions having an outer surface defining an outside diameter (SOD1) of the sealing ring that is greater than an inside diameter (BID) of the bead, and each of the second portions comprises a recess oriented toward an inside of the sealing ring with two projections bordering the recess, wherein each projection bordering the recess of one of the second portions of the sealing ring has a trilobal structure, and wherein each recess is defined by a sealing ring cord section that has a cross-sectional diameter that deviates from the cross-sectional diameter (D1) of the first portions,
• wherein the recess of each second portion has a volume that is defined between the two projections bordering the recess, said volume created by a deviation of the cross-section of the second portion from the essentially circular cross-section of the first portions having the cross-sectional diameter (D1), and wherein the volume of the recess is larger than a total volume of the two projections bordering the recess, wherein the total volume of the two projections bordering the recess is defined by material of the sealing ring having a cross-section that deviates from the essentially circular cross-section of the first portions having the cross-sectional diameter (D1),
• wherein after the sealing ring is housed within the bead of the press fitting and prior to insertion of the tube into the press fitting, each of the first portions further has an inner surface defining an inside diameter (SID1) of the sealing ring that is less than an outside diameter (TOD) of the tube,
• wherein the sealing ring is dimensioned such that, when the tube is inserted into the press fitting, the first portions of the sealing ring housed within the bead of the press fitting are compressed such that the sealing ring remains within the bead and the recess in each of the second portions of the sealing ring provides a gap between the press fitting and the tube, wherein each gap is closable by application of a pressing action to at least one portion of the press fitting which causes a migration of sealing ring material into the sealing ring cord section, said migration of sealing ring material resulting in an expansion of the sealing ring cord section that closes the gap, and
• wherein a cross-section of the trilobal structure of each projection bordering each recess is defined by three circle points around which three circles are arranged to provide two extended portions defined by two of the three circles with substantially equal radii (R1) and one flat portion between said extended portions, the flat portion being on an inside of the sealing ring so as to face the tube inserted in the press fitting as well as one enhanced portion between said extended portions facing the press fitting defined by a third circle of the three circles with a radius (R2).