Duct separation restraint apparatus and method

A coupling apparatus for coupling the ends of a pair of ducts carrying a flowing fluid, said apparatus comprising:

• a circumferential clamp ring assembly having first and second clamp rings adapted to be secured in abutting contact;
• an outer clamp ring assembly adapted to be secured over portions of said first and second clamp rings to hold said first and second clamp rings in abutting contact;
• a first catcher member adapted to be fixedly secured to a free edge of a first one of said ducts and fixedly to a first edge of said first clamp ring, said first catcher member including at least one axially extending, flexible catcher finger projecting away from said free edge of said first one of said ducts and generally co-axially with said first one of said ducts;
• and
• a second catcher member adapted to be fixedly secured to a free edge of a second one of said ducts and to said second clamp ring, said second catcher member including a portion spaced apart from said catcher finger by a predetermined distance, and being adapted to engage with said catcher finger in the event of malfunction of one of said circumferential clamp ring assembly and said outer clamp ring assembly to allow a controlled degree of separation of said first and second ducts from one another, in accordance with said predetermined distance, after failure of either one of said circumferential clamp ring assembly and said outer clamp ring assembly;
• and
• wherein said first and second catcher members are disposed so as to reside within said pair of ducts when said ducts are assembled together.

A method for securing edges of first and second pressurized fluid carrying ducts together, comprising:

• fixedly securing a catcher finger component to a first one of said ducts to form an integral portion of said first one of said ducts,
• forming the catcher finger component to include at least one flexible catcher finger extending generally co-axially with, and radially inwardly of, said first one of said ducts;
• fixedly securing a catcher ring component to a second one of said ducts to form an integral portion of said second one of said ducts;
• forming said catcher ring component with a flange portion projecting radially inwardly, relative to said second one of said ducts;
• securing said first and second ducts in longitudinal alignment such that a joint is effectively formed between free edges of said ducts;
• forming said flexible catcher finger with an axial length such that said catcher ring and said flexible catcher finger are spaced apart by a predetermined distance when said ducts are coupled together so that a predetermined degree of axial separation is allowed between said ducts in the event of a failure of an external clamping element securing said two ducts together;
• and
• disposing said portion of said catcher ring, and also said flexible catcher finger, to extend within said ducts.