Steam-tight junction for tubular elements

Claim 1

A male and female junction for first and second tubular elements, said first tubular element having a first end, a stop means on said first tubular element spaced from the said first end, a male junction portion of reduced diameter with a length extending from the first end to said stop means and having an inward taper, the second tubular element having a second end, a female junction portion at the interior of the second element adapted to form a tight seal with said male junction portion comprising, a first annular shoulder at the interior of said second tubular element and located from the second end slightly more than the length of the male junction portion, a tapered frustro conical surface extending from said first annular shoulder toward the second end for a fraction of said length to form a step portion, a second annular shoulder having a small width at the top of the step portion, a tapered frustro conical surface extending from the second annular shoulder to the second end, all of the tapered surfaces having the same slope, a first clearance of only a few thousands of an inch separating the male and female junction portions, whereby the male junction portion is adapted to abut against the step portion of the female junction between the first and second annular shoulder portions and to form a tight seal when the elements expand on being exposed to internal heat or hot vapors, a second clearance larger than said first clearance separating the male and female junction portions in the region between the second annular shoulder and the second end whereby to relieve stresses due to heat expansion and thus prevent cracking of the second tubular element.