Chemical technology, or, Chemistry in its applications to arts and manufactures Volume 2 - Friedrich Ludwig Knapp, Paperback

• Release Date   5/20/2012
• ISBN-13   9781236335692 | 978-1-236-33569-2
• ISBN   1236335694 | 1-236-33569-4
• Format   Paperback
• Author(s)   Friedrich Ludwig Knapp
• This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1895 Excerpt: ...has to be resorted to. This consists in the use of an expanding reamer, Fig. 99, by means of which the well may be drilled of a size slightly greater than the external diameter of the casing. The instrument is provided with a pair of pivoted wings, or dogs, a a, which are forced outwards into the position shown in B, by the pressure of a powerful helical spring (enclosed in the tubular rod), exerted through the medium of the sliding collar, b. When the under-reamer is to be inserted in the casing, the sliding collar is raised, as shown in A, and retained in that position by small wedges, c c. The wings, or dogs, then lie flat against the rod, as shown in A. A few strokes of the tools dislodge the wedges, the dogs at once spring out into the positions.shown in B, and the well is "reamed "to a diameter admitting of the descent of the casing. The Canadian system of drilling has almost entirely superseded the free-fall system in Galieia. It is undeniably more rapid, and, as it is carried out with far less concussion, the risk of caving is reduced. The rate at which the blows of the chisel are delivered with Canadian tools varies with the character of the ground. sometimes as many as 70 strokes a minute may be given, but the number usually ranges between 40 and 60. It is usual to case the upper part of the well with what is known as riveted casing. This consists of tubing made of sheet-iron, with riveted seams, and is not water-tight. To shut off the water, artesian casing, consisting of wrought-iron lap-welded tubing, with screwed joints, is employed. The casing is added in successive lengths during the drilling of the well, until it cannot be forced down any lower. The diameter of the well is then reduced, and a smaller casing used. In this way, a co...