. Bulletin . emand, are surprised that this oldmistake continues to be common inmany sections of the country may be said without qualificationthat pipe having eight threads to theinch is not suited to work requiringlong and heavy strings of casing. Adequate tests and comparisonslong ago eliminated S-thread pipefrom practical consideration for usein territory where it must enduresevere stress. The superiority of10-thread pipe has been demonstratedso conclusively that very little 8-thread pipe will nqw be found, evenwhere it was at one time the morepopular. Usage has demonstratedthat t
. Bulletin . emand, are surprised that this oldmistake continues to be common inmany sections of the country may be said without qualificationthat pipe having eight threads to theinch is not suited to work requiringlong and heavy strings of casing. Adequate tests and comparisonslong ago eliminated S-thread pipefrom practical consideration for usein territory where it must enduresevere stress. The superiority of10-thread pipe has been demonstratedso conclusively that very little 8-thread pipe will nqw be found, evenwhere it was at one time the morepopular. Usage has demonstratedthat the S-thread pipe lacks strength,owing to the deeper cut required forthe thread. It was found that thepipe often broke in the thread when figure of stringing casing blocks , . i . for the use of seven lines. subjected to strain. Besides, the 10- thread pipe proved more consistently water-tight and less liable toadmit particles of sand and grit, which would bind the thread anddestroy it in 14 CASING TROUBLES AND FISHING METHODS. Hence it is demonstrated that only in exceptional circumstancescan 8-thread pipe be used to advantage in cable-tool drilling, or per-haps in places where the small amount of pipe required makes thesize of the thread unworthy of much consideration. STRETCHING OF CASING AFTER LANDING. After a string of pipe is landed the pipe should be lifted and theweight supported at the top on a set of clamps. The object in doingthis is to relieve the weight on the lower joints and take up thestretch, so that the pipe will hang taut and rigid in the hole, carebeing taken not to pull the shoe off the shoulder upon which it islanded. To neglect this precaution is to place the pipe in danger ofbeing injured by tools coming in contact with the different sectionsof the pipe that are slightly bowed from the weight of the pipe above. COLLAR-BOUND PIPE. Pipe sometimes becomes collar bound in a hole. In such anevent the pipe can be worked for about the leng
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