Arrow-shaped thread form for tubular connections
A thread form is shown which is used to make a threaded pipe connection capable of being screwed together and subsequently unscrewed. A pin member has external threads with stab flanks and load flanks and flat crests and roots for mating with the mating internal threads of a box member to make up a pipe connection. The stab flanks and load flanks form a distinct geometric profile which is arrow-shaped when viewed in profile. The arrow profile can be cut in either of two opposite directions. Each profile includes only two facets with the facets on the stab flank and the facets on the load flank both leaning in the same direction with respect to the longitudinal axis of the pipe, when viewed in profile.
1. A thread form for making a threaded pipe connection capable of being screwed together and subsequently unscrewed, the thread form comprising:
a pin having external threads with stab flanks and load flanks and flat crests and roots for mating with the mating internal threads of a box to make up a pipe connection, and wherein the stab flanks and load flanks are each comprised of only two facets, and wherein the facets on the stab flanks and the corresponding facets on the load flanks of each thread both lean in the same direction in imaginary parallel planes, so that the facets form an arrow-shape when viewed in profile; and
wherein the presence of only two facets on each of the respective stab flanks and load flanks and the fact that the respective corresponding facets on the stab and load flanks both lean in the same direction allow the thread form to be machined in either of two opposite directions resulting in thread forms which are exact mirror images of one another, one mirror image thread form being useful for pipe connections where the pipes are in tension and one mirror image thread form being useful for pipe connections where the pipes are in compression.
2. The thread form of claim 1 , wherein the threads are formed with a negatively sloped facet which forms a hook at the base of the load flank.
3. The thread form of claim 1 , wherein the threads have a given thread height defined between the thread crests and thread roots, wherein the thread crests and the thread roots have a given width, and wherein the width at or near the thread crests is less than the width measured at the thread roots.
4. The thread form of claim 1 , wherein the threads are tapered threads having a given angle of taper with respect to a longitudinal axis of the pipe.
5. The thread form of claim 1 , wherein the thread roots and crests are parallel to the longitudinal axis of the pipe.
6. The thread form of claim 1 , wherein the threads are helically structured as a wedge.
7. The thread form of claim 1 , wherein the connection is used with a tubular selected from the group consisting of oil, gas, construction, water and waste disposal well casing and tubing.
8. A make and break threaded pipe connection capable of being screwed together and subsequently unscrewed, the threaded pipe connection comprising:
a box having internal threads with stab flanks and load flanks and flat roots and crests;
a mating pin having external threads with stab flanks and load flanks and flat crest and roots for mating with the mating internal threads of the box to make up a pipe connection, and wherein the pin stab flanks and load flanks are each comprised of only two facets, and wherein the facets on the stab flanks and the corresponding facets on the load flanks of each thread on the pin both lean in the same direction in imaginary parallel planes, so that the facets form an arrow-shape when viewed in profile which mates with a corresponding thread profile on the box
wherein the presence of only two facets on each of the respective stab flanks and load flanks and the fact that the respective corresponding facets on the stab and load flanks both lean in the same direction allow the thread form to be machined in either of two opposite directions resulting in thread forms which are exact mirror images of one another, one mirror image thread form being useful for pipe connections where the pipes are in tension and one mirror image thread form being useful for pipe connections where the pipes are in compression.
9. The make and break threaded connection of claim 8 , wherein the connection is used with a tubular selected from the group consisting of casing and tubing for oil, gas, water and waste disposal wells.