Wedge threads with a solid lubricant coating

Abstract

A tubular connection includes a pin member having external wedge threads configured to engage a box member having corresponding internal wedge threads, and a solid lubricant coating applied on at least one of the internal and external wedge threads wherein the solid lubricant coating comprises a first uniform layer of a dry corrosion inhibiting coating made of an epoxy resin containing particles of zinc and a second uniform layer of a dry lubricant coating covering the first uniform layer.

1 . A tubular connection comprising:
 a pin member having external wedge threads configured to engage a box member having corresponding internal wedge threads; and   a solid lubricant coating permanently bonded on at least one of the internal and external wedge threads.   
     
     
         2 . The tubular connection of  claim 1 , wherein the solid lubricant coating comprises at least two material layers. 
     
     
         3 . The tubular connection of  claim 2 , wherein at least one of the material layers comprises a dry corrosion inhibiting coating made of an epoxy resin containing particles of zinc. 
     
     
         4 . The tubular connection of  claim 2 , wherein at least one of the material layers comprises a dry lubricant coating. 
     
     
         5 . The tubular connection of  claim 2 , wherein at least one of the material layers has a thickness of between about 15 and 35 μm. 
     
     
         6 . The tubular connection of  claim 2 , wherein at least one of the material layers has a thickness of between about 20 and 30 μm. 
     
     
         7 . The tubular connection of  claim 2 , wherein at least one of the material layers has a thickness of between about 10 and 20 μm. 
     
     
         8 . The tubular connection of  claim 2 , wherein at least one of the material layers is comprised of a mixture of molybdenum disulfide (MoS 2 ) and other solid lubricants in an inorganic binder. 
     
     
         9 . The threaded pipe connection of  claim 1 , wherein a surface treatment is applied on at least one of the internal and external wedge threads prior to application of the solid lubricant coating. 
     
     
         10 . The threaded pipe connection of  claim 9 , wherein the surface treatment is selected from a group of surface treatments consisting of abrasive blasting and phosphate coating. 
     
     
         11 . The threaded pipe connection of  claim 1 , wherein the solid lubricant coating is configured to withstand elevated temperatures between about 200° C. and 350° C. 
     
     
         12 . The tubular connection of  claim 1 , wherein the internal and external wedge threads comprise a generally dovetail-shaped cross-section. 
     
     
         13 . The tubular connection of  claim 1 , wherein the internal and external wedge threads have an average surface roughness of between about 2 and 6 μm. 
     
     
         14 . The tubular connection of  claim 1 , wherein the solid lubricant coating comprises a dry corrosion inhibiting coating containing a dispersion of particles of solid lubricant therein. 
     
     
         15 . A method of manufacturing a connection having wedge threads, the method comprising:
 machining internal wedge threads on a box member and external wedge threads on a pin member, wherein the internal and external wedge threads are configured to correspond; and   permanently bonding a solid lubricant coating on at least one of the internal and external wedge threads.   
     
     
         16 . The method of  claim 15 , wherein the permanently bonding comprises providing at least two material layer coatings on at least one of the internal and external wedge threads. 
     
     
         17 . The method of  claim 15 , further comprising providing an average surface roughness of between about 2 and 6 μm on at least one of the internal and external wedge threads prior to permanently bonding at least one of the material layer coatings. 
     
     
         18 . The method of  claim 17 , further comprising providing the average surface roughness of between about 2 and 6 μm on at least one of the internal and external wedge threads using a surface treatment selected from the group consisting of abrasive blasting and phosphate coating.