Sucker rod coupling with protective coating

An oil well having:

• a. a string of individual oil well sucker rods, extending within said well,
• b. said string of sucker rods connected to a pump-jack at the surface of the earth to a pump within a reservoir of oil beneath the surface of the earth,
• c. couplings connecting the individual rods together to form a string,
• d. each coupling being a cylindrical metallic cuff having a radial face at each end and internal threads for its entire length;
• wherein the improved structure comprises:
• e. a resinous coating fusion bonded over all external surfaces, including
• f. said radial faces at each end of the cuff, and
• g. said resinous coating is chosen from the group consisting of Nylon, Teflon, and Ryton.

In an oil well having:

• a. a string of individual oil well sucker rods,
• i. extending within said well,
• ii. having a threaded pin on each end, and
• iii. having a shoulder adjacent to each pin,
• b. said string of sucker rods connected to a pump-jack at the surface of the earth to a pump within a reservoir of oil beneath the surface of the earth,
• c. couplings connecting the individual rods together to form said string,
• d. each coupling being a cylindrical metallic cuff having a radial face at each end and internal threads for its entire length, said pins threaded into said cuffs;
• the improved structure comprising:
• e. a resinous coating about 0.040 thick fusion bonded over all exposed surfaces,
• f. said resinous coating is chosen from the group consisting of Nylon, Teflon, and Ryton, and
• g. said radial faces making metal-to-metal contact with shoulders upon said sucker rods.

A coupling adapted to be used in a string of oil well sucker rods, said improved coupling comprising:

• a. a cylindrical metallic cuff having a radial face at each end and internal threads for its entire length, having
• b. a resinous coating bonded over all of the external surfaces,
• c. said resinous coating is fused onto the metal,
• d. a distal plug within one end of said cuff,
• e. said distal plug snugly fitting the threads of one end and covering all internal surfaces, and
• f. an eyelet plug on the other end,
• g. said eyelet plug extending within the other end and covering the threads of that end and all internal surfaces.