Sucker rod coupling, polished rod coupling, and Sub-coupling
1. Introduction of rod coupling
The sucker rod coupling have the same box thread size in each end are used for connecting sucker rod and/or pony rod, and/or sinker bars with sucker rod threads.
The polished rod coupling have the same box thread size in each end are used for connecting polished rod and/or sinker bars with polished rod threads to the sucker rod string.
The sub-coupling have different sizes of box threads in each end are used for connecting two sizes of sucker rods or a polished rod to a sucker rod string.
2. Manufacturing specification: API 11B
3. Material
3.1. Chemical Composition
The material shall be per manufacturer’s specification and shall have a maximum sulfur content of 0.05%.
3.2. Mechanical Properties
Mechanical properties shall be in accordance with the manufacturer’s specification with a minimum tensile strength of 95,000psi(655MPa). One of the following means shall be used to conform to the tensile requirements:
---determination of the metal material hardness of 56 to 62 HRA inclusive; or
---material test report per 6.3.2.2 for the heat of steel from the original mill if further processing does not change mechanical properties; or
---a tensile test per ASTM A370, OR ISO 6892 with s minimum of two tests performed after final thermal processing
