Sinker bar

Sanjack owns a strong ability about research, design and production of sinker bar with decades of manufacturing experience. Sanjack has been certified by ISO9001,  ISO14001 and OHSAS18001.Sanjack adopts the principle of combining intl standards, national standards and users’ views for design.

Sinker bars of Sanjack are exported to the United States, Canada, Europe, Africa and Middle East, and we establish cooperative relationships with international customers all over the world.

Sinker Bar is heavier than the conventional rod. It is used at the bottom of the sucker rod string to keep the rod string under tension and reduce crooks of the sucker rod string during downward travel.Sinker bars provide concentrated weight above the pump to help keep the rod string straight and in tension, which reduces buckling of the sucker rods or the pump plunger. Sinker bars are made of hot rolled carbon manganese steel bar. Sinker bars are surface turned and have  double sucker rod pins, shoulders, and wrench flats on both ends. One end has a reduced section for elevator seating and lifting.

Grade and material

The current edition of intl standards recognizes two grades of sinker bars,Grade 1 Carbon steel and Grade 2 Alloy steel.

Below are the material examples

  1. AISI 1024 Plain Carbon Steel 65,000 psi minimum tensile
  2. AISI 4623 Nickel-Molybdenum Alloy Steel 90,000 psi minimum tensile.

Sinker bar also have C,D,K strength grades as sucker rods.

In general terms  Grade 1 is referred to as Grade C while Grade 2 is referred to as Grade K depending on material alloy type.

The following is the data sheet of common sizes and mechanical properties of sinker bar.


External diameter (mm) External thread
dimensions (mm)
Wrench square
width (mm)
Wrench square
length (mm)
Sinker bar
length  (mm)
1 1/4(31.75) 5/8(15.9)SR 25.4 31.8 7600;9100 1. Class-1:
tensile strength≥448MPa
1 1/4(31.75) 3/4(19.1)PR 25.4 31.8 7600;9100
1 3/8(34.93) 5/8(15.9)SR 25.4 31.8 7600;9100
1 3/8(34.93) 3/4(19.1)PR 25.4 31.8 7600;9100
1 1/2(38.1) 3/4(19.1)SR 33.3 38.1 7600;9100 2. Class-2:
tensile strength≥620MPa
1 5/8(41.28) 7/8(22.2)SR 33.3 38.1 7600;9100
1 3/4(44.45) 7/8(22.2)SR 38.1 41.3 7600;9100


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