Sinker Bars
Sinker bars are used between sucker rods and oil pumps. With its weight, the sinker bar keeps the sucker rods at tension and at the center of the oil pipe, so as to prevent the sucker rod from bending in the oil well and causing friction with the internal wall. The sinker bars comply with API Spec 11B Standards.
Sinker bars are made of high-quality hot-rolled carbon steel or Cr-Mo structural alloy steel. There are external threads, which are the same as that of sucker rods or polished rods, shoulders and wrench flats at both ends and a elevator neck at one end. There are six specifications: 1-1/8", 1-1/4", 1-3/8", 1-1/2", 1-5/8" and 1-3/4". In application, the sinker bar can connect with the upper polished rod as well as the sucker rod below in the oil well.
Material Specification and Mechanical Property| Grade | Material | Chemical Composition (wt.%) | MPa | ||||||||
| C | Mn | Si | Cr | Mo | Ni | V | S | P | |||
| 1 (C) | 45 (AISI 1045) | 0.42～0.50 | 0.50～0.80 | 0.17~0.37 | ≤ 0.25 | -- | ≤ 0.25 | -- | ≤ 0.035 | ≤ 0.035 | 621 |
| 2 (K) | 20Ni2MoA (AISI 4620) | 0.18~ 0.23 | 0.70~ 0.90 | 0.17~ 0.37 | ≤0.35 | 0.20~ 0.30 | 1.65~ 2.00 | 0.04~ 0.08 | ≤ 0.025 | ≤ 0.025 | 621 |
| 3 (D) | 42CrMoA (AISI 4142) | 0.38~ 0.45 | 0.50~ 0.80 | 0.17~ 0.37 | 0.90~ 1.20 | 0.15~ 0.25 | ≤0.30 | ≤ 0.07 | ≤ 0.025 | ≤ 0.025 | 793 |
