Monthly Archives: November 2019

Steel Sucker Rod and Pony Rod Differences

What is API 11B Steel Sucker Rod?

Steel sucker rod is a kind of long slender bar used in pumping well, common benchmark is API SPEC 11B (Specification for sucker rods, polished rods and liners, couplings, sinker bars, polished rod clamps, padding boxes, and pumping tees). It connects with polished bar above, and pumps at the underside. The function is to transmit the power.

Steel sucker rods length in general at 7.6 or 8 meters long, material usually use high-carbon steel and surface plating with hard chrome, in the tubing connected one by one until the piston at the oil layer to pump oil with up-and-down progress.

Steel sucker rod scope

The standard API 11B for sucker rod define the specifications for a size, mechanical property, inspection and test methods. Covers products general sucker rod, fiber-strengthen plastic sucker rod, reducing coupling, polished coupling, and polished bar.

Steel Sucker Rod Classification

  • Ordinary sucker rod cover: Grade C, D, K, KD sucker rod.
  • High-strength sucker rods covers: Grade H sucker rod, include 3 types: HY, HL, KHL.
  • Unique sucker rods: Hollow sucker rod, steel rod.
  • Consecutive sucker rods: Steel rod.
  • Screw pump used unique sucker Rod: Taper thread sucker rod, plugging-type sucker rod.
  • Fiberglass reinforced plastic sucker rod: Fiber plastic sucker rod.
  • Flexible sucker rod: Carbon fiber well-matched material sucker rod, wire rope sucker rod.
  • Other sucker rod: Electric sucker rod.

Grades and types

Grade C: Covers steel rod used in light-to-medium load and noncorrosive or anti-corrosive oil well. Manufactured an AISI 1530 Mod steel.

Grade K: Covers steel rod used in corrosive light-to-medium load oil well. Manufactured in AISI 4621 Mod steel.

Carbon steel Grade D: Steel rod used in noncorrosive or anti corrosive medium-to-heavy load oil well. And Manufactured a AISI 1530 Mod low-alloy steel.

Alloy steel Grade D: Covers steel rod used in noncorrosive & anti corrosive medium-to-heavy load oil well. Manufactured an AISI 4142 Mod.

Grade KD sucker rod: Covers sucker rod which a both have anti-corrosion properties of grade K, & mechanical properties of grade D. Manufactured in AISI 4320 Mod steel.

Grade D special sucker rod: Covers steel rod which used in medium-to-heavy anti corrosive oil well. Manufactured a 4330 Mod steel.

Grade H sucker rod: Covers steel rod which used in heavy-to-overweight load oil well.

Type HL sucker rod: Covers steel rod which by selecting appropriate material & process achieve grade H.

Type HY sucker rod: Covers steel rod which through quenching process to make the mechanical properties achieve grade H.

What is a Pony Rod?

Pony rod is a kind of sucker rod, shorter than usual length of a sucker rod. Pony rod used to make up a sucker rod string of required length, which connects a piston pump to surface of oil well. The rod connect with thread from both ends, diameters are in general at 3/4 inch, 7/8 inch and 1 inch. Due to great tensile, pony rod apply in various circumstances. Such as high loads, corrosive environment so it can control over the rod friction well again. As it manufactured in AISI 1530 Mod, pony rod has perfect performance even in deep oil well.

The pony rod is a key part of the artificial lift system, for this reason it should be done by different heat treatments to maximize performance to anti weariness. Commonly pony rod have three main grades: Grade C, K & D and these grades are classified by different tensile strength. For instance, grade C has a maximum tensile strength of up 115,000 psi whereas grade K has maximum tensile strength of up to 140,000 psi. The pony rod is placed beneath the polished rod of the rod string to prevent the string from falling down. In addition, the old rods should not be used for load carrying part to avoid any mistake

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