Polished Rod, it is designed and manufactured in accordance with the latest edition of the API specification 11B. Our polished rods and couplings are furnished with cold formed fully rolled threads. And they are made from fine quality alloy steel, featured by high strength, smooth surface and long service life. The tensile strength of polished rods are a range of 655 to 1102 Mpa. Regular polished rods are connected to polished rods coupling, and end upsetting polished rods are connected to sucker rod coupling in use. This technique ensures a perfect thread on each and every pin. The burnished thread surface that results from rolled threads improves resistance to corrosion and reduces abrasion within the thread. The work hardened flank provides increased surface tensile, yield and shear strength. Due to pressure deformation, a residual compressive stress system builds up at the thread root, which counteracts tensile loading.