REMANUFACTURED SUCKER RODS

When TRC was formed, our Board of Directors challenged our managers to redefine the sucker rod reclamation industry. They told us to find better methods and more reliable ways to inspect each rod; not for the purpose of increasing the reject rate, but to give our inspectors the confidence needed to do a proper inspection job. They wanted the old saying “when in doubt, kick it out” eliminated from our vocabulary.

Once the good sucker rods had been identified, they told us to find a way to decrease the residual stresses which had built up in the rod. The mission was to significantly increase the life of each rod that passed inspection. Before TRC entered the sucker rod reclamation business, the goal of the industry was to extend the useful life of a used sucker rod string by inspecting each rod to determine if it was fit for use. If not, the rod was eliminated from the string and the balance was re-run downhole. Over time, the reject rate climbed. It was not uncommon to see reject rates of 60% to 70%.

Through its proprietary shot peening method and by developing other new, innovative processes, TRC is continually improving the industry. Years of testing have proven that TRC’s processes extend the typical fatigue life of your rods by 50% to 100% by reducing the amount of residual stress in the rods. TRC’s historical, weighted average, recovery rate stands at 61%.

TRC’s Remanufacturing Process

While TRC was founded to inspect sucker rods, our continual innovations over the years, have led to our ability to remanufacture sucker rods.

remanufacture

[ree-man-yuhfak-cher]

Rebuilding, repairing, or restoring an equipment or instrument to meet or exceed Original Equipment Manufacturer’s (OEM) performance specifications.  Sold and serviced usually by third-parties, remanufactured items carry a warranty different from the one provided by the OEM.

Anyone can purchase and use shot peening equipment.  However, the “Recipe” is critical to achieving predictable and consistent beneficial results.  Through today, TRC’s Recipe has continually evolved since 1974 when our founder invented the sucker rod inspection process.  In 2016, we achieved a new milestone, whereby our processes demonstrated in tests the repeated ability to increase a used sucker rod’s fatigue life to a level exceeding the fatigue life of newly manufactured sucker rods.  The test results showed that, on average, a used sucker rod processed by TRC had a 50% increased fatigue life versus a new sucker rod that was shot peened by the original manufacturer.

TRC’s processes restore your sucker rods to a level that exceeds the Original Equipment Manufacturer’s performance specifications.  And, they carry a 25-month warranty, exceeding the OEM’s original warranty.

Today, we are remanufacturing sucker rods in two of our Midland plants and are currently retrofitting our other plants to enable them to be able to remanufacture sucker rods in the near future.

SHOT PEENING

Shot peening is the corner stone of TRC’s remanufacturing process.  We understand that many people believe “shot blasting” or “shot cleaning” is the same thing as “shot peening.”  However, there is a technical and material difference between the two processes.  These processes are very different and are applied to achieve different results.

The only similarity between shot blasting and shot peening is that each process involves propelling media at a high velocity to strike a surface.  Shot peening, however, requires control over a consistent size and shape of media, a consistent velocity of media, a consistent volume of media striking the surface area, and for a consistent length of time.  Careful controls yield consistent and repeatable results that are not measurable visually.  Shot blasting is ordinarily less controlled, therefore less expensive, and results can usually be assessed visually.

Shot peening can be measured using several means, both destructively and non-destructively.  The most widely accepted non-destructive, commercially acceptable measurement involves the use of the Almen method, which is the method used at TRC.  All treatments are carefully controlled and documented like a recipe for reliable, consistent, and repeatable results.

TRC shot peens the rods as compared to all other rod service companies that only shot clean their rods.  This process is the cornerstone difference between TRC and our counterparts.  They reclaim your used sucker rods while we remanufacture your used sucker rods.  Our remanufacturing process will reduce the residual stress build up in your rod and will therefore extend the life of your rod by 50% to 100%.

The Shot Peening Process

Shot peening of sucker rods is a cold working process in which the surface is bombarded with small spherical media called shot.  As each individual shot particle strikes the rod surface, it produces a slight rounded depression.  Plastic flow and radial stretching of the surface metal occur at the instant of contact with the edges of the depression rising slightly above the original surface.  The residual stress layer usually extends to about .005” to .010” below the surface.  The metal beneath this layer is not deformed, but the fibers try to restore the surface to its original shape, and the reaction-induced tensile stress develops to achieve equilibrium.  The magnitude of the compressive stress varies, but it will normally have a value of at least one-half the yield strength.

Benefits of Shot Peening

Benefits obtained by shot peening are the result of the effect of the compressive stress and the cold working induced.  Compressive stresses are beneficial in increasing resistance to fatigue failures, corrosion fatigue, stress corrosion cracking, and hydrogen assisted cracking (Hydrogen Embrittlement).

Fatigue Failures

Shot peening is effective in reducing sucker rod fatigue failures caused by cyclic loading.  These failures usually originate in surface areas under tension load, and cracks propagate from a surface defect or other stress risers.  Shot peening prevents suck failures by inducing an even, compressive stress layer in the surface of the sucker rod, permitting an increase in service life or the allowable stress level.  As a shot peened sucker rod is loaded, its critical surface area will not develop tensile stresses until the peen induced compressive stresses are first overcome.  The American Petroleum Institute states, “We consider shot peening, when properly controlled and applies, a satisfactory method of cold working a metal surface to improve fatigue life.”

Stress Corrosion Cracking

Stress corrosion cracking is defined as failure by cracking under combined action of corrosion and static tensile stress, either external (applied) or internal (residual).  It is a complex interaction of sustained tensile stress at a surface and corrosive attack that can result in brittle failure.  Stress corrosion cracking cannot occur in an area of compressive stress.  The compressive stresses induced by shot peening can effectively overcome the surface tensile stresses that cause stress corrosion.

Hydrogen Embrittlement

Atomic hydrogen is extremely mobile and able to easily penetrate and interact with metal, greatly reducing ductility and its ability to withstand cyclic loads.  Shot peening has been shown to be effective in retarding the migration of hydrogen through metal.

Surface Integrity

Shot peening improves the surface integrity of the sucker rod, because no matter how carefully it is manufactured, it still contains minute surface imperfections. These may be localized areas of tensile stress, or pits, scratches, and other surface imperfections.  As peening cold-works the rod surface, it blends small surface imperfections and effectively eliminates them as stress concentration points. 

CONTACT US

For general inquiries to TRC, please fill out the form below for a quick response. If you'd like to contact TRC via telephone or e-mail, please visit our Contact Page for our office nearest you.

TRC Services, INC.

Let us be your partner against the war on sucker rod failures. Since 1996, we have been obsessed with transforming the industry.