Quality control for sucker rods

• US 4,700,577 A
• Filed: 10/09/1986
• Issued: 10/20/1987
• Est. Priority Date: 06/11/1984
• Status: Expired due to Fees

• Current Assignee: Shell Oil Company (Shell Plc)
• Original Assignee: Shell Oil Company (Shell Plc)
• Inventors: Tripp, Harley A.
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US06/917,282
• Time in Patent Office: 376 Days
• Field of Search: 73/587, 73/789, 73/791, 73/801, 73/826, 73/827, 73/795, 73/796
• US Class Current: 73/801
• CPC Class Codes: G01N 29/14 using acoustic emission techniques echo of particles G01N29/046; measuring mechanical vibrations or acoustic waves in solids in general G01H1/00
• CPC Class Codes: G01N 3/08 by applying steady tensile or compressive forces G01N3/28 takes precedence
• CPC Class Codes: G01N 33/386 Glass

Abstract

A method for testing fiberglass sucker rods wherein the rod is pulled to a predetermined stress level while measuring the load, elongation and acoustic emissions. The load versus displacement is plotted in real time while the measured values are used to calculate the modulus of elasticity for various load ranges. From the measurements and calculated modulus of elasticity the quality of the rod can be determined.

Claims

1. A method for testing the overall quality of a fiberglass sucker rod having a known ultimate strength, comprising:

applying tension loads that are less than said known ultimate strength to the end fittings of such a rod,

measuring the applied loads and elongation for such a rod,

measuring the acoustic emissions from such a rod during said applying of said tension loads,

determining from said measured loads and elongation the modulus of elasticity for at least two different load ranges, and

determining from the difference between said moduli of elasticity whether said end fittings of such a rod are acceptably attached and from said measured acoustic emissions whether the material of such a rod is acceptable.

2. The method of claim 1, wherein said difference between said moduli of elasticity is less than five percent for an acceptable rod.

3. The method of claim 2, further comprising:

comparing said measured acoustical emissions with a statistically determined number to determine if such a rod is acceptable.