Overview
ISO 10431:1993 - "Petroleum and natural gas industries - Pumping units - Specification" adopts API Specification 11E (16th edition, 1989) (with Supplement 1, 1991) as an international standard for the design and rating of beam-type pumping units used in the petroleum and natural‑gas industries. The standard defines requirements for dimensional characteristics, mechanical properties, gauging practice and rating methods, and specifies conversion of English units to SI in accordance with ISO 31. ISO 10431 includes modifications for international application and notes that Appendix G (API monogram use) is informational only.
Key topics and requirements
- Scope and applicability
- Covers design and rating of pumping‑unit structures, gear and chain reducers, beam and crank counterbalances.
- Does not cover chemical properties of materials or the operational use of equipment; engineering judgment remains necessary.
- Design and rating methods
- Standardizes rating procedures for polished‑rod capacity and gives allowable working stresses for structural members (walking beams, saddles, etc.).
- Provides a walking‑beam rating formula and defines critical dimensions (A, C, lf) and section limitations (no holes/welds in tension flange critical zone).
- Dimensional and conversion practice
- Requires unit conversions per ISO 31 (Parts 1 and 3). Examples included in the text:
- 1 in = 25.4 mm (exact)
- 1 ft = 0.3048 m (exact)
- 1 lb = 0.45359237 kg (exact)
- 1 psi = 6894.76 Pa
- 1 in^3 = 16.387064 × 10^-3 dm^3
- Appendices and supplementary guidance
- Approved data forms (Appendix A).
- Recommended practices for calculation/application of torque factors for various lever geometries and counterbalances (Appendices B–F).
- Appendix F: torque ratings for gear reducers.
- Appendix G: API monogram guidance (informational only).
Applications and users
ISO 10431 is intended for:
- Manufacturers of beam‑type pumping units and component suppliers (reducers, counterbalances, beams).
- Design and mechanical engineers working on rod‑pump surface equipment who need standardized rating and dimensional guidance.
- Procurement and quality inspectors specifying product acceptance criteria and gauging practice.
- Oilfield service companies evaluating retrofit, repair or replacement of surface pumping equipment.
Use cases:
- Specifying compliant pumping‑unit structures for well lifting capacity.
- Determining allowable stresses and ratings for walking beams and reducers.
- Calculating torque factors and selecting appropriate gear or chain reducers.
Related standards
- API Specification 11E (Spec 11E), 16th edition - adopted by ISO 10431.
- ISO 31 (Parts 1 & 3) - unit conversion rules referenced for SI conversions.
- ISO/TC 67 - technical committee responsible for petroleum and natural gas equipment standardization.
Keywords: ISO 10431, pumping units, API Spec 11E, pumping‑unit specification, walking beam, gear reducer, torque factor, oilfield pumping equipment, unit conversion.
