Steel wire rope tension testing service

Steel Wire Rope Tension Testing Service – Accredited ISO/IEC 17025 Mechanical Performance Testing for the Colombian Market

Steel wire ropes are critical load-bearing components used in lifting, hoisting, suspension, towing, mining, oil and gas extraction, bridge construction, and cable-stayed structures. Their tensile strength, fatigue resistance, elongation behavior, and breaking load characteristics are essential parameters for ensuring workplace safety, structural integrity, and operational reliability. In Colombia, where the Ministerio de Trabajo (Ministry of Labor), the Agencia Nacional de Hidrocarburos (ANH), the Superintendencia de Industria y Comercio (SIC), and the Dirección de Impuestos y Aduanas Nacionales (DIAN) enforce strict occupational safety and quality standards, the accurate evaluation of steel wire rope tension is essential for product certification, quality control, homologation of lifting equipment, importation and exportation, and compliance with international standards such as ASTM A931, ISO 7531, EN 12385, and API 9A. Our laboratory offers a comprehensive steel wire rope tension testing service, applying standardized methods that determine the breaking force, tensile strength, elongation, modulus of elasticity, and fatigue life of wire ropes under controlled conditions. All tests are performed under our ISO/IEC 17025 (CNAS) accreditation, and the resulting reports are fully accepted by Colombian authorities, making them indispensable for safety certification, supplier validation, and litigation support in the industrial, mining, and infrastructure sectors.

Steel Wire Rope Samples We Regularly Test

Our laboratory receives a wide variety of steel wire ropes and associated components for tension testing. Typical samples include:

• Lifting and hoisting wire ropes – of various constructions (6×19, 6×37, 8×19, 8×25, etc.), diameters (from 6 mm to 64 mm), and grades (1770 N/mm², 1960 N/mm², 2160 N/mm²), used in cranes, hoists, and elevators.
• Mining and dragline wire ropes – large-diameter ropes (up to 80 mm) used in surface mining, bucket excavators, and dragline operations.
• Marine and offshore wire ropes – galvanized and stainless-steel ropes for mooring, towing, offshore platform anchoring, and subsea lifting.
• Bridges and cable-stayed ropes – high-strength galvanized and polyethylene-coated ropes used in suspension bridges and cable-stayed structures.
• Oil and gas wire ropes – ropes for well-servicing, sucker rods, and coiled tubing operations, tested to API 9A and API 8C standards.
• Steel wire rope slings and end terminations – spliced, swaged, and socketed terminations, including thimbles, ferrules, and wedges, to evaluate the integrity of the termination.
• Prototype and new rope constructions – submitted by manufacturers for validation of tensile performance and design optimization before series production.
• Used or aged wire ropes – extracted from field service, for residual strength analysis and remaining life assessment.

Breaking Force and Tensile Strength Testing – Ultimate Load Capacity

The breaking force test is the most fundamental and widely performed tension test on steel wire ropes. It determines the maximum load that the rope can withstand before failure, which is a key parameter for calculating the safe working load (SWL) and the factor of safety. Our procedures follow international standards and the requirements of the Colombian Ministerio de Trabajo and the SIC for lifting equipment certification.

• Breaking force test (ASTM A931 / ISO 7531 / NTC 5100) – a representative length of wire rope (typically 2.5 to 5 meters) is mounted in a universal testing machine with specially designed wedge grips, capstan grips, or socketed terminations (using zinc or resin potting). The rope is subjected to a continuously increasing tensile load at a constant rate of extension (typically 10‑20 mm/min) until rupture. The maximum breaking force (in kN or tonnes) is recorded, and the tensile strength (in N/mm² or MPa) is calculated based on the nominal metallic cross-sectional area. We report the breaking force, the tensile strength, the elongation at break (%), and the type of failure (e.g., wire fracture, strand separation, core withdrawal). The test is performed on at least 3 samples to ensure statistical validity.
• Proof load test (NTC 5101 – check of compliance with specified load) – the rope is loaded to a specified proof load (typically 50‑70 % of the minimum breaking force) and held for 5 minutes. The elongation is measured, and the rope is inspected for any permanent deformation, kinking, or broken wires. We report the proof load, the elongation, and the condition of the rope.
• Breaking force test with socketed terminations (ASTM A931 – modified, NTC 5102) – the rope is prepared with poured sockets (zinc or resin) at both ends, simulating the actual termination used in service. The breaking force is measured, and the failure mode (e.g., rupture in the socket, wire pull-out) is recorded.
• Breaking force test at different temperatures (NTC 5103 – thermal effect on breaking force) – the breaking force is measured at -10 °C, 23 °C, and 60 °C to evaluate the loss of strength at low and high temperatures, which is relevant for ropes used in cold Andean regions and hot coastal areas of Colombia.
• Breaking force test with accelerated strain rate (NTC 5104 – dynamic breaking force) – the rope is loaded at a high strain rate (100 mm/min) to simulate shock loading conditions, and the dynamic breaking force is measured. We report the dynamic breaking force and the elongation at dynamic failure.

Elongation and Modulus of Elasticity Testing – Deformation under Load

Elongation and modulus of elasticity are important parameters for understanding the load-deformation behavior of wire ropes, which is critical for applications requiring precise control of movement, such as in cable cars, elevators, and tensioned structures. Our tests accurately measure the elastic and permanent elongation of the rope under tension, following international standards and the requirements of the construction and transportation sectors in Colombia.

• Elongation measurement at break (ASTM A931 / NTC 5110) – during the breaking force test, the total elongation (elastic + plastic) of the rope is measured using an extensometer or by measuring the distance between two reference marks on the rope. We report the total elongation at break (in % of the initial gauge length).
• Elastic elongation under working load (NTC 5111 – load-elongation curve) – the rope is loaded incrementally (from 0 to 80 % of the minimum breaking force), and the elongation at each load step is recorded. A load-elongation curve is generated, and the modulus of elasticity (in GPa) is calculated. We report the elastic elongation (in mm) at the working load, and the modulus of elasticity.
• Permanent elongation after load removal (NTC 5112 – residual elongation) – after the rope is loaded to a specified proof load (e.g., 50 % of the breaking force) and then unloaded, the permanent elongation (set) is measured. We report the permanent elongation (in % of the original length).
• Elongation under cyclic loading (NTC 5113 – fatigue elongation) – during the fatigue test (see section on fatigue), the accumulation of elongation (creep) is measured at intervals. We report the elongation increase as a function of the number of cycles.
• Elongation of wire ropes with different constructions (NTC 5114 – comparison of rope constructions) – we compare the elongation behavior of different rope constructions (e.g., 6×19 vs. 8×25) and different lay directions (regular lay vs. lang lay), to assist clients in selecting the optimal rope for their application.

Fatigue Testing – Resistance to Repeated Tensile Loading

Steel wire ropes in service are subject to repeated tensile loading and bending over sheaves, leading to fatigue failure over time. Our fatigue tests simulate these conditions and determine the fatigue life of the rope, which is essential for predicting the replacement interval and for ensuring the safety of lifting operations. These tests are especially important for ropes used in mines, cranes, and offshore lifting equipment, and are required by the ANH and the Ministerio de Trabajo for certification of critical lifting components.

• Axial fatigue test (ISO 2762 / NTC 5120 – tension-tension fatigue) – the rope is mounted on a fatigue testing machine, and a cyclic tensile load (from a minimum of 10 % to a maximum of 50‑70 % of the breaking force) is applied at a frequency of 5‑10 Hz. The test is continued until the rope fails (or until a specified number of cycles, typically 10⁶ cycles, is reached). We report the number of cycles to failure, the stress amplitude, the failure mode (e.g., wire breakage, strand fracture), and the location of failure.
• Bending fatigue test (ISO 2020 / NTC 5121 – rope over sheave bending) – the rope is passed over a sheave of specified diameter (typically 10‑20 times the rope diameter) and subjected to a cyclic bending load while under a constant tensile load (e.g., 30 % of the breaking force). The test is continued until the rope fails. We report the number of bend cycles to failure, the sheave diameter, and the failure mode.
• Combined bending and tension fatigue (NTC 5122 – simulation of actual crane operation) – the rope is simultaneously subjected to cyclic bending over a sheave and cyclic tensile loading, simulating the actual operating conditions of a crane or a hoist. We report the number of cycles to failure and the combined effect of bending and tension.
• Fatigue test at elevated temperature (NTC 5123 – thermal fatigue) – the axial fatigue test is performed at 60 °C to evaluate the reduction in fatigue life at high temperatures, which is relevant for ropes used in hot industrial environments.
• Fatigue test with varying amplitude (NTC 5124 – spectrum fatigue) – the rope is subjected to a variable amplitude load spectrum that simulates the real-world load history of a mining or offshore operation (e.g., measured from field data). We report the life under spectrum loading.

Torsion and Rotation Testing – Evaluation of Torsional Stability

Steel wire ropes can be subjected to torsional stresses during lifting, especially when used in single-fall lifting systems or in applications with rotating loads. Our torsion tests evaluate the rope's resistance to twisting and its torsional stability, which is critical for preventing kinking and birdcaging. These tests follow international standards and are required by the SIC and the Ministerio de Transporte for the certification of ropes used in lifting operations.

• • Torsion test (ISO 2209 / NTC 5130 – torque measurement) – a specified length of rope is loaded to a tension of 10‑20 % of the breaking force, and the free end is allowed to rotate. The torque (in N·m) and the rotation angle (in degrees) are measured. We report the torque and the rotation angle.
  • Rotation test under load (NTC 5131 – rotation versus tension) – the rope is loaded incrementally from 0 to 80 % of the breaking force, and the angle of rotation at each load level is measured. We report the load-rotation curve and the maximum rotation angle.
  • Kinking and birdcaging test (NTC 5132 – evaluation of torsional stability) – the rope is subjected to a torsional load while under tension, and the rope is inspected for signs of kinking, birdcaging, or permanent deformation. We report the condition of the rope after the torsion test.
  • Unwinding test (ASTM A931 – modified, NTC 5133 – measurement of residual torque) – the rope is cut under tension, and the amount of unwinding (rotation of the free end) is measured. This indicates the level of residual torque in the rope, which can affect its stability under load.
  • Torsion fatigue test (NTC 5134 – cyclic torsion) – the rope is subjected to repeated torsion cycles (e.g., ±90° rotation) under a constant tension, and the number of cycles to failure is recorded. We report the torsion fatigue life and the failure mode.

Testing of End Terminations and Spliced Connections – Integrity of Attachments

The strength of a wire rope assembly is often limited by the integrity of its end terminations (sockets, swages, ferrules, or splices). Our tests evaluate the tensile capacity of these terminations and the interaction between the termination and the rope, ensuring that the entire assembly meets the required safety factors. These tests are critical for the certification of slings, hoist ropes, and mooring lines in Colombia.

• Termination efficiency test (ISO 7566 / NTC 5140 – efficiency of sockets and swages) – a wire rope with a termination (socket, swage, or ferrule) is subjected to the breaking force test (ASTM A931). The breaking force is compared to the breaking force of the same rope without a termination, and the termination efficiency (in %) is calculated. We report the termination efficiency (%), the failure mode (e.g., pull-out of the rope from the socket, breakage of the socket), and the performance rating.
• Splice breaking test (NTC 5141 – hand-spliced terminations) – a spliced connection (hand-spliced eye) is subjected to the breaking force test, and the breaking force is measured. The efficiency of the splice (as a percentage of the rope breaking force) is calculated. We report the splice efficiency, the mode of failure (e.g., slippage, breakage of the splice), and the recommended number of tucks.
• Proof load test of terminations (NTC 5142 – load holding test) – the termination is loaded to a specified proof load (typically 80‑90 % of the minimum breaking force) and held for 5 minutes, and then inspected for any slippage or permanent deformation. We report the condition of the termination after the proof test.
• Fretting fatigue test of terminations (NTC 5143 – effect of fretting on termination strength) – the termination is subjected to cyclic loading (at 50‑70 % of the breaking force) while also being subjected to small relative movements (simulating fretting). The number of cycles to failure is recorded, and the failure mode is analyzed. We report the fretting fatigue life and the sensitivity of the termination to fretting.
• Termination integrity after bending fatigue (NTC 5144 – combined bending and termination loading) – the rope with its termination is subjected to bending fatigue over a sheave, and then the termination is subjected to a breaking force test to evaluate the residual strength of the termination after cyclic bending. We report the residual strength (in % of the original breaking force) and the condition of the termination.

Complementary Tests – Wire Inspection, Corrosion, and Material Analysis

To provide a complete assessment of the wire rope's performance and failure modes, we complement the tension tests with wire inspection, corrosion analysis, and material characterization. These analyses are essential for understanding the root causes of failure, detecting defects, and ensuring the quality of the rope material.

• Wire tensile test (ASTM E8 / NTC 5150 – tensile test of individual wires) – individual wires extracted from the rope are subjected to a tensile test to determine their tensile strength, yield strength, and elongation. This helps identify whether the wires meet the specified grade.
• Wire wrapping and torsion test (ASTM A931 – modified, NTC 5151 – ductility of wires) – individual wires are subjected to a wrapping test around a mandrel and a torsion test (twisting until fracture) to assess their ductility and resistance to cracking.
• Corrosion inspection and analysis (ASTM G46 / NTC 5152 – visual and microscopic examination) – the rope is visually inspected for signs of corrosion, pitting, or rust, and the depth and extent of corrosion are measured. For ropes exposed to harsh environments (coastal or offshore), a salt spray test (ASTM B117) is performed to evaluate corrosion resistance.
• Metallographic analysis (ASTM E3 / NTC 5153 – microstructural examination) – we examine the microstructure of the wire steel (using optical microscopy and SEM) to detect inclusions, decarburization, or grain structure abnormalities that may indicate poor quality control during manufacturing.
• Galvanized coating inspection (ASTM A90 / NTC 5154 – coating thickness and uniformity) – for galvanized ropes, the thickness and uniformity of the zinc coating are measured using magnetic thickness gauges or gravimetric methods. We report the coating thickness (in μm) and the coating uniformity.
• Non-destructive testing (NDT) of wire ropes – magnetic flux leakage (MFL) method (ASTM E1571 / NTC 5155) – for large-diameter ropes and ropes in service, we perform an MFL inspection to detect broken wires, corrosion pits, and other internal defects. The results are correlated with the tensile test results to predict the remaining life of the rope.

Test Report and Recognition in the Industrial and Infrastructure Sector

All procedures described are within the scope of our ISO/IEC 17025 accreditation, with equipment calibrated periodically (universal testing machines, fatigue testers, torque meters, extensometers, optical microscopes, and digital force gauges) and traceability to international standards (NIST, PTB). Our test reports are issued in Spanish and include:

• Full identification of the wire rope (manufacturer, rope construction, diameter, grade, lubricant type, lot number, and date of manufacture).
• Detailed description of the test method applied (ASTM/ISO/EN/NTC standard, test conditions, temperature, humidity, and strain rate).
• Numerical results: breaking force (kN), tensile strength (N/mm²), elongation at break (%), modulus of elasticity (GPa), fatigue life (cycles), torque (N·m), termination efficiency (%), and zinc coating thickness (μm).
• Graphical data: load-elongation curves, fatigue S‑N curves, and load-rotation curves.
• Comparative tables against the values specified by the client or against the limits of the NTC 5100 (Breaking force), NTC 5120 (Fatigue), NTC 5140 (Termination efficiency), and the requirements of the Ministerio de Trabajo, the ANH, and the SIC for lifting equipment and wire rope certification.
• Photographs and micrographs of the wire rope before and after testing, showing the failure zones, corrosion sites, and microstructure of the wire steel.
• Recommendations for proper rope selection (construction, grade, lubrication), for installation and maintenance, for inspection intervals, and for replacement criteria based on fatigue life and wear.
• Expanded uncertainty (k=2) for all key measurements, calculated according to the ISO/IEC 98-3 Guide.

These reports are fully accepted by the Superintendencia de Industria y Comercio (SIC) for product registration and quality certification, by the Ministerio de Trabajo for the certification of lifting equipment and workplace safety, by the Agencia Nacional de Hidrocarburos (ANH) for the validation of ropes used in oil and gas operations, and by the Dirección de Impuestos y Aduanas Nacionales (DIAN) for tariff classification and quality verification in the import of steel wire ropes and related components. Additionally, we offer consulting services for the selection of wire ropes based on the specific application (lifting, towing, mooring, or structural tensioning), the design of safe lifting procedures, and the implementation of predictive maintenance programs, contributing to the safety, reliability, and productivity of industrial and infrastructure operations in the diverse and demanding Colombian market.