Proof Load Testing vs. Load Testing Explained | Aldinger

"Load testing" and "proof load testing" are often used as if they mean the same thing. They don't. Mixing them up can leave a crane, hoist, or rigging assembly without the test that OSHA, your insurer, or your customer actually requires.

This guide explains how proof load testing and load testing differ, when each one is required, and what to look for in a provider.

Quick answer: what's the difference between proof load testing and load testing?

Proof load testing applies a controlled load above an item's rated capacity, typically 125% for cranes, to prove it can safely carry its rated load. Load testing is the broader term for any test that applies a known load to verify performance, which can be at, below, or above the rated capacity. Every proof load test is a load test, but not every load test is a proof load test.

What is load testing?

Load testing is any test that applies a known, measured force to equipment or a structure to confirm how it performs. The load can be applied with certified deadweights, water bags, hydraulic rams, or a calibrated load cell, depending on the item and the capacity.

Common types of load testing include:

• Rated load testing: applying 100% of the rated capacity to confirm normal performance, often used for periodic checks.
• Static load testing: holding a load in place to check for deflection, slippage, or deformation.
• Dynamic load testing: moving the load through the equipment's normal motions (hoisting, lowering, traveling) to check brakes, controls, and limit switches.
• Destructive or break testing: loading a sample until it fails to find its actual breaking strength. This is used in product development, not on equipment going back into service.
  
  

What is proof load testing?

Proof load testing is a specific type of load test. It applies a load above the rated capacity, then confirms the equipment carries it without permanent deformation, cracking, or failure. Passing the test "proves" there is a safety margin between the rated load and the load the equipment can actually handle.

For overhead and gantry cranes, OSHA caps the test load at 125% of the rated load unless the manufacturer recommends otherwise. Below-the-hook devices and rigging hardware follow their own ASME B30 and manufacturer requirements.

Proof load testing is non-destructive. The equipment goes back into service after it passes, along with a test certificate documenting the load applied and the results. Aldinger's proof load testing services cover cranes, hoists, rigging, and lifting fixtures.

Proof load testing vs. load testing at a glance

When do you need proof load testing?

Schedule a proof load test when the equipment's load rating needs to be established or re-confirmed:

• Before first use of a new crane, hoist, or custom lifting device.
• After an alteration, such as a capacity change, new runway, or structural modification.
• After repairs to a load-bearing component, including welding on a hook, beam, or frame.
• When re-rating equipment to a new capacity.
• When a customer, insurer, or contract requires it. Many insurance policies require documented proof testing of lifting equipment.

When is a standard load test enough?

A rated load or functional load test usually fits these situations:

• Periodic verification of equipment that hasn't been modified or repaired.
• Commissioning checks of brakes, limit switches, and controls after minor maintenance.
• Troubleshooting when operators report slipping, drifting, or unusual noise under load.
• Verifying structures and anchors, such as fall protection anchor points or equipment mounts.

If you're not sure which test applies, start with the manufacturer's instructions and your applicable standard. A qualified provider of load testing services can help you match the test to the requirement.

What standards and regulations require load testing?

The requirement depends on the equipment. These are the most common references for lifting equipment in the U.S.:

OSHA has clarified that employers must perform rated load tests on new and altered cranes, and that test reports must be kept on file where appointed personnel can access them.

Your industry, customer contracts, or insurer may add stricter requirements. Always confirm the test load with the manufacturer's specification before testing.

What happens during a proof load test

A typical proof load test follows five steps:

1. Pre-test inspection. A technician checks the equipment for visible damage, wear, and correct setup, and confirms the rated load and required test load.
2. Rigging and load setup. The test load is applied with certified deadweights or measured with calibrated load cells, and an exclusion zone is set around the test area.
3. Load application. The load is increased gradually to the required test value and held for a set period.
4. Post-test inspection. The equipment is checked for permanent deformation, cracks, slippage, or other signs of distress.
5. Documentation. You receive a test certificate showing the equipment tested, the load applied, the method, and the result.

How to choose a load testing company

The right load testing company should be able to show you more than a truck and some weights. Look for:

• Accreditation. An ISO/IEC 17025 accredited provider has been independently assessed for technical competence and traceable measurements.
• Calibrated test equipment. Load cells and deadweights should carry current, traceable calibration certificates. A test is only as accurate as the equipment used to perform it.
• Enough capacity. Confirm the provider can reach your required test load, including the 125% overload.
• On-site and in-lab options. On-site testing avoids moving large equipment; in-lab testing works well for slings, shackles, and smaller fixtures.
• Audit-ready documentation. Certificates should be clear enough to satisfy OSHA, your insurer, and your customers.

Proof load testing FAQs

What is the difference between a proof load test and a load test?

A proof load test applies a load above the rated capacity to prove a safety margin. A load test is any test that applies a known load, at, below, or above capacity, to verify performance.

What percentage is a proof load test?

For overhead and gantry cranes, the test load is up to 125% of the rated load under OSHA 1910.179, unless the manufacturer recommends otherwise. Other equipment follows its own ASME standard and manufacturer specification.

Is proof load testing destructive?

No. Proof load testing is designed to stay within the equipment's safe limits, so equipment that passes goes back into service. Break testing to failure is a separate, destructive test.

How often is proof load testing required?

Proof load testing is generally required before first use and after any alteration, re-rating, or repair to a load-bearing component. Periodic intervals depend on your standard, insurer, and manufacturer.

Does OSHA require load testing for cranes?

Yes. OSHA requires rated load tests on new and altered overhead and gantry cranes before initial use, with test reports kept on file.

Where can I find load testing services near me?

Aldinger provides on-site proof load testing primarily in Dallas–Fort Worth, Houston, and Little Rock.

Get proof load testing services from Aldinger

Whether you're commissioning a new crane, returning repaired rigging to service, or preparing for an audit, Aldinger's proof load testing services give you the documented results you need.

Aldinger offers on-site proof load testing primarily in Dallas–Fort Worth, Houston, and Little Rock, with:

• Compression load testing with load cells up to 100,000 lbs
• Tension load testing up to 50,000 lbs
• Deadweight proof testing up to 20,000 lbs

Schedule proof load testing or contact your nearest Aldinger location to confirm coverage for your area.