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Expansion Joint Product Testing: Hydro-Testing

Objective: The objective of this test is to check for leakage or cracks in the welding.
What We Do: The bellows is completely filled with a liquid such as water. Pressure is slowly applied to the liquid until the required pressure is reached. This pressure is held for at least 30 minutes at which point the component is inspected visually to locate leaks.
Completion: If a leak is present, the welds will be repaired after releasing the hydro test pressure.

Bellows are pressurized	Pressure is observed

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Expansion Joing Product Testing: Dye Penetration Testing

Objective: This test is performed to insure there are no weld defects such as surface cracking or weld discontinuities before and after forming the bellows.
What We Do: The weld surface is thoroughly cleaned and a red penetrant dye is applied to the surface of the weld and allowed to soak for a period of time. The dye is then removed and a white powder is sprayed on the weld surface that performs a blotting action.
After Completion: An indication of the dye with a white background characterizes the weld surface discontinuities of the bellows longitudinal seam weld. This testing before and after the bellows forming process ensures a sound quality bellows seam weld.

 

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Expansion Joint Product Testing: Fatigue Testing

Objective: The objective of the fatigue testing is essentially to verify how many cycles a bellows can withstand before failing.
What we do: The bellows is placed on the “cycle-test machine” and bolted to a hydraulic plunger. Each cycle is counted as the bellows is compressed and returned to neutral.

Fatigue Testing / Cycle Testing Video

This video shows an expansion joint bellows being subjected to a cycle test as required by the customer. The expansion joint is compressed and expanded through its specified design movement of 1 and 1/4 inches to verify the calculated lifespan of 30,000 cycles. The number of completed cycles is recorded throughout the duration of the test.

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Pipe Expansion Joint Product Testing

U.S. Bellows, Inc. does extensive physical testing ranging from X-Ray tests and Hydrotests to Helium Leak tests (using a mass spectrometer.) Each bellows and pipe expansion joint unit goes through in-process quality control using a system of travelers. Final in-house inspection and testing are performed prior to shipping. Our manufacturing shop also has ASME Section VIII CODE certification.

Fatigue Testing (also known as Cycle Testing)

Fatigue testing is essentially verifying how many cycles a bellows can withstand before failing. The bellows is placed on the “cycle-test machine” and bolted to a hydraulic plunger. Each cycle is counted as the bellows is compressed and returned to neutral.

View a Fatigue Test Verifying a Cycle Life of 30,000 (VIDEO)

Burst Testing

The objective of the burst test is to determine the ultimate pressure resistance, primarily conducted on bellows. Normally, hydraulic pressure is slowly increased until failure occurs. Pressure balanced pipe expansion joints are designed to maintain a constant volume through the use of a compensating bellows.

Dye Penetration Testing

Liquid dye and a white powder observant are used to locate leaks or cracks in the bellows attachment welds. This test is performed for long seam welds before and after forming the bellows.

Hydrostatic Testing (also known as Hydro-testing)

During a hydro-test, the bellows is completely filled with liquid until a desired pressure is reached. The bellows is pressurized for 30 minutes to locate leaks or cracks in the welding.

Helium Leak Testing

The bellows is filled with pressurized helium and then “sniffed” to detect leaks indicated by a mass spectrometer.

Additional Product Testing:

• Ultrasonic Testing
• Radiography Testing
• PMI Testing
• Pneumatic Testing
• Magnet Particle Testing

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Expansion Joint Product Testing: Helium Leak Testing

Objective: The objective of the helium test is to locate and calibrate leaks.
What We Do: The unit is filled with pressurized helium and the outside is “sniffed” to detect leaks which are indicated by a mass spectrometer.
After Completion: Once the test is completed, leak areas can be passed, rejected or repaired.

Helium Leak Test Being Performed on an 18″ Diameter Stainless Steel Single Expansion Joint

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Expansion Joint Product Testing: Burst Testing

Objective: The objective of the burst test is to determine the ultimate pressure resistance that a bellows can absorb prior to failure. Burst tests help determine the margin of safety and safety factor to be used in a specialized bellows design.
What We Do: During a burst test, hydrostatic pressure is slowly increased until failure occurs, which usually happens in one to two hours. Burst testing is conducted at ambient temperatures to determine a bellows pressure rating. We follow all the necessary safety precautions for personnel involved, such as placing the bellows in a high strength steel cage and using a safety shut-off switch.
After Completion: Based on the burst test results, a safety factor is applied, thus establishing the ultimate pressure rating.

Burst Test to 800 psig on a 304 Stainless Steel Bellows	Q.C. Inspecting the Bellows After a Burst Test

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