Bellows Manufacturing and Research, Inc. | Testing

Metal bellows enable effective functionality in a wide variety of sensors, seals, and fluid-handling applications. From aerospace to biomedical processing and power generation, a range of industries relies on these precision components to meet their exacting performance demands in often less than ideal conditions. Whether customers are dealing with extreme temperatures, corrosive environments or time-sensitive processes they need assurance that their bellows are designed and manufactured to the highest quality standards.

The stringent testing and QA processes in place at Bellows Manufacturing and Research, Inc. ensure that each product delivers excellent performance across a wide range of metrics including stroke, pressure capacity, spring rate, temperature responsivity, durability, and expected lifespan.

TESTING CAPABILITIES

BMR’s in-house real function testing capabilities represent a clear advantage over other industry competitors, with the ability to examine critical bellows parameters involving internal/external diameter limits, tube length, dynamic internal/external pressure, axial movement, working temperature, and velocity. Unlike other engineering firms that rely solely on CAD-designed 3D models and statistical analysis to determine real-world performance, BMR tests these attributes under the specific conditions and environments that they will be utilized in the future. This gives BMR a complete understanding of the practical science underlying the design and production of each advanced metal bellows.

BMR has implemented testing methods that support comprehensive structural testing on each design.

TESTING TYPES, ENVELOPES, AND SIZES

BMR Group is well-equipped to perform comprehensive bellows testing for all types of metallic bellows, from stainless steel components to various compositions of alloy materials such as Inconel, Monel, Titanium, and Hastelloy.

Currently, BMR has the ability to test bellows that are half an inch to 36 inches in diameter, while the test stands can test to pressures of up to 25,000 PSI or loads of up to 10,000 pounds. The BMR multi-pipe test stands can act independently conducting simultaneous testing. The bellows testing software used for these processes are developed in-house to provide additional production flexibility. This intuitive software can be used to convert R&D test stands towards manufacturing processes and vice versa.

TESTING METHODS

BMR’s purpose-built test stands can execute an array of destructive and NDT (non-destructive tests) depending on the customer’s specific testing needs.

RADIOGRAPHIC EXAMINATION

When customers require additional assurances of the reliability of welds, particularly fusion welds in components that are of the same thickness and material, BMR has the capability to perform CR (Computed Radiography) as well as conventional XRAY tests to evaluate whether there are any imperfections, discontinuities, or irregularities along the longitudinal and circumferential welds. This process must be undertaken before and after the bellows are convoluted. Moreover, BMR staff are certified to NAS410 specifications.

LIQUID PENETRANT EXAMINATION

The surface-level imperfection of a longitudinal and circumferential weld can indicate an accepted or rejected part. BMR follows ASTM E165–95 and ASTM E1417, conforming with AWS D17.1 and AWS D17.2 class “A and B” guidelines to perform a liquid penetration inspection of the metal surface. In this process, a two-part dye and developer application is used to indicate hairline cracks, pinholes, rolled over bead crowns and other weld defects in the bellows. For both radiographic and liquid disciplines, work is performed to the ASTM specifications and per customer requirements.

METALLURGICAL EXAMINATION

BMR has significantly expanded its knowledge base with added capabilities into the metallurgical analysis in conformance with AWS D17.1 and AWS D17.2 class “A and B” that identifies any defects of the material and/or structure. This industry standard process validates customer approved welding schedules for both fusion and resistance welding processes and confirms the accuracy of deliverables per specification at a fundamental level. The process is simple and repeatable.

A water-cooled abrasive saw provides a precision sectioned sample which is preserved in a press mounted mold to allow for consistent polishing. A semi-automatic polisher assures no variation of surface finish by regulating the speed, pressure and time during polishing. Chemical etching exposes the grain structure of the material as well as weld nugget.

A BF/DF stereomicroscope equipped with image capture and precision measure capability guarantees the integrity and traceability of the weld sample. In-depth reports produced as a result of the measurement and image capture features of the microscope safeguard the authenticity in the final reporting analysis.

MASS SPECTROMETER EXAMINATION

This is one of the most sensitive forms of leak detection testing. BMR employs this method to detect irregularities on any welded component, from large systems to tiny, individual parts. It is most commonly recommended for explosive parts. A 1+10-9 cc device is used to perform vacuum leak detection. If any leaks are detected, the specific problem is highlighted, and the weld is redone. All testing devices are located in close proximity to welding stations to encourage more effective reworks and all-around faster production.

BURST CHAMBER TESTING

Burst tests are applied to determine the ultimate pressure resistance of the bellows. A 15,000 PSIG hydrostatic pump with a testing capacity of 60” is employed for this purpose. Hydrostatic pressure is gradually applied to the bellows using water or oil until failure occurs, based on these assessments a safety rating can be applied .

For general-use applications, tests are performed under ambient temperatures, but more specific conditions may be utilized for high-temperature service equipment.

LIFE CYCLE TESTING

All life cycle tests are carried out in conditions that closely replicate future use-case scenarios. Testing gives production teams a defined point for the number of cycles a component can complete before failure. During the life cycle test, BMR examines critical functional areas through a variety of specific tests.

• Fatigue Test – Measures the bellows ability to withstand a specified number of flexing (compression/expansion) cycles. An upper limit is set based on material properties, spring rates, and safety rating.
• Spring Rate Test – Measures the amount of force required to deflect the bellows by at least 1 mm. Weights are applied up to the maximum axial compression limit of the component; the resulting length is then recorded and measured against the theoretical value. Spring rate must be within 15% of theoretical value.
• Squirm Tests – To determine the amount of pressure that needs to be applied in order to create structural instability in the bellows. Bellows are tested in both the horizontal and vertical positions.
• Hydrostatic Rupture Tests – To determine the amount of internal pressure which will cause the component to rupture.
• Bellows and Hydrostatic Vessel Pressure Cyclic Testing – from 0-15,000 and back to 0 within a specified time frame.

CUSTOMER-SPECIFIC TESTING

Bellows Manufacturing and Research, Inc.’s processes are driven by the belief that product quality can only truly be assessed in terms of the customer needs. BMR Group’s in-house test stand software gives unprecedented control over the design and development of tailored experiments that can better serve customer quality requirements. All software revisions made for these purposes are recorded so customers can gain first-hand insight into where specific implementations have been changed to answer more specific concerns.

BMR can also expand its testing capabilities by developing and fabricating new testing equipment, to meet customer demands. The production team is experienced and capable of making changes to older test stands or designing new stands to test for new quantities or a wider range of bellows dimensions. BMR Group’s in-house CNC machine shop and Tooling Department also allows the development of new part-specific testing tools.

DATA STORAGE AND USE

BMR records and stores all test data in an on-site server. Records are also duplicated and backed up to a secured offsite facility to ensure maximum data integrity. These records are deliverable to the customer upon request. Test data includes Time, Load, Video, Pressure, and Displacement or Angle.

This comprehensive storage system can also be leveraged to perform post-processing on all testing data. Customers can make use of these capabilities to request graphs, reports and other vital statistics relating to testing for specific components. Post processing is done using a proprietary Python application.

Along with the valuable data, BMR records a synchronized video of the test. The video starts as soon as the testing procedure begins, creating a real-time archive of the process.