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TRYBAR

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DETAILED PROOF TESTING


Ensure the integrity of pipes, cylinders, and tanks with pressure and proof testing from our company. Trybar offers pressure testing services for an extensive range of pressures, from relatively low (a few psi) to very high (up to 200,000 psi). We offer both low-pressure testing services and high-pressure testing services. We can test up to 200,000 psi with liquid, up to 30,000 psi with nitrogen or helium, and up to 6,000 psi with air. We maintain a range of electronic pressure transducers to cover virtually all pressures. These transducers all have a current calibration certificate traceable to NIST standards.

The instrumentation we use varies according to the needs of the job in hand, ranging from manually recording data to high-speed, multichannel computer-based data logging. Many tests can be documented with a simple chart recording of pressure vs. time. We have pressure tested items varying from glass chemical vessels (7 psi) to special distribution manifolds (170,000 psi).

Proof Testing

A nondestructive test, proof testing verifies that a component or system is capable of withstanding a pressure slightly above the design or operating pressure without permanent damage or leaking. Proof testing is like a "stamp of approval."

Leak Testing

Really a form of proof testing, leak testing requires that the part be pressurized and checked for leaks. Often, this is done by immersing the part in a clear liquid (usually water), pressurizing with air, nitrogen, or helium, and watching for leaks.

This is a simple and versatile test. A stage further is to use helium and a mass spectrometer device to check for leaks. This is very sensitive and provides a quantitative assessment of any leak, but it requires extensive fixturing.

Burst Testing

A destructive test, burst testing establishes the pressure at which the component or system sustains permanent deformation, and finally the pressure at which it fails. It also establishes how it fails — by leaking, catastrophic failure, etc. Burst testing is the ultimate design check. (You make it, we break it!)

AUTOFRETTAGE

The fatigue life of thick-walled, high strength, high-pressure components can often be substantially improved by an initial pressurization high enough to yield the bore area. This process takes advantage of the stress variation across the wall of a thick-walled cylinder: the stresses are much higher at the bore than at the outside. As the pressure is increased, there comes a point where the material near the bore yields, but the rest of the wall is still elastic. When the pressure is released, the material at the bore winds up with residual compressive stresses, which can substantially improve the fatigue life under cyclic loading.

Pressure Gauge

External Pressure Testing

Occasionally an item must be tested with external pressure, such as parts that are to be used subsea. External pressure testing is much more difficult, especially for large parts, because a pressure vessel has to be used that is big enough to accommodate the part and has a removable end so that the part can be placed inside the vessel. We have a limited capacity for external pressure testing, but we are always willing to look at adding capability to accommodate new test requirements.

Transient Pressure Testing

We can measure transient pressures up to 100,000 psi using quartz transducers and charge amplifiers. These devices have very high response speeds. They are used to measure pressures that change very rapidly, such as gun barrel pressures, chemical reactions, pump transient pressures, etc.

Strain Gauge

Strain gauges are small, flat, highly specialized electrical resistors that are glued to a surface. When the surface of the test piece or structure stretches, the strain gauges change resistance in proportion to the stretch (strain). This very small change in resistance can be measured, so that the strain (change of length divided by the original length) can be measured. The corresponding stresses (force divided by area) can be calculated from the strains using basic properties of the material being tested. This information from a pressure test can be used to determine at what pressure the test item passed its elastic limit and started to yield.

Fitting and Fixture Design

Many tests require custom fitting and fixture design to seal components and assemblies that are tested outside their "natural environment." We carefully design these fixtures so that they attach to the test items in a realistic fashion, accurately simulating real-world forces, and without creating unusual stresses and stress concentrations.

Temperature

We can test in a temperature-controlled cabinet from -100οF to +525οF. The inside dimensions of the cabinet are 11" x 20" x 14". In addition, we offer high pressure, high-temperature testing.

Extreme Pressure Fluid

Now available from Trybar: EPF 262 Extreme Pressure Fluid in one gallon, 5-gallon or 55-gallon sizes, for use to 200,000psi. Ordinary hydraulic oils begin to solidify at about 80,000 psi. Other fluids can be used at much higher pressures, such as brake fluid and "white" gasoline (Coleman type for camping stoves). However, brake fluid is not compatible with most seal materials, and is unpleasant to work with. White gasoline is highly flammable. EPF 262 is a well-proven fluid suitable for high pressures. 

All tests performed by Trybar, from the lowest to the highest pressure, from the simplest to the most complex, are carefully planned and executed. Test certificates and reports are supplied with each test. At Trybar, our best work is done "under pressure."


Case Study:
Thin-Walled Titanium Pipe

Before Thin-Walled Titanium Pipe Test After Thin-Walled Titanium Pipe Test

 
A high-strength, thin-walled, titanium pipe was tested to determine the burst pressure, and the longitudinal and circumferential stiffness. The chains were used as a safety precaution in case the end fittings blew off. The challenge was to seal the ends of the tube without welding, which could affect the material. The wall was too thin to thread, so we designed end fittings that could be glued on, resulting in no damage to the material and no stress concentrations. The fittings were designed to accommodate the anticipated end load of 210,000 pounds at burst pressure. The pipe was strain gauged using eight gauges to provide the information needed to calculate the stiffness.

Case Study:
Thick-Walled Steel Tube

Before Thin-Walled Titanium Tube Test After Thin-Walled Titanium Tube Test

 
A thick-walled heat treated steel tube was strain gauged and burst to determine the elastic limit, the burst pressure, and the mode of failure (ductile or brittle). The strain was recorded up to the maximum pressure of 115,000 psi.