HOW IT WORKS

The Rupture Pin valves relieve pressure at set point with predetermined accuracy and dependability. The valves consist of a piston on seat, restrained from movement by a slender round pin known as the buckling pin. The piston and seat have a bubble-tight seal while under pressure. The pin will buckle at set point from an axial force applied by the system pressure acting on the piston. Each valve is self-contained and self-actuating. When the pin is buckled, the valve is full open in a matter of milliseconds. The pin is external to the system being protected and is tightly held in place at both pin ends.

EULER'S LAW OF COMPRESSED COLUMNS
Euler’s Law determines the buckling point of the Pin.
 

By using Euler’s Law of Compressed Columns, the pin's diameter, length, and material can be determined and the set point accurately predicted, every time.

The pin dimensions must be precise; we control the pin diameter by measuring to 5 decimal places and the length is measured to 4 decimal places, insuring the necessary quality control and set point repeatability. The modulus of elasticity of the pin material is the only variable due to ambient temperature. Using materials that have a minimal change in modulus of elasticity in the temperature range where the valve will be in service solves this challenge.

Because the pin is in compression, pulsation is not a factor and the pin can never fatigue or fail prematurely. Since the pin is external to the system, pin corrosion in not a concern. A corrosive environment outside of the system you are protecting is no problem since the pin is made of a non-corrosive material.

MULTIPLE CAPABILITIES
> There are no limits to valve size or set points. Rupture Pin valves have been successfully built as small as 1/8th of an inch to 48” diameter. Pressure set points can be set as low as 2 inches of water column to as high as 100,000 psi. Vacuums can be set as low as 1 psi.
> Rupture Pin and Buckling Pin valves can be designed to sense system pressure or differential pressure, unlike rupture discs, which can only sense differential pressure.
> Rupture Pin and Buckling Pin valves can be designed to handle corrosive and dangerous fluids and gases with minimal operating expenses and no environmental concerns, because the systems’ integrity is not compromised when resetting the Rupture Pin or Buckling Pin Valve.
> Rupture Pin and Buckling Pin Valves can be made of special alloy materials, plastics or be glass lined to meet your unique situations.
> The valves may also be equipped with a proximity sensor to alert the operator of a valve opening.
> The body of a Rupture Pin relief valve can also be a quarter-turn ball or butterfly valve. In all types, the valve goes to a full open position in only milliseconds.

VALVE CERTIFICATION TESTS
Certification tests are done on all valves before they leave our facility. The ASME standard calls for set point variation of +5%, but rarely is the deviation over +3% from set point; +1% is common. After successful valve testing, three pins are tested on the Tinius Olsen machine to determine a load vs time curve for the archives. This insures consistency between pin material lots.

Special machines are used to cut the pins to length perpendicular to the pin axis and polish the cut ends. All pins are tagged with all pertinent information required to match the pin to the valve. All valves have a serial number stamped on the bonnet and valve label. New pins may be ordered with just the valve serial number. Pin orders before noon on business days can be shipped to you on the same day.

APPLICATIONS
> The Rupture Pin valves have many uses where a non-resetting pressure relief valve is desired.
> Any place you are using a rupture disc, the Rupture Pin relief valve will save you operational expenses and eliminate environmental concerns.
> The Rupture Pin valve will give you an immediate visual indication that you have had a relief action without the need to disassemble your system – as you would have to do with a disc, where broken disc indicators are not reliable.
> You can reset the Rupture Pin valve in a matter of minutes and be back in business.
> You will be able to operate your system closer to maximum operating pressures without the fear of premature failure associated with rupture discs.
> We have also found that operators are replacing many of their resetting relief valves with our Rupture Pin Valve because of the problems associated with mandated yearly valve tests. Spring loaded relief valves will leak near set pressure and pilot operated relief valves get plugged and will give you a false sense of security. The Rupture Pin valve will give you a bubble-tight seal until the pin buckles. Unlike spring loaded relief valves, Rupture Pin relief valves give full opening port at set point.

HIGH PRESSURE RELIEF SUCCESS
We have success with high-pressure relief situations with our Model “H” and Model “I” Rupture Pin Valves. The oil industry offshore production platforms have chemical injection systems that operate at pressures as high as 15,000 psi. We have Rupture Pin Valves doing system protection on these chemical injection systems with a high level of confidence. These valves are operating within +3.0% of set pressures while keeping a bubble tight seal until buckling at set point. With the option of storing the replacement pins on the valve, operators are very pleased with the space savings and convenience of our valve. Special “I” valves can give full port relief at pressures as high as 100,000 psi.

POSITIVE DISPLACEMENT PUMP SUCCESS
Our Model “I” valve has many successes working with systems that have positive displacement pumps. The rupture discs will constantly flex due to the pressure pulsations and will constantly fail early. Shear pins also fail prematurely. With the Rupture Pin Valve, the pulsation is not a factor, because the piston transfers the pulsation to the Pin in compression. When the Pin is in compression, it cannot fatigue because the Pin buckles by Euler’s Law instead of Pin material failure.


SUMMARY
Several features of the Rupture Pin valve should make it your first choice for system protection. The Rupture Pin valve is not subject to premature failures. It is much more accurate that anything else on the market, especially at extreme pressures (low or high). The pin is independent of system temperature and corrosion factors. It offers you flexibility and protection. If you have backpressure on a relief system, the Rupture Pin downstream balanced piston solves the problem.

The Rupture Pin valve will offer substantial savings in operating and maintenance cost by avoiding premature failures, not breaking into the integrity of your system to reset, not exposing you to environmental concerns, and quick resetting when you do have to change the pin.

Our customers have found the initial cost slightly higher than rupture disc and conventional pressure relief valves, but in terms of ease of use and cleanliness, the Rupture Pin valves have proven to be a better overall value for solving problems.

For additional information on the Rupture Pin or Buckling Pin Valves, or specific answers to your questions, contact Lee Levisay at 405.789.1884 office or 405.830.0776 mobile.



VALVE MAINTENANCE
There are two ways to check the piston movement.
(1) Remove the pin and apply pressure to the valve of no more than 10-20% of the set point. If the piston moves, the valve is in good shape.
(2) Turn the pin holding nut one turn, no more. If the piston moves, the valve is in good shape. Tighten the holding nut. You are now assured of opening at set point. The pin is never a concern. It obeys Euler’s Law. If the piston does not move, remove the top assembly by loosening the bonnet bolts.
(The top plate should never be removed). Remove the piston and replace the elastomer seals; reassemble and reset the Pin. Check to make sure the pin is not damaged or bent by rolling on a flat service, the pin will have an infinite life if not damaged or bent.