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Technology
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Compressed gas container
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Safety valves and
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Bursting disc equipment
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are subject to technical regulations and rules which constantly need to be adapted to the latest state of technology.
Safety valves
are valves which open automatically when the actuation over-pressure level is reached, and close again when the pressure falls below the actuation level.
Bursting disc equipment
is fitted with a bursting disc which is destroyed when the actuation over-pressure level is reached, so creating an opening.
Safety valves fitted with a bursting disc
are combinations of a safety valve with a bursting disc unit on the pressure side.
Safety valves can be:
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1.
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spring-loaded
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2.
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constructed in such a way that any jamming or sticking of moving parts is impossible, even at different temperatures; seals whose
function can be affected by friction forces are not permitted.
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In safety valves which are installed in or screwed into shut-off devices they must be
arranged in such a way that correct function is guaranteed when the container is in use. Screw-in safety valves must be secured to prevent working loose.
Bursting disc equipment must:
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1.
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be fitted with a bursting disc,
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a.)
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whose material is unaffected by the filling (also taking into account any impurities which might occur) or by an industrial
atmosphere; if necessary the disc must have a coating which can neither become porous nor split during bulging,
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b.)
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whose clamping force is created by torque wrenches when necessary
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2.
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be designed in such a way that the bursting disc has a concentric seat, can be fitted to parallel faces, and is not damaged in
pressure areas in which it merely bulges,
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3.
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be sealed tight in respect to the atmosphere until it reacts within the range of operating temperatures,
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4.
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release the necessary cross-section when the disc bursts; in the case of a disc which is supported against over-pressure, the
reduction in the cross-section caused by the support must be taken into consideration,
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5.
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be protected against the disc fixing coming loose.
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In the case of
safety valves with a front-fitted bursting disc, always ensure that:
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pressure can only build up in the space between the bursting disc and the safety valve after the bursting disc has burst,
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2.
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the function and the blow-off output of the safety valve is not affected by parts of the burst bursting disc.
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Markings
Each bursting disc must be marked as follows:
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Type approval mark if the unit is approved according to type
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2.
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The manufacturer’s name or firm’s brand; this is not necessary if the bursting disc contains the type approval mark.
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3.
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The official expert’s mark if the unit has been individually checked,
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4.
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Type designation (chosen by the manufacturer of the unit) if this designation is of relevance
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5.
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Year of manufacture of the unit – the last two digits
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6.
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Bursting pressure (rated value) in bar; however, in the case of cartridge bursting disc units for CO2 cylinders it is the
cylinder’s test overpressure, i.e. 190 bar or 250 bar
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7.
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Designation of the pressure gas for which the unit may be used
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8.
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For CO2 cylinders, an additional external colour coding
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Bursting discs must be marked in such a way that they are correctly assigned for use. In addition, bursting discs for use with carbon dioxide must be colour-coded.
Whenever you need individual components or complete bursting discs, you can rely on Wehberg Safety’s comprehensive range of perfected products. Thanks to our
tried-and-tested basic construction of these standard products, Wehberg Safety offers the solutions to almost all application situations for bursting discs.
Wehberg Safety’s superior quality standards are also characterized by the procedures which our bursting disc specialists have developed.
Bursting discs are always made of corrosion-resistant materials such as aluminium, stainless steel, nickel, inconel, monel and tantalum, as well as in connection with
corrosion-resistant plastics such as FEP and PTFE. This means that we can offer products for virtually every application.
The actuation pressure varies according to the temperature at the installation site.
As the temperature rises, the actuation pressure always falls. Different metals react differently to changes in temperature, such as inconel in combination with stainless
steel. These characteristics need to be taken into consideration when bursting discs are being selected.
The 300 mm diameter bursting disc shown below was manufactured for a group of
chemical companies to safeguard the pressure in a safety pipeline.
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The same type of bursting disc as that shown here was sent to our test
laboratory for testing purposes. Before bursting it passed all levels of our quality assurance system with the best possible test values, and could confidently have been dispatched for assembly.
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The bursting of a boiler bursting disc brought about under extreme
conditions in the test laboratory
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The tool manufacture department and the annexed construction department provide us with the direct preparation, maintenance and optimisation of
manufacturing processes.
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