Rupture disc design pdf

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The screw-type safety head has a replaceable disk. Industrial Explosion Protection, - [PDF 8 Pages] An introduction to Industrial Explosion Protection and Prevention including information on venting, suppression, spark detection, isolation and testing. It has flanged connections, a full nozzle, direct action and is spring loaded.

There are three types: Conventional, Balanced with bellows and Balanced-Piston. They are calibrated against a static Yokogawa temperature components. The other 7 tests tests 1 through 6 are repre- transmitter Model YTA Data are collected in ultra-rich gas mixture compositions shown in Table 2, calculated a block of 16, data points; hence for a window of ms, the using Peng-Robinson E.

The gas mixture composition is The aim of the chosen initial conditions, in combination with the determined by an on-line Daniel gas chromatograph. Temperature control 18 Medium Rich Gas is achieved by the heat tracer with set point at the desired gas Rich Gas temperature of the particular test. Phase envelopes of the three desired gas mixtures based on PR E. Table 4 shows the same information for of the isentrope with the respective phase envelope.

This obser- the 8 tests conducted on the rough shock tube. A corresponding trend 6. Results of decompression wave speeds was observed in earlier work conducted by Advantica involving an NPS 6 shock tube and NPS 36 fullscale rupture tests [2]. This section presents test data and the resulting decompression The next section provides an insight into this observation by wave speed of the total of 16 rupture tests conducted: 8 on the examining the one-dimensional momentum equation and pertur- smooth shock tube and 8 on the rough shock tube under the same bation theory applied to the decompression phenomenon.

The mixture compositions and initial pressures and temperatures 7. Discussion on the effects of roughness on decompression were given previously in Tables 3 and 4. Example pressure-time wave speed traces for the reference tests and Tests 3 for both the smooth and rough shock tube are given in Figs. We start with the shown side-by-side in indicative Figs. The difference For a small perturbation, i.

Pressure-time traces for the reference tests top: smooth tube, bottom: rough tube. This evaluation was conducted at 7 MPa-a, dt vt x vx t which is a low enough pressure to discern the difference between This is very close to the measured value of Pressure-time traces for the test 3 top: smooth tube, bottom: rough tube. Experimentally determined decompression wave speed vs. As was mentioned earlier, the fracture resistance necessary for The application of the TCM involves comparison of curves the arrest of ductile tearing fracture is commonly determined as describing the variation of decompression velocity and fracture Charpy arrest energy CVa using the Battelle Two-Curve method velocity as a function of pressure.

The former curves are calculated TCM [16]. This is an important consideration in terms velocity originally developed by Battelle researchers. It follows that the limiting Depending on the circumstances, the toughness determine the necessary arrest toughness for conventional designs.

Accordingly, it was lower temperatures and rich gas mixtures , more detailed analysis considered important to evaluate the potential effect on calculated is required, and is usually carried out using the TCM.

In addition, arrest toughness of changes in decompression behaviour of the since the simple formulae in AS For this reason, it is important to under- Four comparison cases were evaluated, three of which involved stand the implications, from the point of view of arrest toughness, mm OD DN pipe, and one of which involved a OD DN pipe.

In shock tube. It was reasoned that bounding the potential range of each case, the fracture velocity curve that is tangent to the theo- practical conditions would make it simpler to devise a general retical decompression curve, calculated using GASDECOM, is correction scheme by interpolation, should one be needed.

It is shown, for rough and smooth cases. Since, with the exception of realised that the surface roughnessediameter ratio of the rough Fig.

For the cases considered, the experimental estimates. For the Also conditions and methods of manufacture. For this reason, three comparisons were carried effect of the change in decompression behaviour between rough out involving mm OD DN pipe under conditions that lead and smooth cases can be assessed as the difference in Charpy energy to tangency in different regimes.

In this case, also, the data on an expanded scale, so that the intersections between experimental and predicted decompression behaviour for the fracture velocity curves and decompression curves can be distin- smooth tube was very similar, in the region of tangency. For the guished more clearly. The pipeline design considered was increased from the theoretical value of 98 J to J, an increase of a mm OD DN , X70 pipe at a design factor of 0.

In this case, the initial pressure was lower, leading to and the Charpy energy had to be increased from 45 J to 52 J an the formation of a plateau at a higher pressure ratio. X70 pipeline with a design factor of 0. While the initial pressure was similar to that Again, the GASDECOM and experimental decompression curves for of the reference tests, the rich gas composition resulted in the smooth tube were virtually coincident, in the region of a plateau towards the end of the decompression curve.

In this tangency. Reference tests, Finally, Fig. In this case, the pipe diameter has been reduced to of surface roughness on the required toughness for fracture arrest For a mm OD DN pipeline under the conditions the points of tangency to even lower pressures.

This comparison must be considered upper bound. Nevertheless, while experience has viewed with some caution, since there is some question concerning showed that frictional effects can usually be ignored in the ductile the accuracy of the fracture velocity equation for small-diameter fracture arrest design of large-diameter pipelines DN and pipe.

Nevertheless, it provides some indication of issues that may larger , these analyses indicate that it is prudent to take them into need to be considered in the fracture control design of small- consideration for small-diameter pipelines in particular, DN diameter pipelines for rich gas applications, and also indicates that and smaller.

This was related to an corresponding to a design factor of 0. In such cases, an increase in wall 3. Though this analysis was conducted in terms of the effect of thickness from the minimum permitted by standards or regulations surface roughness on arrest toughness at a constant diameter, may be required, in order to comply with ductile fracture propa- it should be recalled that frictional effects are primarily gation control requirements.

Concluding remarks should be considered in the design for ductile fracture arrest of smaller diameter pipelines DN and below , particularly The following conclusions can be drawn from the present where high pressures and rich gas compositions are involved. In this configuration, the rupture disc offers a higher standard operating ratio and better vacuum resistance. It is more resistant, more rugged and gives a longer service life.

A higher standard operating ratio allows you to operate your system under a higher load without the risk of fatigue or premature opening of your rupture disc. In forward acting rupture discs, the domed side of the disc faces away from the process system.

As the process pressure increases beyond the allowable operating pressure, the rupture disc starts to grow. This growth will continue as the pressure increases until the tensile strength of the material is reached and rupture occurs. Hence this type of rupture disk is also called as Tension Type Rupture Discs. While selection of rupture discs numerous parameters are taken into account, in order to ensure optimal function. These include, for example:. Tags: burst diaphragm burst disc bursting disc pressure safety disc pressure safety valve rupture disc.

Rupture Disc Applications Rupture discs can be used as a single pressure protection device or as a combination with pressure safety valve. Rupture disc can be used for isolating the high-cost valves from the process in case of over-pressurization, thereby saving on valve maintenance and replacement. Rupture discs can be used to specifically protect installations against unacceptably high pressures or can be designed to act as one-time valves or triggering devices to initiate with high reliability and speed a sequence of actions required.

Rupture discs and safety valves can be combined in two different configurations: Rupture disc installed parallel to the pressure safety valve. In the case of over-pressurization, if the pressure safety valve fails to operate or unable to relieve excess pressure fast enough, the rupture disc will come into action and burst controlling the pressure. Rupture disc installed below the pressure safety valve. Usually pressure safety valves tend to leak more after being triggered for the first time.

Rupture discs can be used upstream of the pressure safety valve to ensure a perfect leak proof seal. In case of corrosive, adhesive, polymerizing or viscous fluid in the process piping system, rupture disc in upstream helps in safeguarding the functionality and reliability of pressure safety valves.