Latest version of document. Guidelines on the structural design and construction of steel chimneys of circular cross-section; and the design and application of linings for such chimneys where required. Revision 2, September First published
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Construction of bedded Hospital-TechnicalSpecs. Jump to Page. Search inside document. Increase in along-wind load Basis of Design and Safety Factors 7. Increase in cross-wind response Sietetetel 7. TS Bxplosions eee eee eceteeeeeeee 7. Wind Speesi 7. Wind load in direction of the wind CICIND is no, nor ate any of ts members, be held responsi for any filure alleged or proved tobe due to adherence 1 recommendations or acceptance of information Published by the association in 2 Model Code or in any other way.
Fatigue suength. Infivence of high temperature.. Inemal covvasion allowance Bearing on connected surfaces Structural flanges and opening reinforcement Stiffening rings WS Base plate Surface Protection Guyed and Stayed Chimneys Berger Germany J.
Ghermandi Italy S. Ole Hansen Denmark G. Pinfold Great Britain RM. Warren Usa. Expert advice was received from: BL. The design of stee! The construction and erection should be carried out by firms competent in this class of worle At all times the work should be under.
Further revisions of this model code will therefore be published from time to time. Appendices and Commentaries This Modet Cod: is accompanied by extensive appendices and commentaries. It does this by comparing th probabilities of failure for given safety factors during its design lif with the failure probabilities required to satisty accepted social an economic criteria. It also relates to chimneys with aheight less than 15m anda slendemess ratio more than The model code does not deal with architecural or thermal aspects of steel chimneys nor with their foundations, except insofar as they affect the chimney's structural design.
The model code does not deal with those aspects of the design and constuction of steelwork, refractories and insulation which are not peculiar to chimneys. Additional information is Commentaries, a in the Appendices and S. Zurich, Switzerland  Schulz, U. The limit stress is defined as fither yield stress of critical buetling stress whichever is Teast divided by the material safety factor.
Typically chimneys in industrial sites, pawer plants ar chimneys fess than m tall im urban locations, where any domestic dwelling is ouside the falling radius of the chizaney , 5. Limiting sess ranges are given for various weld classifications and design Lives, In addition toa rasecal safety factor 1. This init will be govemed by the prominence and visibility of the chimney and the frequency with which maximum amplitudes can be expected.
Guidance is given in Commentary 3. Special steels can be used providing that they are precisely specified and that their characteristics, snch a8 yield stress, tensile stenath, ductility and weldability, enable the Model Code to be put iaio application.
In zones where bearing elements are subjected to tension, a5 a result of extemal loads or in zones of three-dimensional stress, the ductility requirements, in addition to the minimum stengts values, shall be considered. Structural Steels 6. For the most commonly used grades of steel, Fe , Fe and Fe , Table 6. The limit suesses of steel aze equal to the yield suess of the steel used, divided by dhe material factor 1.
The yield stresses at high temperatures are sven in Table 6. Youngs modulus: see Table 6. Cp i applied 10 the outer diameter of he chimney in the vaned parton and not the outer dimension of the vanes. For attchments, including ladders, etc. Typical lenges and widths of Tncder members have been takes ime account. No significant movement due to vortex shedding willbe found if the critical wind-speed exceeds 1.
A major dewrmising propery is the dimensionlest "Seruion number" defined as: Som Armas 78 padi? Ifthe Scruton mumiber is less than 5, eross-wind oscillations could ba violent.
The addition of stabilisers or damping deviee see Ovalling Jn most cases, a suitably sized siffening ring atthe lop of a chimney will eliminate problems associaied with ovalling 7. Note the assumpriow that 5 see gust windspeed mls ac height ze 14 V 2 is safe ar al heights 7. Cade 7. The increase is not yes fully understood, but is dhought to be due to Increases in bod Lif coefficient and negative aerodynamic damping.
Note that aerodynamic suabilisers e. Lald for aa between 10 and 15, For 2 spacing ravio ald tess han 10 there is a risk of very large increases in emplituds. This etn be important inthe design of a toned mass damper, Fig. Care mus be taen wo include forthe effects of any supporting structure. Assuming a chimney ison a rigid support, its first nameal frequency may be calculated by dividing it into 2 suitable numberof setions wsing the fommula fr the fist mode Ay 12m.
Several options are available to the designer. The pileh of the vanes should be 3D. The extra wind drag dveto the Vanes must be considered See Damping devices Damping devices are attached to a chirmmey to increase its strucrurel, amping, thereby signficanly reducing the eross-wind and along- wind vibrations, including the eifecs of aerodynamic interference by atber nearby towers oF chimneys.
Code 7. Fowte special chimney designs end damping devices may prove cefiecive in preventing excessive wind induced. These Should have been proven inislly by wind runrel tests and fnally by field experience before being universally adapted.
Guyed chimneys must also be sibject to special investigation 7. In addition, the resulting. Explosions, Internal explosions Internal explosions can occur due to the ignition of soot ar explosive gut in te chimney, They are not normally a cause for concer in the design of a steel chimney. Internal effects governing the chimney design 7. Tis is especially So with gas turbine exhausts, where levels of excess air can be greater than thase normally experienced.
Chimney fies can be causes by ignition of 1 Unburned fuel cared over fram the sssociated boiler or fornace, 12 Where the associated furnace is in pettochemical service, unbumed hydroearnen canyover following a furnace tube rope.
Typically, a castable refiaciory lining Following the equirements of Appendix 3 will provide suficiest fire protection for mast situations, 7. For unstifened chimneys Le. Similarly, this will lead to increases in tensile Sieesses at the base and immediately above a change in chimney diameter, which will be important in deriving bolt tensions. Carrying capacity of shell 8. Nevertheless, occasionally movement amplitude may be sufficient to cause alarm.
In such cases the araplitude limitation of Section 5. Unless more detailed results become available dhe modelling safety factor shall be increased to 1. Interoal Sanges hall have corrosion allowance Cl and external flanges corrosion allowance CE an all exposed surfaces. The allowances listed in wbles 8.
Model code for steel chimneys. The CICIND chimney standard
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International Committee for Industrial Construction
cicind - model code for steel chimneys_1999.pdf