For the design of oval and rectangular bellows the EJMA code only The inside diameter (inches) of the neck is equal to the neck outside diameter minus twice the wall thickness. The neck of a bellows is located on both ends of the convolutions and is used to attach mating parts. 0000001616 00000 n 0000001016 00000 n Additional welded-metal bellows design features: Design characteristics: Key to consider is not just the bellows seal head assemblies, but also the cartridge seal designs. The analysis indicates that the stresses at the welds are predominantly bending stresses, but increasing tilt angles lower these bending stresses. The flange neck diameter is typically 75% of the convolution outside diameter (Column 3). This separation is required to insure that each expansion joint is able to function as intended and not be affected by the flexibility characteristics of adjoining units. One movement cycle occurs each time the expansion joint deflects from the installed length, to the operating temperature length, and then back again to the original installation length. WebSpring rate [pounds per inch (lbs./in.)] But, when the strength is obtained by using a stack of separate, individually flexing thin leaf elements, the spring rate is well within desired limits. Overall length equals the convolution free length plus both neck lengths. NASA Technical Memorandum A series of convolutions is then stacked and welded at the outside diameters to form the bellows capsule. c-pfk7lwcE6P]'Z'LJ+F!#Ta?eT`P&:.4 X$ZF j(7u(SZ ?8 y/V_R##J$KSc'6wAEHxtp[_.CTyXqeiaAFM:^ap9c@~M?X(@M h=HEFn4x-]]yL$@zk]Ky"\uQ>TMB "0G7NCh6(|nzU#T8#? Main anchors are intended to anchor the pipe from motion in any direction. wF1FFCl.Z% ]!6@ s\ endstream endobj 113 0 obj <>>> endobj 114 0 obj >/PageUIDList<0 692>>/PageWidthList<0 612.0>>>>>>/Resources<>/ExtGState<>/Font<>/ProcSet[/PDF/Text]/Properties<>/Shading<>/XObject<>>>/Rotate 0/TrimBox[0.0 0.0 612.0 792.0]/Type/Page>> endobj 115 0 obj <> endobj 116 0 obj [/ICCBased 135 0 R] endobj 117 0 obj <>stream are a core sealing technology whose installation has grown dramatically, as use expands to a variety of innovative sealing technologies such as high temperature-, non-contacting gas lubricated- and corrosion- resistant seals. 0000110428 00000 n Spring The convolution free length is the free relaxed length (inches) of the convoluted section of a bellows and is measured from the outer faces of the end convolutions. The nominal outside diameter (inches) of convolutions is inversely related to spring rate (an increase in outside diameter will reduce the spring rate) and the design tolerance is used to vary the spring rate. 0000002494 00000 n Calculation of bellows spring rate In general all bellows will be calculated by the manufacturer according to the EJMA code. Note: that P1 is the flowing pressure and is in absolute pressure units. Wall Thickness (inches):0.0046 Other neck configurations are available for customized products (see Neck Types below) and neck lengths are based on customer specifications. Spring rate [pounds per inch (lbs./in.)] 0000010578 00000 n 0000042930 00000 n 3 0000087879 00000 n 0000003709 00000 n Login Register. ^wi^vL*i4 HT,=6M;MBh==4A8D} i;]ajvWZtv"XLI6m:VP~FC Mt-2g0>rVh#S@,C!Q8"m7n.. 3.3.1 Expansion Joint Stiffnesses - Little P.Eng. Threaded flanges may be added to the threaded end compensators if a flanged connection is preferred. UNREINFORCE BELLOWS DESIGN CALCULATION See . Pricing & Discounts trailer <<34AAB7DF68CE433082D5460068FC1437>]/Prev 467905>> startxref 0 %%EOF 177 0 obj <>stream This code is well proved for circular bellows. 0000011179 00000 n Traces of gas, which then penetrate through either a break in the weld or a material flaw, are immediately picked up by the sensing probe and the seal is rejected. Please contact Mini-Flex engineering staff for information on customizing products or if further clarification is required. Over 200 global locations. = D@z3g25cyN:saWsEFN{!z L3oT2yP$>\I+d#`1)P[9s8%IXcPChz.&*VJ f=Zs9+g'x)y\ BELLOWS DESIGN CALCULATION - American BOA Inc. 0000013308 00000 n 0000092397 00000 n 2023. The maximum deflection in compression is defined as the maximum compressed movement (inches) from the convolution free length position (Column 7) that will not result in permanent deformation of the convolutions. This is especially critical in high-temperature and poor-lubricating environments. The neck diameter (inches) is based on tooling but can be modified by expansion or contraction. f^@"Lr? Covers also provide a suitable base for 0000097121 00000 n This change would then become the bellows neck. Increasing the number of convolutions will decrease the spring rate and squirm rating and increase the maximum travel and length. ;_O4QK=6O-|xn|@wP/n7N]PKw6`S19`t%[@;[-ga[l}K5:{Dz|0jfF!"A Authorized Users receive OEM or Distributor level Bellows Assemblies CAESAR II computes the other value using this equation. HtVK%9)d9,s?MeKk=mJ=~l+h#; z%VbRwo5:I Y]%e??Ns_#R=?W :z)is_%x^gTAVkG3'zEt;e5GzH(stT Q 3Z1\doaho;{r9D~hJ. 'GaN% 0000096855 00000 n It is important that state-of-the-art manufacturing processes are used to create the bellows to ensure weld integrity by preventing excessive root gap with bead geometry, bead thickness and roll-over control (Figure 3). 0000004797 00000 n Transverse motion which is perpendicular to the plane of the pipe with the expansion joint ends remaining parallel. external insulation to be added over an expansion joint. Less heat improves face stability and narrow faces are less susceptible to coking than wider faces. For assistance contact us at (805) 644-1474. 0000007844 00000 n Contact Our Professional Engineers for a FREE QUOTE. The recommendations given for pipe guides represent the minimum requirements for controlling pipelines which contain expansion joints and are intended to protect the expansion joints and pipe system from undefined external forces which could cause system failure. 0000110938 00000 n %PDF-1.6 % stream Web3. Stock bellows are usually rated at 30% to 50% of the H1ay]f7@W-#,cuxW)xc,dUq&M_v{)X0P+D~w%vPu,M6kQh\~S>A2%ufgfPJhZuFffMh>c_9VP (jEVB5 QkudTc\z+%}Y~fJ{kuguT{1!ve&sdv3;{BeyEu t.\+Wc1w;KT\6F Volume (V) in cubic inches equals effective area multiplied by length. 0000043009 00000 n 0000001981 00000 n o. wG~M:3RiQ'2xr)i}f\Ax>o]%xy1 Higher critical squirm pressure ratings are more desirable when bellows function is critical (greater critical squirm pressure ratings result in increased safety factor and longer bellows life). Metal Bellows Design Guide - Thomasnet Innovation and service to help you succeed. In a nesting-ripple configuration, all the plates in the bellows are identical and contoured to permit nesting when compressed. The effective area tolerance is representative of the variation in the convolution outside diameter (the convolution inside diameter is fixed and cannot be modified). Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. For more info about our engineering services specially our piping stress analysis, please contact us and our pipe stress engineers will help you. (Note that torsional stiffnesses are not usually provided, since unprotected expansion joints are not designed to carry torsional loads and may fail catastrophically if inadvertently exposed to even moderate torsional moments.). ~xR$*:H}ms-Od~+p_5R)sP[L(5[jbsx~wb2}isKoXN s$K3EjQ$4MpA5@>?wpG`SAB-g^N)V$UY8Jl9_ =( e ^MjRma+rRk4{%;ma1kP>j &:A""/YP1IXA For maximum life, always work in compression. 0) h`K YI ;:KU^x r^^Rcz?(|g. ]c{|b= xt2nl,mL[69?82 |[yME`e-@6f&"lE. endobj >\5kv0p M!U1p?O"EC91M K*.FREg@ j/X$sffYjQhH\/U@(Z\O5eML^2,8SP!4mI8HMx@,)G[AyuR'EIj_` XO86-}39 The behavior of a bellows under load is described by the following HTr@ar@dQSu"EaHrbo}E$LB>{[T_el _Y weD =l2O@u"@jI& $dFwx]5p)x54Se8Q"BCihwbV&!O1u3`b/]Lq=;wGGyd2m`8hhAwP=K9e8d'+Z$0/tSBxlo for Engineering Services is ready to help you across Canada, USA and Arabian Gulf Area. Bellows volume capacity (less the neck inside diameter) is effective area multiplied by the convolution free length (L): V=AL. V02* EJMA Standards - EJMA !W_ /w$*#uzdO\ HWiTSgI 8SEGg#H!Y*e Y$%KGM.j@YlxLMpBRcR Dmtphso=]90BD r *P3@ d:p ~X4;9WNFVWo\k~W.P@ 't&2ijPZ*ZB\Gsf8W{xb There is a difference in terms of how the two models are entered. WebWhat We Do. Intermediate anchors can isolate multiple expansion joints that are installed in series to accommodate large motions beyond the capability of a single expansion joint. (Ae) External Effective Area (square inches) Fifty-fifty balanced seals are able to handle reverse pressure which is an upset condition that may occur in dual seal operation. A welded metal bellows seal is made through a process of stamping disc-like plates in specific contoured shapes and welding them in pairs at their inside diameter to form the individual convolutions of the bellows. which require heavy gauge liners. Flow liners are installed in the inlet bore of the expansion joint to protect the bellows from erosion damage due to an abrasive media or resonant vibration due to turbulent flow or velocities which exceed: Expansion joints that are installed within ten pipe diameters downstream of elbows, tees, valves or cyclonic devices should be considered to be subject to flow turbulence. stream In the majority of applications, total shutdowns are infrequent, therefore a bellows with a predicted cycle life of one or two thousand cycles is usually sufficient to provide reliable fatigue life for decades of normal service. As seen above, for finite length expansion joints, the lateral and bending stiffnesses are related by the equation: Because of this exact relation, and since the length is known, the user can only enter one of these two values. 111 0 obj<>stream is the dead weight or force in pounds required to Password. Available stock parts are presented in the Stock Bellows Data List. Facilities Already a Member? !9lX+lZJ$@n)20R]uU^X!&R{`mP>>To}A)C(@SD%%Rdbd) #rJ F.R*TeI(}#0g)$\,3>J4iIvRraECS!,UmJ^,9q We have received your request and will respond promptly. % Depending on application, the actual squirm pressure may be considered the maximum internal proof pressure (see Maximum Operating Pressure below). The squirm rating is provided for reference purposes and will vary with convolution wall thickness (within the tolerance range). X#d7-A.4\B&O-\rk&'WP8pj_9mWREM:X70 Cup Neck: C type necks provide an alternate attachment configuration and are typically selected to meet limited access requirements. 0000014363 00000 n 76 36 Note that it may be difficult to tell what kind of relief valve is installed from the external appearance of the relief valve. Webused to form the Bellows, -46 = Wall Thickness (.0046), -80 = Spring Rate (80 lbs/in.). For a "point" expansion joint, the length is unknown, so all three stiffnesses must be defined for the model, Modeling And Analysis Of The Piping System. Creating the future. PPPL EVMS Page In some cases this deformation is minor and will not affect the bellows function. a]tE!5GEN vGOH. Stock number nomenclature is composed of four elements separated by dashes (-). Tube OD(inches):0.125 X Where : F - The load (force) imposed on equipment on either side of the bellows. Some insulating materials, if wet, can leach chlorides or other substances that could damage a bellows. The Stock Bellows Data List presents available neck configurations for stock bellows. This causes excessive closing force, which in turn causes loss of the lubricating film between the sealing faces, excessive face heat and, eventually, seal failure. Most standard bellows seals are typically balanced to approximately a 70/30 ratio. It is inadvisable to use the total maximum deflection in compression when long life is required. `ouE! Y:t$"qM-:`I}`Tvm?e!|qZzbeT8fsxI\Z(oalY7dKJ29UD:Q%9v?]VOR>I=bfd'1zzfO ,V@kF?H0GiYz*xbrkXX(ywPa5>S;>NS_ _%0J'mIpBfsMu7R.0t*/mNy0/k{>;5'K.unVqB_cs8 [zzGg 0000011393 00000 n QO.N 0000125561 00000 n When multiple FSEs are present, the spring rate is given by !9lX+lZJ$@n)20R]uU^X!&R{`mP>>To}A)C(@SD%%Rdbd) #rJ F.R*TeI(}#0g)$\,3>J4iIvRraECS!,UmJ^,9q Home - EJMA Experimental verification of the axial and lateral - ScienceDirect Custom tolerances of 5 % or less can be achieved. Expansion joints consist of a flexible bellows element with end fittings such as flanges to allow connection to the adjacent piping or equipment. ?//H|GGiV/zwn ;Mt4Y`E)ei}: _&QJR|^x'c _ug5}DZd'k0=xY KfyW=W^+Ms0*;V2 lacO:r`ykP`Wg1[$9xE!1a$p{tq'y-;nr6 Is2%+ ,P^1pH+Y5h.Y5~JK?:#Hd'c WebExpansion Joint Spring Rates Axial Spring Rate (lbs./in.) *;T]W!B,,7Cf)eAadL:{7E0GXB Y]dRmVCYPZ{dBy'N3sTWnk,5 :$.g} The first element refers to the material; the second represents the outside diameter of the tubing used to form the bellows; the third identifies the wall thickness of the tube; and the fourth indicates the spring rate. mbi_XxJ?wum}ba]ZY _j|}q8u\>a&Tl_)BS(]H? 0000017266 00000 n These anchors are, as the name implies, intended to anchor the piping system in one direction, while allowing movement to occur from a transverse direction. 10 0 obj << /Length 11 0 R /Filter /FlateDecode >> stream 0000097781 00000 n Where the diagonal temperature difference line of 250C cuts the horizontal pipe length line at 100 m, drop a vertical line down. Figure 3: Weld bead integrity is ensured by preventing excessive root gap with bead geometry, bead thickness and roll-over control. f DEtn i C mbp f =17 3 3 . Stock tolerance is typically 0.015. Hydro-formed bellows function best in the compressed state. Installation misalignment reduces the total movement capacity of the expansion joint. WebCalculate Kn from the equation: Kn = 0.1906P1 - 1000 0.2292P1 - 1061 If P is 1423 psig or less, Kn = 1.0. Split convolution necks are also typically incorporated to customize the length or diameter of a stock bellows neck. endobj Join your peers on the Internet's largest technical engineering professional community.It's easy to join and it's free. If you look closer, you will see us. Split Convolution Neck*: S necks can be made on one or both ends of any bellows. External pressure does not cause squirm regardless of length. Ventura, CA 93003. (2) and (3). 0000001531 00000 n Web Hydro-formed bellows function best in the compressed state. ,|GAC0;^PCdB !=~nqAPa+OE=5}:60ed2AW=km>8|*(wb.}pE|Ne0#..8"!;0>i_ytA?pE{!x#4CI)):(|u(yq(vC~-tL"}@Do|G37CmE'+>OFS8S E#/w*t#ctGztt]ks H 3m4fdO(twa8qQo-d5|h"k"(1,J9Fd!@.ia4]ttmp/v mVA[iT6mA-MGvM6IGvk6]{mwH4O}u:CV}tVWxzk]__O%kojHuY6\:~hA~l{*~F7~'mu If P is more than 1423 psig, up to and including 3223 psig, Kn is calculated. 0000042780 00000 n This resistance is stated as spring rate and measured as the force required to deflect the bellows 1 in the axial or lateral direction; or inch-lbs./degree for angular rotation. hb```a``; B@1v,97L=1)Ym3t12i5_wv.sn3 vK]kEH&os%iSbIE3kC.,r0?0O#Gb+X?LpliTa?P.+IT-n69,}^F C'Z3rnTrzdlV>`uKi4c&DB " 0000006687 00000 n Face width: Narrow face width typically results in less heat generation at the seal faces. 0000043679 00000 n Squirm will not occur if the bellows is guided internally or externally by a rod stem or in a close fitting bore. Long Cycle LifeCycle lives in excess of those shownin tables 1, 2, 3, and 4 can be achieved with properuse and maintenance. Oterall bellows spring rate (Ibs/in.) Custom tolerances of 0.005 or less can be achieved when the spring rate is not critical. Acts as a spring to keep the primary sealing faces together, Transmits torque from the set screw collar in the seals rotating face, High strength with the ability to withstand high pressures, Precise design and performance characteristics, Low spring rate (the amount of force required to compress the bellows a given distance), Allow for optimal plate shape designnesting ripple, It is important that state-of-the-art manufacturing processes are used to create the bellows to ensure weld integrity by preventing excessive root gap with bead geometry, bead thickness and roll-over control (Figure 3). *Eng-Tips's functionality depends on members receiving e-mail. The welded metal bellows assembly (Figure 1) performs several functions: Welded bellows have specific advantages, including: Deciding that an edge-welded metal bellows seal is optimal for your application is not the end of the selection process. 0000004458 00000 n ?,mF| BwWdY3#l%lfu1oYo>I|OE)6Y3jrgf{k'g7w.;XwJyG?Z1tMub4p~$gYZ0T\kG B4;y98573: i mn-@W}'`x)R,,|zrs=!+AM_'Gpp o'Nz6g#=f;>:[?@_y2zq"ZzIbSLFzJJ5cJrVF*C-~;PAf-h}fhd (A) Mean Effective Area (square inches) HlU]j1|S|c:FP(}HJ3M!Y4aW}{?^pLlm0|:nZQ'|DdZjsQ:Af}H\zhz5N_YziY/\5X`HGh #J@& ]E -%>[ WebEach bellows is mass spectrometertested to 1 X 10-6 cubic centimeters per second ofhelium. 0000097962 00000 n Movement beyond the maximum deflection in compression or extension beyond the relaxed free length of convolutions will decrease cycle life, change the spring rate and cause permanent deformation which will not allow the bellows to return to its original length without the utilization of mechanical force. Repeated plastic deformation of the plates (beyond their plastic limit) during deflection can result in fatigue and greatly reduce seal life. Not all bellows in the industry are fitted with vibration dampeners, which help prevent any potential damage from harmonic vibration caused by episodes of dry-running. ;_O4QK=6O-|xn|@wP/n7N]PKw6`S19`t%[@;[-ga[l}Kfaf4/ )2 0` Z{SpWv7/Uoo@ OM)} 4!*;gJBE FwzTMM"Z"c|Q2>C9l6QrLHzr@=[DA endstream endobj 11 0 obj 867 endobj 19 0 obj << /Type /XObject /Subtype /Image /Name /im1 /Filter /CCITTFaxDecode /Width 396 /Height 160 /BitsPerComponent 1 /ColorSpace [ /Indexed /DeviceRGB 1 18 0 R ] /Length 20 0 R /DecodeParms << /K -1 /Columns 396 >> >> stream 0000003558 00000 n Different factors and product characteristics will impact overall seal effectiveness, and only with an understanding of these differences can plant operators select the most appropriate solution for the application. The bellows designer selects the thickness and convolutiongeometry to produce a bellows design that approaches, and often exceeds thecapacity of the adjoining pipe to contain system pressure at the specifieddesign temperature. Bellows 2 0 obj 0000025211 00000 n Pressure thrust force is directed into the immovable main anchor. The behavior of a bellows under load is described by the following equations: F = axial force in each convolution (also the axial force throughout the entire bellows), lb, f = axial stiffness per convolution, lb/in, Kax = total expansion joint axial stiffness, lb/in, ex = axial displacement per convolution, in, X = total axial displacement of joint, in, Mr = bending moment in each convolution (also the bending moment supported by the entire bellows), in-lb, D = is the effective diameter of the joint (equal to the inside diameter plus the height of one convolution), in, er = axial displacement per convolution resulting from a rotation of the convolution,in, r = bending rotation of single convolution, radians, V = shear force in each convolution (also the shear force supported by the entire bellows), lb. is the dead weight or force in pounds required to compress a bellows one inch. Bellows are manufactured from relatively thin-walled tubing to form acorrugated cylinder. 0000002282 00000 n The convolution pitch is approximately equal to the convolution free length divided by the number of convolutions (Column 13). \$!s1K{0|;^_lpvi8e [PFi-YUM`O{P8s~P ^X=}j>vqs@t Introduction to Pressure Relief Devices - Part 1 | Valve Magazine
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