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$@zk]Ky"\uQ>TMB Password. Corp. All Rights Reserved. 0000003890 00000 n If P is more than 1423 psig, up to and including 3223 psig, Kn is calculated. ):80. In most applications, design movements cause the individual convolutions to deflect beyond their elastic limits, producing fatigue due to plastic deformation, or yielding. When critical squirming pressure is reached, a slight bow, or sideways movement occurs. Each convolution is made up of a male and female plate that allow the seal to be designed with a short axial space. The maximum deflection in compression is defined as the maximum compressed movement (inches) from the convolution free length position (Column 7) that will not result in permanent deformation of the convolutions. Formulas: HWiTSgI 8SEGg#H!Y*e Y$%KGM.j@YlxLMpBRcR Dmtphso=]90BD r *P3@ d:p ~X4;9WNFVWo\k~W.P@ 't&2ijPZ*ZB\Gsf8W{xb 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. Custom tolerances of 0.0005 or less are possible. for Engineering Services is ready to help you across Canada, USA and Arabian Gulf Area. Now the expansion joint is forced to compress or extend axially, solely in response to dimensional changes in the pipe segment located between these main anchors. Note however that the bending flexibility coefficient should not be used in any piping program. 0000003945 00000 n Dashboard Catalog Packagespkg Latest Standardsls Advanced Searchas Browse Catalogics SIST Tube OD(inches):0.125 Bending and lateral convolution spring rates can be computed from the axial spring rate. Root Neck*: R necks can be made on one or both ends of any bellows. d~8*[]:w!zI1*0C Promoting, selling, recruiting, coursework and thesis posting is forbidden. 4 0 obj (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.). +7gusQwf46PZCwcUj:y *{QCAh|t},w2;3t\uw=a? (I) Convolution Inside Diameter (inches) Mini-Flex. External covers are mounted at one end of the expansion joint, providing a protective shield that spans the length of the bellows. startxref 0000004782 00000 n 7 Things to Know Before Selecting Welded Metal Bellows Custom tolerances of 0.001 or less are possible. 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. The wall thickness can be modified under certain conditions. In most cases, multiple convolutions are required to provide sufficient flexibility to accommodate theexpected expansion and contraction of the piping system. Thefollowing definitions are provided to assist in part selection and customization to meet engineering design requirements and objectives. This is especially important in the oil and gas and chemical industries, where pumping liquid from one area to another is complicated by great temperature extremes. !9lX+lZJ$@n)20R]uU^X!&R{`mP>>To}A)C(@SD%%Rdbd) #rJ F.R*TeI(}#0g)$\,3>J4iIvRraECS!,UmJ^,9q 721 Lateral Spring Rate (lbs./in.) ey = axial displacement per convolution resulting from a lateral deflection of the convolution. A series of convolutions is then stacked and welded at the outside diameters to form the bellows capsule. Bellows volume capacity (less the neck inside diameter) is effective area multiplied by the convolution free length (L): V=AL. *;T]W!B,,7Cf)eAadL:{7E0GXB Y]dRmVCYPZ{dBy'N3sTWnk,5 :$.g} Tie rods eliminate pressure thrust and the need for main anchors required in an unrestrained piping system. 112 66 HV6S 9ClSma$^/U`K]HJE!H|3oqtY4PyF9f~'XY6[p'xl.tpv {L` !>bq]Vx;+=g+bN>T"[|r6xufG>Q9 /-[x+#]%; 7 GHL #t%Jh'c~ /_TUX]q[UWCEnqo%ms!-2T . Squirm will not occur if the bellows is guided internally or externally by a rod stem or in a close fitting bore. The minimum internal or external burst pressure [pounds per square inch (PSI)] represents the minimum internal or external pressure that will not result in fracture when a bellows is restrained from squirm or sideways movement. Differentiating bellows features include plate shape and thickness, vibration attributes, double- or single-ply, face-angle, etc., all impact product effectiveness. is the dead weight or force in pounds required to 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. If misalignment can not be avoided, contact one of our engineers for guidance. Similarly, the spring rates of two-ply bellows proved to be significantly lower than those of single-ply bellows with twice the plate thickness. <>>> Join your peers on the Internet's largest technical engineering professional community.It's easy to join and it's free. ;_O4QK=6O-|xn|@wP/n7N]PKw6`S19`t%[@;[-ga[l}K5:{Dz|0jfF!"A 0000015479 00000 n Pressure-Relief Valve Bonnets To Plug 0000012394 00000 n Transverse motion which is perpendicular to the plane of the pipe with the expansion joint ends remaining parallel. This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. (A) Mean Effective Area (square inches) Tight tolerance control is achieved by applying uniform pressure on the outside diameter using a round collet while supporting the inside diameter with a standard plug gage. The definitions in this design guide are related to columns 1 through 13 of the Stock Bellows Data List. Bending and lateral convolution spring rates can be computed from the axial spring rate. Intermediate anchors can isolate multiple expansion joints that are installed in series to accommodate large motions beyond the capability of a single expansion joint. For bellows with straight flat segments, the variability of the micro-structure in the heat-affected zones results in less reliable weld joints. u:T+$MZ/r u JtzQTyARy8PDrYF4 &ou@lMV|!5O>oEf]j~ 6['N:hS7ML|Va)usf0vD;KfljV 0000001981 00000 n 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. Main anchors are intended to anchor the pipe from motion in any direction. 0000011000 00000 n 0000001593 00000 n See . Care must be taken to not over stress thin-walled necks. % Stock bellows are usually rated at 30% to 50% of the maximum deflection in compression. Reduction of the bellows length due to piping expansion. Mini-Flex Corporation | Metal Bellows Design Guide 0000097856 00000 n Before you specify a metal bellows seal, you need to determine the proper pressure rating required by your application in relation to temperature, speed and sealed fluid lubricity, as well as determine if the seal is capable of handling reverse pressure, especially in dual-pressurized seal arrangements. 0000110821 00000 n I am a little confused about the bellows expansion joint spring rate. WebThe spring rate of the axi symmetric FSE, K AS will be computed as force applied (F axial) / displacement induced (d). trailer 0000003558 00000 n 7,459 Angular Spring Rate (in.-lbs./deg.) Care must be taken to not over stress thin-walled necks. 0000002494 00000 n 4hv>;(!%`A{ud"ypwao>R8x6 The convolution pitch is approximately equal to the convolution free length divided by the number of convolutions (Column 13). A high spring rate is undesirable because of the significant changes in sealing face loading with only slight changes in seal operating length. &h w >AlSz/B>-S>r:QWPSdAt* `E}zh #g(rY Over 200 global locations. 0000009436 00000 n @iv];M[zn)8Cd}uv.OC*7TKEFW|4!Pw@dG!(~;"&F Z This is because the so-called bending flexibility is calculated by applying a moment (Mr) to the free end of an expansion joint and observing its end rotation (). The Stock Bellows Data List presents available neck configurations for stock bellows. WebEN 14917:2021 - This document specifies the requirements for design, manufacture and installation of metal bellows expansion joints with circular cross section for pressure applications with maximum allowable pressure greater than 0,5 bar.
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