The new edition of EJMA has some significant changes which are highlighted in this excerpt in addition to some useful relevant engineering dataFull description
The new edition of EJMA has some significant changes which are highlighted in this excerpt in addition to some useful relevant engineering dataFull description
There are some significant changes in the tenth edition of the EJMA standards
Descripción: norma de diseño de juntas de expansion
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operations mangement textbook
Descripción: Reference Data Best Practices Changes
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What changed in the EJMA 10th Edition?
EJMA-The Expansion Joint Manufacturers Association, Inc. The Expansion Expansion Joint Manufactur Manufacturers ers Association Association is an organization organization of of established manufactu manufacturers rers of metal bellows type expansion joints. EJMA was founded in 1!! to establish and maintain "uality design and manufacturing standards. These #tandards #tandards combine combine the $nowledge $nowledge and experience experience of of the association%s association%s Technical &ommittee &ommittee and are a'ailable to assist users( designers( and others in the selection and application of expansion joints for safe and reliable piping and 'essel installation. EJMA carries out extensi'e technical research and testing on many important aspects of expansion joint design design and manufacturing manufacturing.. EJMA 1)th Edition Edition is the most most current current edition and and supersedes supersedes all pre'ious publications. Triad *ellows Triad *ellows +esign and and Manufacturing Manufacturing uses uses bellows design design software software based on EJMA 1)th edition guidelines.
The Expansion Joint Manufacturers Association (EJMA, The Authorit! on Meta" Expansion Joints has re#ised the standards in the "atest 10 th Edition EJMA #tandards are recognized throughout the world as the authority on the proper selection and application of metallic bellows type expansion joints for safe and reliable piping and 'essel installation. The Tenth Tenth Edition Edition standards standards combine the the $nowledge $nowledge and experience experience of the leading leading manufactur manufacturers ers of expansion joints into an in'aluable reference document. Triad *ellows designs and manufactures metal standards . bellows and expansion joints to the latest EJMA 10th Edition standards. ,
What changed in the EJMA 10th Edition? 1.
The lim limits its fo forr ,ow ,ow 'el 'eloci ocitie ties s whi which ch ca can n be be toler tolerate ated d by by the the bel bellow lows s with without out th the e use use of a ,ow ,ow liner ha'e changed. -low energy and bellows ply interaction is now considered. As the number of plies in a multiply bellows increases so does the allowable ,ow 'elocity without an internal ,ow liner. /see table below0 . A new new app appro roach ach was de' de'elo eloped ped for the de desig sign n of re rein infor forced ced be bello llows ws(( resu resulti lting ng in a mo modi2 di2ed ed set of e"uations for some stress components and for the spring rates. The result was that the calculated bending stress due to de,ection could be considerably reduced. 3. The nu numbe mberr of of fati fatigue gue cy cycle cles s can can now be cal calcu culat lated ed fr from om the sa same me set set of of fati fatigu gue e cur' cur'es es whi which ch are rele'ant for the unreinforced bellows. The bellows fatigue life or cycle life calculations were greatly enhanced and simpli2ed. 4. The cal calcu culat lation ion of un uni'e i'ersa rsall type type Exp Expan ansio sion n Join Joints ts has bee been n simp simpli li2ed 2ed by a modi modi2ed 2ed e" e"uat uation ion for the axial mo'ement per con'olution. !. An acc accep epta tabl ble e radi radial al gap gap bet betwe ween en e"u e"ual aliz izin ing5 g5re rein info forc rcin ing g ring rings s and and the the root root of of con'olution5bellows tangent is introduced to section 6 6. The 1)t 1)th h Edi Editio tion n has has bee been n mod modi2e i2ed d to to inc includ lude e Eng Englis lish h 7 Met Metri ric c uni units ts of of meas measur ure. e. Thi This s incl includ udes es standard con'ersions in addition to constants used in calculations. 8. Tigh Ti ghtne tness ss of of bell bellows ows(( band bands( s( and and rin rings gs du due e to di dissi ssimil milar ar mate materia riall growt growth h rate rates s is con consid sider ered ed.. 9. *ell *e llow ows s pit pitch ch an and d hei heigh ghtt tole tolera ranc nces es wer were e red rede2 e2ne ned d rel relat ati' i'e e to di diam amet eter er.. . The Th e dis disti tinc ncti tion on of th thin in 'e 'ers rsus us th thic ic$ $ bel bello lows ws ha has s bee been n add added ed.. 1).. 1) *enchm *en chmar$ ar$ tab table le inp inputs uts and and outp outputs uts ha'e ha'e been been re re'i 'ised sed(( with with mater material ial clas class s and cor corre recti ction on factor. 11.. 11 #ing #i ngle le *el *ello lows ws Ax Axia iall :ib :ibra rati tion on &o &ons nsta tant nts s wer were e re' re'is ised ed.. 1.. 1 +e2n +e 2nit itio ions ns in in the the ;ome ;omenc ncla latu ture re se sect ctio ion n 1.3 1.3 ha' ha'e e been been cla clari ri2e 2ed. d. ;ote< this is not intended to be a comprehensi'e list of changes and is for reference only. EJMA 10th Edition $e#ised A""o%a&"e '"o% e"ocities Without a '"o% )iner
&alculation =esults +e2nitions *d+ The factor read from the EJMA -igure &6 /or A#ME :>>>0 for the listed cur'e number and x 'alue. >t is used in speci2c design calculations to relate ?shaped bellows con'olution segment beha'ior to a simple strip beam. *f+ The factor read from the EJMA -igure &! /or A#ME :>>>0 for the listed cur'e number and x 'alue. >t is used in speci2c design calculations to relate ?shaped bellows con'olution segment beha'ior to a simple strip beam. *p+ The factor read from the EJMA -igure &6 /or A#ME :>>>0 for the listed cur'e number and x 'alue. >t is used in speci2c design calculations to relate ?shaped bellows con'olution segment beha'ior to a simple strip beam. 1+ *ellows tangent circumferential membrane stress due to internal pressure. >n case of external pressure the reinforcing e@ect of a possible external collar is excluded. 1+ &ollar circumferential membrane stress due to internal pressure. >n case of external pressure the reinforcing e@ect of a possible external collar is excluded. + *ellows circumferential membrane stress due to pressure. + *ellows meridional membrane stress due to pressure. /+ *ellows meridional bending stress due to pressure. + *ellows meridional membrane stress due to de,ection. + *ellows meridional bending stress due to de,ection. $ated Max Axia"+ The maximum amount of mo'ement /axial extension( axial compression( lateral de,ection( angular rotation( or any combination thereof0 which an Expansion Joint is capable of absorbing. This rating may be di@erent for each size( type and ma$e of Expansion Joint and is established by the manufacturer. Tota" E2ui#a"ent Max Axia"+ *ellows are rated by the manufacturer in terms of maximum allowable axial displacement per con'olution( ec and ee. The design of e'ery Expansion Joint must be such that the total displacement per con'olution from all sources does not exceed the rated 'alues.
3e""o%s A""o%ed tress+ Allowable material stress at design temperature( unless otherwise speci2ed( from the applicable code. 3e""o%s E at Te4perature+ Modulus of Elasticity at design temperature( unless otherwise speci2ed( for material. 3e""o%s 5ie"d at Te4p+ ield strength at design temperature( unless otherwise determined( of bellows material after completion of bellows forming and any applicable heat treatment. Axia" Wor6ing pring $ate+ >n order to e'aluate the loads upon piping( supports( or e"uipment( it is necessary to determine the axial forces and moments re"uired to mo'e an Expansion Joint. The bellows resistance factor or wor$ing spring rate is shown in lbs per inch of compression or extension. )atera" Wor6ing pring $ate+ >n order to e'aluate the loads upon piping( supports( or e"uipment( it is necessary to determine the lateral forces and moments re"uired to mo'e an Expansion Joint. The bellows resistance factor or wor$ing spring rate is shown in lbs per inch of lateral o@set. 3ending Wor6ing pring $ate+ This is the displacement of the longitudinal axis of the Expansion Joint from its initial straight line position into a circular arc. Angular rotation is occasionally referred to as rotational mo'ement and is shown in B*# per degree. This is not torsional rotation. )i4iting *o"u4n Insta&i"it!+ &alculated maximum pressure in C#>D before expansion joint may s"uirm because of column instability. Excessi'e internal pressure may cause a bellows to become unstable and s"uirm. #"uirm is detrimental to bellows performance in that it can greatly reduce both fatigue life and pressure capacity. &olumn s"uirm is de2ned as a gross lateral shift of the centre section of the bellows. This condition is most associated with bellows which ha'e a relati'ely large lengthtodiameter ration and is similar to the buc$ling of a column under compressi'e load. )i4iting Inp"ane Insta&i"it!+ &alculated maximum pressure in C#>D before expansion joint may s"uirm because of inplane instability. >nplane s"uirm is de2ned as a shift or rotation of the plane of one or more con'olutions such that the plane of these con'olutions is no longer perpendicular to the axis of the bellows. >t is characterized by tilting or warping of one or more con'olutions. This condition is predominantly associated with high meridional bending stress at the root and crest of the con'olutions. A""o%ed *!c"es+ The fatigue life expectancy can be de2ned as the total number of complete cycles which can be expected from the expansion joint. A cycle is de2ned as one complete mo'ement from the initial position in the piping system to the operating position and bac$ to the initial position. &ycle Bife is theoretical and is dependent upon the maximum stress range to which the bellows is subjected. The fatigue life expectancy of an expansion joint is a@ected by 'arious factors such as< operating pressure( operating temperature( the material from which the bellows is made( the mo'ement per con'olution( the thic$ness of the bellows( the con'olution pitch( the depth and shape of the con'olution. Any change in these factors will result in a change in the life of the Expansion Joint. The wor$ hardening of austenitic stainless steel( induced during the forming of con'olutions( generally impro'es the fatigue life of an Expansion Joint often to a mar$ed degree. *on#o"ution 7epth %+ &on'olution height less the bellows material thic$ness. 3e""o%s )ength )e+ nec$s.
*ellows con'oluted length /Bb0 plus the length of the bellows tangent ends or
3e""o%s )ength )&+
*ellows con'oluted length or li'e length.
3e""o%s )ength )u+ +istance between outermost ends of the con'olutions in a uni'ersal expansion joint. ero length is shown for single bellows. Tota" )ength+ Total length of the expansion joint including the possible pipe ends. >t is calculated as either Bb or Bu plus length of pipe ends.
Thic6ness tp+ *ellows material thic$ness for one ply( corrected for thinning during the forming of the bellows con'olutions. E8ecti#e Area Ae+ Axial force or pressure thrust is caused by the internal pressure of the bellows. This is calculated on the full e@ecti'e cross section of the bellows $nown as the e@ecti'e area. Cressure thrust can be calculated by multiplying the wor$ing pressure by the e@ecti'e area /C#>D x Ae0. 'actor 9u+ -actor establishing relationship between the e"ui'alent axial displacement per con'olution due to lateral de,ection. Thrust 'orce+ Axial force or thrust caused by the internal pressurization of the bellows. The thrust force is calculated by multiplying the wor$ing pressure by the e@ecti'e area /C#>D x Ae0.
A""o!s :sed in 3e""o%s and )ight Accessories 'or4ing ATM A/0 T-1
ATM A/0 T0/;0/)
ATM A/0 T1;1)
ATM A/0 T-10
ATM 3- A))<5 0
ATM 3-1= A))<5 00 >nconel 6))
ATM 3-// A))<5 >nconel 6!
ATM 3-/ A))<5 > Fastelloy I
ATM 3- A))<5 *- Fastelloy &86
Feat resistant alloy for bellows limited to 1))G Titanium stabilized grade of 3)) series stainless steel Hptimum resistance to intergranular corrosion and stress corrosion crac$ing =elati'ely good heat resistant alloy rated to 1)))GH@ered in dual certi2cation ?sed particularly for accessories on expansion joints Applied to temperatures up to 1)))GH@ered in dual certi2cation Cro'ides excellent corrosion resistance Alloy stabilized with molybdenum Temperature range up to 1!))GAustenitic heat resistance alloy Excellent resistance to oxidation Bimited a'ailability in bellows material thic$ness =ecommended up to 1!))GFigh nic$el alloy &ombination of strength and resistance to carburization =esistant to oxidation and thermal shoc$ Hperates at ele'ated temperatures up to 1))GFigh nic$el alloy with great carburization and oxidation resistance =esistant to chlorides( dry and gaseous at ele'ated temperatures ;ot recommended for use in extreme heat where sulfur is present Temperature resistant up to 1))GFigh nic$el alloy with outstanding strength A"ueous corrosion resistance due to content of molybdenum and columbium =ecommended for temperatures up to 1!))GFigh nic$el alloy grade with excellent strength Hxidation resistant
Temperature limited to 1))GFigh nic$el molybdenum and chromium alloy with traces of tungsten Excellent resistance to pitting and stress corrosion crac$ing ?sed for heat exchangers( ducting and marine applications
A""o!s :sed for @ard%are %ith Expansion Joint Manufacturing ATM A-
&arbon based steel plate used for plate ,anges( tie rod ears( and gussets in temperatures up to 8!)G-
ATM A-1 $.0
#tronger alloy steel plate with better properties than A36 plate ,anges and hardware up to 1)))G-
ATM A-/0 T3)4( T316( T31
#tainless steel plate used for special plate ,anges( gimbal
ATM A--E $.3
&arbon based steel pipe( welded and spot radiograph chec$ed on the
hardware( etc. up to 1)))G-
seam weld rated to 8!)G-
ATM A10 $.3
Figher grade carbon steel pipe( seamless pro'ides weld eciency of 1))K radiographed seam rated to 8!)G-
ATM A-10
-orged steel =-#H ,anges( couplings( temperature and pressure rating 'aries
ATM A-/ $ WB3
ATM A1= ' $A7E
Cipe elbows( concentric reducers( and other nonforged carbon steel 2ttings
*asic stainless steel forging( co'ers =-#H ,anges couplings( temperature and pressure rating 'aries
3)453)4B( 3165316B
ATM A-1 $A7E
&o'ers stainless steel pipes and pipe based products with temperatures up to 1)))G-
3)453)4B( 3165316B
ATM A-1C $ 3
Alloy steel threaded rod and bolts used in conjunction with restrained expansion joints
ATM A-1C/ $ @
Alloy steel hea'y duty hex nut paired with A#TM A13 D= *8 threaded rod and bolts
ATM A-1C $ 3=
&erti2ed stainless steel threaded rod used in conjunction with restrained expansion joints
ATM A-1C/ $ =
&erti2ed stainless steel hex nuts paired with A#TM A13 D= *9 threaded rod and bolts
