Welcome to Presentation on PI PE SUPPORT SYST SYSTEMS EMS & PI PI NG FLEXI FLEXI BI LIT LITY Y (03-Feb-2005)
Program Objectives 1.
To cr crea eate te a se sens nsee of ap appr prec ecia iati tion on fo forr co comp mpli lian ance ce of be best st engineering practices , and improve understanding of piping through preliminary knowledge of Pipe supports.
2
To enable faster & better interpretation of engineering deliverables by working knowledge of these Pipe supports .
3
To enable maintenance engineers to take preventive action case of exceptions.
in
INDEX
PART-I
Overview.
PART-II
Support Basics.
PART-III Support Classification. PART-IV Support Detailing. PART-V
Support Design.
PART-VI Line Designation PART-VII Piping Flexibility PART-VIII Sample Drawings .
OVERVIEW
THE CODE ASME B 31.3 SPECIFIES UNDER CLAUSE 321.1.1, THE OBJECTIVE OF THE SUPPORT DESIGN AS PREVENTION OF
Piping stress in excess of those permitted in the code. Leakage at joints due to misaligned flanges. Excessive thrust and moments on connected equipment (such as pumps and turbines). Excessive stresses in the supporting (or restraining) elements.
.
Resonance Resona nce with imp impose osed d fluid fluid indu induced ced vibr vibrati ations ons Excess Exc essive ive interfe interferenc rence e with therma thermall expansio expansion n and contra contractio ction n in a piping system, which is otherwise adequately flexible.(No unwanted rigidity). Unintentional disengagement of piping from its supports. Excessive piping sag in systems requiring drainage slope.
PI P E SUPP ORT ORTS S STANDAR STANDAR DS
1. 2. 3. 4. 5. 6.
A NS NSII31.1 & 31.3 ie Po w e r Pip ing & Pro c e ss Pip ing *MS *M SS –SP 58 Pip e Ha ng e rs a nd Sup p o rt : Ma te ria ls, De Des sig n & Manufacturers *MSS *MS S –SP 69 Pip e Ha ng e rs a nd Sup p o rt : Se le c ti tio o n & Ap p lic a ti tio o n. *MSS *MS S –SP 77 G ui uid d e line s fo forr Pip e Sup p o rt C o ntr ntra a c tua l Relationships. *MS *M SS –SP 89 Pi Pip e Ha ng e rs a nd Sup p o rts ts:: Fa Fa b ric a ti tio on & In st a lla t io n Pr Pra c t ise s. M SS –SP 90 G ui uid d e line s o n Te Te rm ino lo g y of o f Pi Pip e Ha ng e rs & Supports. * Thes These e a re a d vis visory ory stand stand a rd s rec om m end in ing g stand a rd p ra c ti tic c es .
SUPPORT OR SUPPORTING ELEMENTS The term The term “su “supp pport orts” s” or “su “supp pport orting ing ele eleme ment nts” s” en enco comp mpass asses es the the entire range of various methods of carrying the weight of pipeline and the conte contents. nts. It theref therefore ore includes includes “hangers” “hangers” which generally generally carry the weight from above, with the supporting members being mainly mai nly in ten tension sion.. Like Likewise wise,, it incl include udess “su “suppo pports rts”” whic which h on occasion are delineated as those those which carry weight from below, with supporting member being in compression. Pipe supports refer to the physical structural elements such as prepr e- en engi gine neer ered ed st stru ruct ctur ural al ste steel el alo along ng wit with h suit suitab able le spr sprin ings gs,, snubbers, fixed on pipes to reduce or nullify the forces created in piping systems due to self weight, thermal expansion or contraction, shock load, etc.
Basic Term T erm inology
•
•
convey fluid/fluid pressure Pipe : Pressure tight cylinder to convey Pipe Support Elements: Transmit the load from pipe to structures& /or
pressure equipment Ex. Spring Hangers, Guides, Hangers. These are called Fixtures. Attachment like clips, clamps, strips etc. etc. are called Structural Structural Attachments. •
Piping Components: Joining/Assembling Mechanical elements for pressure
tight piping etc. like l ike Flanges, Gaskets, Valves, Expansion Joints, Hoses, Traps Strainers etc. •
Piping: Assemblies of piping components used to convey, distribute, mix etc.
flows. Also includes piping elements. •
Piping Elements: Any material or work required to plan & install piping system
is called piping elements. Specs, Materials, components, supports inspection etc. •
Piping System : Interconnected piping subjected to same set or varying sets of
Design conditions.
Continued….. Hot loa loa d / Hot setti setting ng / Op er era a ti ting ng loa d The w e ig ht tha t ha t the th e sp ring ha s to sup p o rt w hi hille the p ip e line sys ystt e m is in o p e ra t io n. Th is is a ls lso o c a lllle e d Operating load. Cold loa d / Cold sett settiing / Ins nstta lled loa d The w e ig ht tha t ha t the th e sp ring ha s to sup p o rt w hi hille the p ip e line sys ystt e m is NO NOT T in o p e ra t io n . Th Th is is a ls lso o c a lle d pre-set load. Tra rav v e l sto stop ps Limit the spring travel at the top and bottom to a small percentage beyond the specified range. In addition, they prevent the spring form moving while the spring is not in o p e ra ti tio o n (in (in p re -se t m o d e ) or in hyd ro sta ti tic c te sti ting ng p ha se. Tra rav ve l Co m p res ess sion o r ex exp p a ns nsiio n o f sp sp ring in “ m m ” fr from om Ho t to Co ld o r vic vi c e ve verrsa lo a d va ria ti tio o n.
Ele lem m e nts O f Pip Pip e Sup p o rt
1.
Fix tu re s: s: a . Ha ng e r Ro d s b . Sp ring ha ng e rs c . Tu rn Bu Bu c kl kle es d . Cha ins e. Anc hor hors s f. Brackets g . Gui Guid d es h. Sa d d le s
2.
Stru c tu ral Att Attac h ment ments s: a . Cl Cliip s b . Lug s c . U-b o lts d . Stra trap ps
Classification Class ification of Pipe Support s 1. 2. 3. 4.
Rigid or Weight Supports (Rod Hangers, Sliding supports, VS & CS Supports) Rigid Restraints & Anchors (Supplementary Steel or Structural Members ) Snubbers (Hydraulic & Mechanical ) Sway Braces
Rig igid id Ty p e Sup p o rts (W (We e ig ight ht sup sup p o rts ts))
All sliding type supports: supports: Ba re , Cl Cla a m p e d , Sho e , Dum m y sup p o rts ts,, b ra c ke t sup sup p o rts ts,, e tc . (s (sup up p o rte d fr fro o m b o tto m ). In thi this s the sup p o rts m e m b e rs a re in c o m p re ssio n.
Hangers rods (without spring): spring) : Will be supported from top. (Designed on the basis of max. weight carrying conditions, inc lud ing Hyd ro te st). In thi t his s the sup p o rts a re in te t e ns nsiio n.
SHOE
SADLE
CLAM P SHOE
B ASE SUP P T
B A S E A D J .S P T
B A S E EL L S P T
B ASE ADJ SP T
DUM M Y SP T
DU M M Y SP T SH OE
V ER T D U M M Y
A DJ . ELL. SP T
A D J . S P T.
A D J .G U I D E
ADJ. GUI DE
S P T. N O W E L D
TR U N N I O N
E L L .S P T .
SU P P OR T
S U P P OR T
C L A M P E L L .S P T
ROD HAN GE GER R
THE
ROD
DIFFERENNT
HANGERS
ARE
ATTACHMENTS
USED LIKE
FOR
NON
CRITICAL
SUPPORTS.
EYE-NUTS,TURNBUCKLES,RODS
HEX
NUTS & BOLT CLAMPS AR E USED USE D I N CONJUNCT CONJUNCTION ION WI TH HAN GER RODS. TURN BUCK LES ARE FOR FOR ADJU ST STM M ENT IN THE SUSPENDED LENGTH FROM THE PI PE.
ROD HANGERS
Offset Limitation of rod hangers a) b)
Pipe With Movement In Axial Direction Cold Pipe Positioning
– 1) Of Offse fset, t,Co Cold ld -- 2) Oper Operati ating ng Posit Position ion Hot Hot Permissible horizontal movement not to exceed +4° for Rod hangers .
A nc ho rs & Guid Gu ide e s (R (Re e str tra a int Ty Ty p e ) Anchors & Guides are provided to restrict movement of pipe in a ny one o r a ll 6 free free d o m o f mo vem ents ents.. 1. The hey y a re p ro vi vid d e d to re str tra a in, d ire c t o r a b so rb p ip ing movements. 2. The ir d e sig n ta ke s into a c c o unt forc forc e s/ m o m e nts a t the se elements caused by internal pressure and thermal expansion/contraction.
Sup p lem e nta ntarry Stee l To a tta c h the p ip e w ith va rio us typ e o f sup sup p o rts mentioned above we need to tie it with the existing str truc uc tur ture e . To a c hi hie e ve this w e e ith the e r w e ld str truc uc tura turall members to the supporting elements or supporting b ra c ke ts o n to th the e e xisti ting ng str truc uc tur ture e.
PIPE SUPPORT MATERIAL FOR COLD SERVICES 1 . N at a t u ra r a l s e a s o n ed e d w o o d – I S 3 62 6 2 9 G r .I •
Along the grain cutting & acros acrosss the grain loading
•
Tim ber group A
1 . H DP D P UF U F – C o m pr p r e s s i v e S t r e n gt g t h 7 00 0 0 00 0 0 K pa pa OR 7 0 K G per cm 2 •
L o y de d e gr g r a d e 32 3 2 0 – 8 20 2 0 00 0 0 K P a - S ta t a n da da r d
•
L o y d e g r a d e 2 50 5 0 – 4 90 90 0 0 K P a - S t a n d ar d
•
L o y de d e g r a d e 3 00 0 0 – 7 00 0 0 00 0 0 K P a – ( I P CL C L C u st s t om o m iz i z ed ed )
Varria Va iab b le & Cons Co nsta tant nt Sup Sup p o rts (F (Flexib lexib le Sup p o rts ts))
Varriab le Sp rin Va ing g Sup p ort orts s: Variable spring supports are so called because they provide variable supporting forces as the pipe moves vertically due to contraction or e lo ng a ti tio o n. M a xim um va ria ti tio o n in in lo lo a d is 25%. Cons Co nsta tant nt Sp ring Sup p o rts ts:: Constant spring supports are used where thermal movements are too la rg e (o (ove ve r 2 inc inc he s & m a x 6% lo a d va ria ti tio o n is is a llo w e d ). Suc h sp sp ring supports are used to restrict the loads created in piping systems on to c riti tic c a l e q ui uip p m e nt no zzle s. NO TE: (In (I n Sp Sp ring Sup Supp p ort orts s sp rin ing g s a re not de sig ned for Hyd rotes otestt loa d s, howe ver sup p ort orts s m e m b ers a re d es esigne igne d to tak e hy d ro- tes testt lo lo a d s.)
Spring Han ger in four different dif ferent load condition c ondition s
a) Unloaded Position
b) Loaded in Hot position
c) Pipe moves down from cold to hot position
d) Pipe moves up from cold to hot position
TYP E S OF VARI ABLE –SPRI NG HAN GE GERS RS
Va ria iab b le Sp Sp ring Sup p o rts (F (Flex lexib ible le Sup Sup p o rts ts))
SELECTION OF FLEXIBLE SUPPORTS CONSTANT
SPRING
:
Constant spring hangers are selected where absolutely necessary, when the percentage variation of load from cold to hot should be less than ± 6% for critical pipelines, which give the lowest %, load variation. The geometry & kinematics of these constant spring hangers is such that theoretically and constant supporting force can be achieved throughout its full range of expansion and contract.
Constant Effort Eff ort Spring support
CONSTANT-SPRING SUPPORT
Co ns nsta tant nt Sp Sp ring Sup p o rts (F (Flex lexib ible le Sup p o rts ts))
VARIABLE SPRING Variable spring hangers are recommended for general use on non-critical piping systems & where constant supports are not required. The inherent characteristic of a variable spring is such that its supportings force varies with spring deflection and spring scale. The vertical expansion of piping causes a corrresponding compression or extension of spring & causes a change in the actual supporting force is equal to the product of amount of vertical expansion & the spring scale.
Comparison of variable support & constant support Springs
P ar ti cu l ar
Variable Spring Support
Con stan t Spring Support
Design
Sim p le design w it h H elical spring
Sophisti cated design w ith Sophisticated Spring & B ell Crank Cra nk Lever
A pp p p li l i ca c a ti t i on on
N on o n c ri r i ti t i c al a l a pp p p li l i c at a t io i o ns ns – Ex . Heat Exchan gers, Vessel, ordinary piping etc.
Cri tical Critic al appli ap plicat cations ions – E x. Steam pipin g near steam turbines , Steam Headers ,Boilers etc.
M ov o v e m en en t
A p p l i c a b l e f o r L o w t he h e r m al al movements (upto 50 mm )
Applicable for large th ermal movements (above 50 mm )
Space
Less sp ace for in st allat ion
Large space for installation
Cost
Low co st
High cost
Fo rm ulas And Ca lc ul ula a ti tions ons
Upward movement
- If Co ld lo a d is g re a te r tha n Ho Ho t lo lo a d
Do w n w a rd m o v e m e n t
- If Ho Ho t lo lo a d is g re a te r tha n C o ld lo a d
M o ve m e nt = (Col (Cold d loa d - Hot loa loa d ) / Sp ring ra te. If re re sult > 0 the then n m o ve m e nt d ir ire e c ti tio o n is up . Otherwise Otherwise , it's it's d o wn. Variability (% loa d c hange )
= ((Mo ve m e nt x Sp ring ra te ) / Ho t lo lo a d ) x 100
SNUBBERS Rigid restraints are usually necessary when the pipe is strong to survive loads such as earthquake or high winds or other dynamic loads such as fluid hammer. But when these restraints are used in high temperature piping at some location it may develop elevated stress levels. In these cases snub sn ubbe bers rs ar are e us used ed..
SNUBBER ASSEMBLY
Mechanical Snubber
a) Photograph b) Schematic
Hydraulic Snubber
a) Schematic b) Photograph
SWAY BRACES Sway braces are used to limit the effect of pipe vibration. These are little more than variable springs acting in horizontal plane. When sway brace is installed, the spring preload is adjusted to be zero when pipe is in the operating position. positio n. Sway bra braces ces,, like vari variabl able e spr springs ings,, do add som some e expansion stresses in the pipe.
SWAY BRACES
A) Vibration Control & Sway Brace.
B) Cutaway Section
C) Deflection of Spring when Thrust Exceeds Pre-compression
D) Tension Causes deflection of Spring in Opposite Direction
LOAD CO COM M BI NAT NATII ONS
Pipe supports must be designed to withstand any combination of loading which is postulated to occur simultaneously. Normal operating loads are either deadweight or deadweight plus thermal. These loads may be combined with occasional loads, as required by the design criteria of the specific project. Under certain conditions, capacities of materials may be increased for occasional loads. E.g. is the concept of service level instituted by ASME Boiler & Pressure Vessel Code, Section III. A typical spec for design load combination is as follows:-
Load Cases Normal
I Deadweight II Deadweight + Thermal
Upset
I Normal + relief valve discharge II Normal + earthquake(DBE) +relief valve discharge. III Normal + water hammer
Emergency
Normal + earthquake (DBE)+ Relief valve discharge.
Faulted
Normal + earthquake (DBE) + pipe rupture.
These loads These loads may be added added eithe eitherr algebrai algebraicall cally y to to arrive arrive at reali realistic stic value valuess or absolutely for added conservatism, according to the design criteria requirements.
M A XIM UM SPA N BE BET TWE WEE EN TWO SUP UPP PO RTS A s p e r AS A SM E B31.1 Ta b le 12.5 ad a d o p te ted d fr fro o m M SS- SP- 69
Pip e ( NB NB))
Sug g e sted Ma xim ximum um Sp a n Wat ater er mt mtrr. ( ft)
Airr / Steam mtr Ai mt r. ( ft)
1
2.1 ( 7)
2.7 ( 9)
2
3.0 ( 10)
4 .0 ( 1 3 )
3
3.7 ( 12)
4 .6 ( 1 5 )
4
4.3 ( 14)
5 .2 ( 1 7 )
6
5.2 ( 17)
6 .4 ( 2 1 )
8
5.8 ( 19)
7 .3 ( 2 4 )
12
7.0 ( 23)
9 .1 ( 3 0 )
16
8.2 ( 27)
10.7 ( 35)
20
9.1 ( 30)
11.9 ( 39)
GUIDELINES FOR LOCATION OF SUPPORTS
Support should be located at near as possible to concentrated loads as valves, flanges etc. To keep the bending stress to the minimum. When changes of direction in a horizontal plane occur, it is suggested that the spacing be limited to 75% of the tabulated values to promote stability and reduce eccentric loadings.
The standard span does not apply to vertical run pipes (risers) since no moment and no stress will develop due to gravity load in the riser. The support should be located on the upper half of a riser to prevent instability in overturning of pipe under its own weight. Support location should be selected near the existing building steel to minimize the use of supplementary steel.
SPECS FOR ORDER o
o o o
o o o
o o
The exact hot or operating load required to be supported during the working condition. Hydrostatic test load. The total travel. The direction of travel either upwards or downwards from the erected position. The set pin locking position (top, middle, bottom or as required). The basic model. Requirement of bottom accessory components such as rods, clamps etc. Any hazardous environmental conditions. Any special special finish on the the body body such as galvanizing etc.
Ph enomenon in Piping Flex Fle x ibility C RE REE EP RUPT RUPTURE URE STRENG HT Tim e d e p e nd a nt str stre e ss is us usua ua lly re re la te d to the “ C re e p Rup ture Str Stre e ng th” at high temperature. At temperature above 1/3 of the melting point most metals will exhibit creep in standard tensile test. If the load is kept constant the specimen will continue to deform and subsequently fail. Hence considering this creep, the allowable stresses are 62.5% of the yie ld st re res ss. Hence taking a conservative estimate the limit of the b e nd ing str tre e ss a t w hi hic c h p la sti tic c fl flo o w sta rts is 1.6 tim tim e s th the e a llo w a b le c o ld o r ho t st re res ss. FATIGUE ON PIPING
ARC Markl investigated the phenomenon of fatigue in piping. He observed that the fatigue failure occurred not in the middle of his test sp a ns ns,, b ut in in the th e vi vic c ini nity ty o f fitt fittiing s a nd tha t a lso a t a lo w e r str tre e ss th tha a n tha th a t forr p ip e s. Thi fo his s le a d to a fa c to r c a lle d “ Str tre e ss Inte ns nsiifi fic c a ti tio o n Fa Fa c to r” .
P iping Support Design Tips 1.
2.
3.
4.
5.
Since most piping systems are not made strictly of straight horizontal runs, the standard support spacing may not be applied uniformly throughout. Locations of supports should consider the following guidelines. Pipe supports should be located as near as possible to concentrated weights such as valves, flanges, etc. etc. From a pipe stress point of view, the best location location for support attachment is directly on the equipment. When changes of direction in a horizontal plane occur between the pipe and associated supports, such as with pipe elbows, it is suggested that the spacing be limited to three-fourths of the standard span shown in table. The standard span does not apply to vertical runs of pipe (risers) since no moment (and therefore no stress, as defined by the piping codes) will develop owing to gravity loads in riser. Support locations should be selected near existing building steel to maximize ease of design & construction and to minimize the supplemental structural materials used to transmit the pipe loading back to the building structure.
Key Maintenance Tips •
Adequa Adeq uattel ely y des esig igne ned d pip ipin ing g an and d su sup ppo port rt sy syst stem emss ar are e absolutely critical & important.
•
Majjor fa Ma fail ilur ure e of of su support rtss ca can be be ca catas asttro rop phic ic..
•
It be becom ome es abso absolu luttely ne neces essa sary ry for for mai maint nte ena nanc nce e eng engin ine eers to be very vigilant towards critical support systems and check for following common piping support problems : Shoe not res resti ting ng o n the th e sl slee p er ers s. Sh o e t w is ist e d . Su p p o rt rt w e a th t h e re re d a w a y. y. Trun unni nion on / Dummy bent on ver verti tic c a l lines nes.. Str tructur uctura a l me mb er ers s b ent nea nea r loo p s. LPDs em b ed d ed in soi soill thu thus s tur turni ning ng it it into into a n a nc hor support.
1. 2. 3. 4. 5. 6.
Key Maintenance Tips Continued…. • • • • • • • • •
Wo od o d e n b lo lo c ks ks p la la c e d un u n d e r e lb lb o w d um u m m ie ie s we a ther thered ed off off.. Guid Gui d e p la tes in guid guid ed supp or orts ts mi mis ssing. Pip e stops stops in axi axia l res estr tra a int b rok oken en / b ent ent.. Bloc ks attac h ed to thes t hese e pipe pipe stops stops wea th ther ered ed o f f . V ar ariiab le Spr Spriin g Su pp or orts ts Cor Corrrod ed. V a ria b le Sp Sp ring Supp Supp or orts ts loc ks not remo ved. Due to t o d isp la c ement Va Va ria b le sp sp ring su su p p or orts ts not operational. Pip e is is c or orrrod ed wher where e it it is is d irec tl tly y res esti ting ng o n sl slee p er rod. Line is is not supp or orted ted a d eq u a tel tely y , hi high gh c a nt ntiilever ever..
PIPING CLASS CODING
3 -C -C h a r a c t e r S y s t e m
: X - X - X X XX XX - X X X - X X
1 s t Slot Slot// Char Charact acter er : Line size in inches 2 N D Slo Slot/ t/ Cha Charact racter er : P-Process ; CWS-Cooling Water Supply ;CWR-CW Return; N2-Nitrogen; H2-Hydrogen; AS-Service Air; AI-Instrument Air; AP-Plant Air; FW-Fire Water; DMW-DM Water, etc. 3 r d Slot/ Cha Charac racter ter : 4 Digit Line Sr.No. 4 t h Slot/ Cha Charac racter ter : Piping Class a) First Character specifying : A-150# B-300# D-600 # E-900 # F-1500 # G-2500 # b) Middle No. specifying variants. (1 2 3 4 5 7 8 9 10 13 19 20) c) Third Character specifying : A-CS, B-CS MOLY, C D E H K M N S-PVC, T YMSRL Z-HDPE (Ex: A1A, A2A A3A, A4A, A4A, B1A, B2A.., B2A.., B1K, B2K, D1A,D2A, D5A, F2A, F2D, G2E)
5 t h Slot/ Cha Charac racter ter : Insulation Type IH, IC, IS, ET
Piping Flexibility An Introduction
Expansion Loads Piping system which is too well restrained will not be able to expand and large forces will develop at the points of lockup, causing large stresses to develop in the pipe. The ideal restraint conditions for thermal considerations is a total lack of restraint. Since this is not feasible, given other loads, some forces due to expansion will develop on restraints even in the most optimally supported system. Hence it is necessary to determine piping thermal movements for use in spring hanger selection and design of clearances in restraints.
THERMAL EXPANSION OF PIPING SYSTEM
(a)) Lo (a Loop op wit witho hout ut dir direc ecte ted d ther therma mall grow growth th (b)) Lo (b Loop op wit with h dire direct cted ed the therm rmal al mov movem emen entt
a.Poor Service/Piping Distortion.
b.Proper Service/Piping alignment & limited stresses through PSA .
c.Poor Service/ Unnecessary looping etc .
a.Good but Costly due to heavy design .
Ca lc ula ulati tio o n o f Pipe Pipe Exp a ns nsion ion A pipe will will exp and when hea hea ted up a nd c ont ontrrac t when co ol oled ed . This c a n be b e e xp re sse d thr thro o ug h the exp e xp a ns nsion ion form form ula ula..
The te m p e ra tur ture e e xp a ns nsiio n of p ip e s d e p e nd s o n the sta sta rt a nd fi fina na l temperature and the thermal coefficient of expansion of the piping m a te ria l. The g e ne ra l e xp a ns nsiio n fo rm ul ula a c a n b e e xp re sse d a s: dl =
x Lo x d t
where: d l = ex e xp a ns nsiio n (inc (inc he s) Lo = le ng th o f p ip e (inc (inc h) dt = temper temperatu aturre d if f er erence ence (o F) ∝
= linear expansion coefficient (inch/inch o F) (available in 31.1,
31.3,etc) Example: The rm a l e xp a ns nsiio n for fo r 1 m e te r C a rb o n ste ste e l p ip e a t 10 100ºC . d l = 6. 6.38 38// 10 Fo r C a rb o n Ste Ste e l
x 1000 x (2 (21 12 – 93) = 0. 0.76 m m / m eter
= liline nea a r e xp a ns nsiio n c o e ffi ffic c ie nt (inc (inc h/ inc ho F) = 6.38/ 10
Rem em b er Exp a ns nsion ion in SS SS p ipe will will be a p p ro x. 30 30- 50% m o re tha n in a c a rb on s stee teell pip pipe e
CTE OF PIPING MATERIALS (Total linear Thermal Expansion in / 100’) -300 °F
c A 10 6 (CS) A 31 31 2 – 3 0 4 (SS)
- 2 .2 4 - 3 .6 3
- 1 0 0 °F - 1 .1 5 - 1 .7 5
- 2 5 °F - 0 .3 2
7 0 °F (ambient) 0
- 0 .4 6
CTE (At 1000F) CS
6.13
micro in./In./ °F
SS
9.16
micro in./In./ °F
2 0 0 °F 0 .9 9
0
1 .4 6
4 0 0 °F 2 .7 0 3 .8 0
PIPE UNDER STRESS
The re a re tw o typ e s o f lo lo a d s w hi hic c h p ut a p ip e und e r str tre e ss: 1.
Prim a ry ry Lo Lo a ds d s: The se lo a d s a re typ ic a l lo a d s suc h a s inte rna l p re ssur ure e , exter exte rna l p re ssur ure e , gr g ra vi vita ta ti tio o na l fo rc e s like the w e ig ht o f p ip e a nd fl flui uid d . The se lo a d s a re g e ne nerra lly c a lle d a s sus usta tained ined loa d s. Fa ilur ure e o f the p ip e d ue to a n y of the me nti ntione one d loa d s a re c a lled a s c a ta str tro o p hi hic c fa ilur ure e s.
2.
Se c on o n d a ry ry Lo ad a d s: s: Jus ustt a s p rim a ry lo lo a d s ha ve o rig in in in so so m e fo rc e , sec o nd a ry lo lo a d s a re c a us used ed b y displacement o f so so m e kind . e .g the p ip e m a y b e und er lo a d if the ta nk noz nozz zle m o ves up o r d o w n. A p ip e sub sub jec ted to a c yc le o f ho ho t a nd c o ld fl flui uid d sim ila rly und und e rg o es c yc lic loa d s a nd d efor eform m a ti tion. on.
PSA OBJECTIVE Pip e St re ss a na lys ysiis is c a rrie d o ut to e ns nsure ure sa sa fe ty a g a ins nstt fa f a ilure o f the t he PIPING SYSTEM b y ve v e rifying t h e st ruc t ura l in in t e g rit y a g a ins nstt t he lo a d ing c o nd iti tio o ns ns,, b o th e xte rna l a nd inte rna l d ur uriing the life tim tim e o f the sys yste te m in the p la nt. Henc e the o b jec ti tives ves c a n b e sta ted a s : 1. Ens nsur ure e tha th a t the str stre e sse s in the p ip ing c o m p o ne nents nts in the sys syste te m a re w ithin the a llo w a b le lim its ts.. 2. Sol olve ve dyna dyna mi mic c p rob lems d evel evelop op ed d ue to t o me c hani hanic c a l vi vib b ra ti tion, on, flui fl uid d ha m m e r, pul p uls sa ti tio o n, etc . 3. Sol olve ve the p rob lem s a ssoc ia ted d ue to hi hig g her or low er tem p er era a tur tures es.. When piping is connected to strain sensitive equipment, the flexibility required to satisfy the acceptable limits of nozzle loading on the c o nne c te d e q ui uip p m e nt ove rrid e s a ll o the r c o ns nsiid e ra ti tio o ns ns.. The p ip ing sys yste te m s a re m a inl nly y c la ssifi fie e d int nto o 3 m a in c a te g o rie s a nd the n a g a in sub sub -c a te g o rie s. The m a in c a te g o rie s a re HO T Sys yste te m s, CO LD Sys ystt e m s a nd C RYO G ENI NIC C Sys ystt e m s. In In th thiis t he ho t a nd c ryo g e nic line lin e s m u st u n d e rg o FLEXIB IBIL ILT TY ANA A NA LYSIS.
UIR REM ENT O F STRESS A NA LYS LYSIIS • REQ UI
No formal stress analysis is required if: • The p ip ing sys yste te m is d up lic a te o f suc suc c e ssful fullly op e ra ti ting ng ins nsta ta lla ti tio o ns o r replacements. • Ca n be rea rea d ily a d judg ed a d eq uatel uately y b y c om p a rison with with p revi evious ouslly a na lys yse e d sys ystt e m s. • Sa ti tis sfy eq ua ti tio o n Sp Sp e c ifi fie e d in the c la us use e 119.7.1(A3 (A3)) / 319.4.1(c ).
BASIC I NFO NFORM RM AT ATION ION
A set of piping general (GAD) A Complete set of steel & structural drgs including the equipment foundation. A set of drgs showing the location of ventilating ducts, electrical trays, instrument trays etc. A set of piping spec and line list, which includes pipe sizes, M.O.C., thickness of insulation, operating temperatures etc. A copy of insulation spec. With densities. A copy of valve and specially list indicating weights. The movement of all critical equipment connections such as turbines, compressors, boilers etc.
ON COLLECTION OF THE ABOVE DATA, THE STEPS IN WHICH THE PIPE STRESS ENGINEER WILL APPLY THIS BASICS TO DESIGN THE PIPING SUPPORT SYSTEM .
The determation of support location. The determination of thermal movement of the piping at each support location. The calculation of load at each support location. The selection of load at each support location. The selection of type of support i.e. Anchor, Guide, Rest, Constant or Variable Spring etc. Checking physical interference of the support with structures, trays, ducts eqpts etc
• Ex Exce cess ssiv ive e dis isto tort rtio ion n su sub bje ject ct to cr cree eep p un unde derr co cond ndit itio ions ns of repeated thermal cycling. • Ex Exce cess ssiv ive e hea heatt flo flow, w, ex expo posi sing ng su sup ppo port rtin ing g ele eleme ment ntss to to temperature extremes outside their design limits.
Support Drawing Samples
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