EN13480-3 Current Status

8/9/2019 EN13480-3 Current Status

1/14

Currentsta

tusoftheD

INEN1348

0-3

Metallicindustrial

pipingDes

ignsandcalcu

lation

Dr.-Ing.Joch

enWeber

BHRHochdruc

k-Rohrleitungs

bau

GmbH,Essen

Dr.-Ing.Heinz

-WilhelmLan

ge

LISEGAAG,Ze

ven

T+++BHR

-REPRINT+

++BHR-REP

RINT+++BHR-REP

RINT+++

BHR-REPR


2/14

FACHBERICHTE

26 3R international (48) Issue 5/2009

Dr. Jochen Weber, Dr. Heinz-Wilhelm Lange

This article reports on the current status of the EN 13480-3. Information was also providedon this subject at the 24th FDBR Conference of Piping Technology in March 2009 inMagdeburg, Germany. The code was published in the year 2002 and was at first appliedwith some hesitation, but is now widely followed. To create a common European codeMetallic industrial piping systems Design and calculation, which has grown out of avariety of national guidelines, was an impressive feat by all those involved, which will not bedepreciated or placed in question here. However, as is to be expected with such a new andcomplex set of rules, some weak points and errors became evident in its implementation.The FDBR working group Festigkeitsberechnung / Technische Regelwerke (StrengthCalculation and Technical Codes) has identified these errors and elaborated correctivesuggestions.On the occasion of the 22ndPlenary Session of the CEN/TC267 in November 2008 it wasagreed that this year, 2009, an updated working version of the norm will first be created.This forms the basis of the planned publication of a revised edition of the EN 13480-3 inthe first quarter of 2010. Unfortunately, at the moment very few European countries areparticipating in the revision of the code.

Dieser Beitrag berichtet ber den aktuellen Stand der EN 13480-3, ber dieses Themawurde auch im Rahmen der 24. FDBR-Fachtagung Rohrleitungstechnik (Rohrleitungstech-nische Tagung) im Mrz 2009 in Magdeburg berichtet. Die Norm wurde im Jahre 2002verffentlicht und zunchst nur zgerlich, mittlerweile aber doch auf breiter Front, an-gewendet. Eine gemeinsame europische Norm Metallische industrielle Rohrleitungen Konstruktion und Berechnung zu erstellen, die aus verschiedenen nationalen Regel-werken zusammengewachsen ist, war eine groe Leistung aller daran Beteiligten, die hierauch nicht geschmlert oder gar in Frage gestellt werden soll. Trotzdem, wie bei einemsolch komplexen, neuen Regelwerk nicht anders zu erwarten, zeigten sich bei der Anwen-dung einige Schwachstellen und Fehler. Der FDBR-Arbeitskreis Festigkeitsberechnung /

Technische Regelwerke hat diese Fehler gesammelt und Korrekturvorschlge erarbeitet.Anlsslich der 22. Plenarsitzung des CEN/TC267 im November 2008 wurde vereinbart,dass in diesem Jahr 2009 zunchst eine aktualisierte Arbeitsversion der Norm erstelltwird. Diese bildet die Grundlage dafr, dass im 1. Quartal 2010 eine berarbeitete Ausgabeder EN 13480-3 verffentlicht werden kann. Leider beteiligen sich derzeit nur sehr wenigeeuropische Lnder an der berarbeitung der Norm.

The technical committee CEN/TC267, whose

office is run by AFNOR in Paris, is responsib-le for the elaboration of the EN 13480 part1 to 8. AFNOR also runs the offices of WG3,responsible for EN 13480-3, and WG8, themaintenance group.

The final draft version of the EN 13480-3 wasadopted by the working group responsible,CEN/TC 267/WGC (now renamed WG3) inOctober 2001. Four to five German expertswere permanently active in WGC. This paper

finally went through the obligatory editorialrevision by an editing committee whose aimwas to examine compliance with the formalguidelines of the CEN concerning Europeanstandards and if necessary to make correc-

tions. In this phase of the revision, however,a large number of printing errors, particular-ly with regard to equations and illustrations,were unfortunately made.

The first issue in German language appearedas DIN EN 13480-3 in August 2002. Since itwas produced under some pressure of timeit contains a number of language inconsis-tencies which additionally complicate its ap-plication. Immediately after publication of thestandard a help desk was set up at TC267(WG8) with the aim of answering any querieswithin 30 days.

A committee in Germany which dealt veryrapidly with the deficiencies of EN 13480-3is the FDBR working group Rohrleitungen(Piping). Its achievement is the legendarybulletin FDBR-MB 7, which contains initialsuggestions for correction. All the correc-tions and suggestions from German sourceswere collected and processed in the FDBRworking group Festigkeitsberechnung undTechnische Regelwerke (Strength Calculati-on and Technical Codes). This working grouphas in the meantime become the official Ger-man mirror committee to CEN/TC267, as

the joint working group FDBR Festigkeitsbe-rechnung und Technische Regelwerke / DINNA082-00-17 AA Rohrleitungen (StrengthCalculation and Technical Codes / DINNA082-00-17 AA Piping). The processed re-quests for modifications were forwarded toCEN/TC267 and on the whole accepted.

Supplements and technical changes in thestandard can be made by way of amend-ments. These supplements to the stan-dard are then usually voted on followinga unique acceptance procedure (UAP) bythe member states. The UAP is a single

stage acceptance procedure; the amend-ment prepared will be brought forward forwritten approval throughout Europe withina limited period of time. The appendicesO and P are originated in this manner;

Origination, historyand current status

Current status of the DIN EN 13480-3

Metallic industrial piping Designs and calculation

2


3/14

FACHBERICHTE

273R international (48) Issue 5/2009

Appendix Q is currently under debate. Theappendices will be dealt with later.

All amendments so far made are availablefree of charge from the publishers Beuth.

On the occasion of the 21stPlenary Sessionof the CEN/TC267 in November 2007 it wasdecided to revise all parts of the EN 13480.

The target date for the new issue of the EN13480-3 is the first quarter of 2010.

In the following the essential correctionsand supplements to various sections of thestandard, as well as the appendices, are de-scribed. The treatment of the section PipeSupports then follows, with the relevant ap-pendices.

Section 6.4 Reducers

Section 6.4, Reducers, was taken over fromthe British Standard BS 5500 (PD 5500 to-day) [1]. The authors of EN 13480-3 haveendeavoured to adopt additional equationsand explanations as against BS 5500 in thissection. For example, equations allowing thedetermination of the permissible pressurePS of a reducer were added that is practi-cally the test as to whether the design hasbeen carried out correctly. However, thesesupplementary passages are in part moreconfusing than helpful.

Two fundamental problems arise with the di-mensioning of a reducer:

The procedure required for the dimen-sioning does not correspond to the se-quence in which the equations are noted.First the cylindrical components of the re-ducer (large and small diameter) must bedimensioned according to the equationsin Section 6.1. After that the characteris-tic diameter DK is determined, for whichsome equations from Sections 6.4.5 and6.4.6 or 6.4.7 have to be evaluated be-fore the wall thickness of the cone can becalculated according to Section 6.4.4.

The results are in part determined ite-ratively, by making assumptions of wallthickness which are then confirmed orcorrected by evaluating equations. Thisleads amongst other things to calculationprograms producing different results, de-pending on the grade of accuracy of theiteration performed this again has led todiscussions with notified bodies.

A further problem arises if only minor dif-ferences in nominal diameters are to beconnected by means of a reducer. In thesecases the required length 2l2between two

cylinder/cone connections cannot always bemaintained. Therefore notified bodies undercertain circumstances may demand a diffe-rent proof, which ends up with FEM analysesbeing carried out.

From the results of such FEM analyses thesuggestion was made to dispense undercertain circumstances with the length 2l2between cylinder/cone connections without

additional proof.The suggestion accepted in the meantimeby CEN/TC267 intends additionally insertingthe following text into Section 6.4.5:

The length of the cone can be reduced toless than 2l2 if both of the following con-ditions are fulfilled.

The wall thickness e2, calculated in ac-cordance with 6.4.6 or 6.4.7, is existentalong the whole length of the cone.

The junction at the small end of the cone is

sufficiently dimensioned according to 6.4.8.FEM analyses performed indicate that ashortening of the cone to a length smallerthan the required dimension 2l2is permissibleunder the boundary conditions mentioned. Inthis way the dimensioning of reductions ofminor diameter differences according to EN13480-3 is possible.

In section Section 6.4.10, Special forgedreducers, the equation lacking till now(6.4.10-5) is added, as well as an explana-tion:

er= max (ecyl:ej) ( 6 . 4 . 1 0 - 5 )with ecyl according to Section 6.1 and ejaccording to Eq. (6.4.7-4)

In Fig. 6.4.10-1 a number of minor correc-tions were made. An alternative componentdesign is included as Fig. 6.4.10-2 Fig. 1.

Section 8.4Isolated openings

The calculation of oblique nozzles should

proceed analogously to TRD 301 [9] or TRD303 and thereby also correspond to thecalculation rules set out in EN 12952-3.This proposal by the German delegationwas accepted as early as 1996 in the WGC.

However, the corresponding figures did notactually appear in the drafts until spring2001. In the final stage of work on the stan-dard, in the Editing Committee, the wrong

figures were inserted again and an additio-nal area APbdefined Fig. 2, compare Fig.8.3-1 in EN 12952-3 with Fig. 8.4.3-3 in EN13480-3 and Fig. 3, compare Fig. 8.3-2 inEN 12952-3 with Fig. 8.4.3-4 in EN 13480-3.After the 22ndCEN/TC267 plenary sessionin November 2008, the justified hope existsthat this error can now be finally correctedwithout applying to CEN for a work item, asthe TC267 has accepted the fact that onlyan editorial error and not an error in contentwas made.

Section 12.3 Flexibility analysis

The fundamental equations for the perfor-mance of the flexibility analysis were adop-ted from the FDBR guideline [10] Design ofPower Piping. The safety factor against mini-mum tensile strength was thereby reducedfrom 4.0 to 3.0, which at moderate calcula-tion temperatures leads to an increase in thestress limit fhover the previous Shand alsothereby to an increase in faas against Sa. Inthis way the limit for secondary stresses wasraised, while at the same time, however, the

limit for the primary stresses resulting fromthe limitation to fh instead of the earlier Smwas lowered.

The Germans made the suggestion that anew symbol ff design stress for flexibilityanalysis should be introduced. This propo-sal, already accepted in the TC267, aims atrestoring the old limitation for the primarystresses.

Problem

In EN 13480-3, fh is applied, instead of thevalue Smof the FDBR guideline [10].

In some cases the definition of fhin Section 12leads to more restrictive stress limits than thesource of this Section, the FDBR guideline [10]

Bild 1:Geschmie-dete Spezialre-duzierstcke,alternative Bauform(Vorschlag) [Bild6.4.10-2]

Fig. 1:Specialforged reducers,alternative solution

(proposal) [Fig.6.4.10-2]

3


4/14

FACHBERICHTE


Design of Power Piping. This applies es-pecially to non-austenitic steels at moderateoperating temperatures. A typical exampleis the HP feed water piping made of 15Ni-CuMoNb5-6-4 (WB36), see the followingexample.

FDBR guideline:

EN 13480-3:

* resulting from fh= min. (fc;f;fcr) (12.1.3-3)

Proposal

A new symbol ffshould be introduced.

ff- Design stress for flexibility analyses(flexibility calculations) in N/mm (MPa)

with ff= min (f; fCR).

ff is applied in the equations (12.3.2-1,(12.3.3-1) and (12.3.3-2) instead of fh.

Justification

In accordance with the pressure equipmentdirective (PED) the stress limit Rm/2,4 ap-plies for the dimensioning of componentsbased on membrane stresses. The sum ofmembrane and bending stresses in the flexi-bility analysis should not be limited to a lower

value.The example in Table 1 shows the conse-quences of this alteration for piping made ofthe material 15NiCuMoNb5-6-4 at TS = 300C. The permissible stresses for the evalua-tion of sustained loads and the sum of susta-ined and occasional or exceptional loads arethereby raised again to the level of the FDBRguideline [10]. The permissible stresses forthe evaluation of alternating secondary loadsare in this case increased compared to theFDBR guideline, which can be ascribedto the above-mentioned reduction of the

safety factor.

Amendment 1: 2005-11,Annex O (normative)

Alternative procedure for thetesting of branch connections

In Section 8, Openings and branch connec-tions, a reference to the normative AnnexO was adopted, which contains an alter-native calculation procedure for openings,opening reinforcements and branches.The procedure described in Annex O isbased on limit load design and shakedown;

Bild 2:SchrgerAbzweig, axialgeneigt in EN13480-3 (links)und EN 12952-3(rechts)

Fig. 2:Obliquebranch, axialinclination in EN

13480-3 (left side)and EN 12952-3(right side)

Bild 3:Schrger Abzweig, tangential geneigt in EN 13480-3 (links) und EN 12952-3 (rechts)Fig. 3:Oblique branch, tangential inclination in EN 13480-3 (left side) and EN 12952-3 (right side)

Tab. 1:Spannungsbegrenzungen fr Werkstoff 15NiCuMoNb5-6-4 bei TS = 300 C nach EN 13480-3, FDBR-Richtlinie und nderungsvorschlag zu EN 13480-3

Table 1:Stress boundaries for material 15NiCuMoNb5-6-4 at TS = 300 C acc. to EN 13480-3, FDBR-Guide-line and proposed change to EN 13480-3

EN 13480-3 FDBR guideline Proposal

Primary stressesEq. (12.3.2-1)

fh= 203 MPa Sm= 254 MPa ff= 254 MPa

Primary stresses sustained +occasional Eq. (12.3.3-1)

k fh= k 203 MPa k Sm= k 254 MPa k ff= k 254 MPa

Secondary stressesEq. (12.3.4-1)

fa= 276 MPa Sa= 207 MPa fa= 276 MPa

Primary and secondary stressesEq. (12.3.4-2)

fh+ fa= 479 MPa Sm+ Sa = 461 MPa ff+ fa = 530 MPa

4

Zone I Zone II


5/14

FACHBERICHTE


unfortunately, no mention of sources (litera-ture) was made. The following advantagesas against the standard procedure in section8 were distinguished:

Especially suitable for large openings

Consideration of bending and torsion mo-ments is possible in addition to considera-

tion of the internal pressure.The second statement must be put into per-spective. Bending and torsion moments arecurrently considered according to Section12, so here it is simply a question of a diffe-rent evaluation procedure.

The procedure must not be applied to bran-ches used in the creep range. In Annex O itis additionally pointed out that this calcula-tion is applicable for loads of predominatelynon-cyclic nature. However, indications arelacking of necessary reinforcing lengths ordistances between openings.

Annex O has been agreed to by way of UAP.

The German mirror committee DINNA082-00-17 AA represented for the mostpart by FDBR working group Strength Calcu-lation and Technical Codes has attemptedto obstruct Annex O, or at least have a morethorough professional examination made, asmisgivings exist concerning the applicationof the procedure to openings in thin-walledshells.

Germany was the only European country toreject Annex O in this form. However, as theUAP had already been initiated at this junc-ture, only the obvious errors in equationsand diagrams could be corrected.

The equations (O.3.1-1) and (O.3.1-2) for de-termining the permissible pressure in straightpiping should not be applied. The pressuresthereby calculated lead to Tresca equivalentstresses in the piping which amount to ap-proximately 1.15 Rp0,2t, that is, to pressuresat which plastification / yielding sets in.

However, the equation (O.3.2-3), for example,supplies the same wall thickness required for

c = 1.0 (pipe without opening) in accordancewith section 6.1.

Tables 2 and 3 show a comparison bet-ween the calculation procedures on thebasis of several examples. Specified meandiameters of run pipe and branch were assu-med, as well as the specified wall thicknessof the branch. The required wall thickness ofthe run pipe was calculated. The permissiblestress is f = 90 MPa in all examples.

The symbols esand ebstand for determinedwall thickness. If measured wall thicknessesare meant by this, the results in Table 3are correct. If however calculated wall thick-nesses are meant, an iterative procedure isrequired, since the weakening coefficientschange dependently on the wall thicknes-ses.

The examples show that, for thin-walledbranches, in part considerably smaller wallthicknesses are determined than with thestandard procedure according to Section 8.As a comparison the calculation according

to ASME B31.1[3] was also included. Thedeviations between EN 13480-3 and ASME

B31.1 are substantiated by using either theKellogg-method (EN 13480-3) or the areareplacement method (ASME B31.1) and arewell known.

Conclusion:the misgivings that non-conser-vative results ensue from openings in thin-walled shells have been confirmed at least inpart, but the results do not deviate as widelyas according to ASME B31.1. It was not ex-amined here what differences appear in theevaluation of bending and torsion momentsin comparison to Section 12.

Amendment 2: 2007-02,Annex P (informative)

Bolted flange connections Application of EN 1591

The first issue of EN 13480-3 treats thecalculation of flange connections in a verynegligent fashion in section 6.6 Bolted flangeconnections. Only three possibilities areshown there to evaluate the strength beha-viour of a flange connection.

Tab. 3:Vergleich EN 13480-3 Abschnitt 8, Anhang O und ASME B31.1 Ergebnisse

Table 3:Comparison EN 13480-3 clause 8, Annex O and ASME B31.1 results

Tab. 2:Vergleich EN 13480-3 Abschnitt 8, Anhang O und ASME B31.1 Abmessungen und Berechnungsdr-cke

Table 2:Comparison EN 13480-3 clause 8, Annex O and ASME B31.1 dimensions and calculation pressures

Example No.Dm

in mmdm

in mmes

in mmeb

in mmpc

in MPa

1 200 80 20 20 16.78

2 400 200 20 10 4.950

3 400 200 10 5 2.057

4 400 200 10 15 3.603

5 2000 300 20 4 1.059

6 2000 1000 20 10 0.616

7 2000 2000 20 20 0.533

Example No. dm/ Dm Dm/ es eb/ es

esaccordingto Section 8

in mm

esaccordingto Annex O

in mm

DeviationAnnex O

esaccording toASME B31.1

in mm

DeviationASME B31.1

1 0.4 10 1.0 20.0 20.86 +4.3% 19.5 -2.5%

2 0.5 20 0.5 20.0 18.02 -9.9% 21.6 +8.0%

3 0.5 40 0.5 10.0 8.95 -10.5% 8.9 -11.0%

4 0.5 40 1.5 10.0 9.96 -0.2% 12.6 +26.0%

5 0.15 100 0,2 20.0 14.85 -25.7% 23.6 +18.0%6 0.5 100 0.5 20.0 19.22 -3.9% 13.4 -33.0%

7 1.0 100 1.0 20.0 17.89 -10.6% 11.7 *) -41.5%

*) Wall thickness ebalso has to be 11.7 mm.

5


6/14

FACHBERICHTE


Selection according P-T ratings, i.e. appli-cation of EN 1092

Application of the Taylor-Forge Method,see also EN 13480-3 Annex D (normati-ve)

Application of EN 1591 if special de-mands concerning leak tightness are tobe considered

It is well known that the calculation of DINflange connections according to the Taylor-Forge Method does not usually work. With

the application of EN 1591, the stress ana-lyst was left out in the rain for a long time,because the EN 1591-1 may describethe procedure for calculation, but the EN1591-2, which is to supply the required cha-racteristic gasket properties, was on handfor some time, but only as an incompletedraft. Just as a reminder the characteristicgasket properties used till now for calcula-tions according to AD 2000 bulletin B7 andB8 [11] or DIN V 2505 [12] are insufficientfor calculation according to EN 1591.

It was attempted with the informative Annex

P to close this gap and to better establishthe application of EN 1591 in piping con-struction. In addition, Annex P contains arange of characteristic gasket propertieswith which the application of EN 1591-1 is atall made possible.

The formulation in Section 6.6 renderedmore rigorous by the integration of Annex Pis unfortunately worded, in the authors opi-nion: If a standard flange is specified in aEuropean standard, and no further require-ment is given, the flange shall be selectedby means of the P/T rating. In this way it

is implicitly forbidden to reflect both on animplementation going beyond the P-T ratingsas well as on the strength and tightness be-haviour of the flange connection, which isalso dependent in the end on bolts and gas-

ket. It would be better to say at this juncture:the flange may be selected insofar asapplicable according to the pressure-tem-perature rating.

Annex P was also agreed to by way of UAP.

Annex P contains:

Instructions on the application of EN

1591

Recommended gasket materials for indus-trial piping systems

Characteristic gasket properties, main-ly for soft material gaskets as well asgrooved gaskets with graphite covering.

Amendment 3: 2009-1,various alterations

Amendment 3 contains corrections to Sec-tion 2, to the sub-Sections 8.4.3, 13.1.4,

13.3.1, C.1.1, D.4.1 E.2.1.1, as well as toAnnexes H and N and the literature index,and was accepted per UAP in April 2008.

Amendment 4: UAP,started up in 2009-4,Annex Q (informative)

Simplified pipe stress analysis

Till now, EN 13480-3 contains no rules forsimplified stress analysis (routing guideline),as is normal in other rules and standards.The draft of the standard contained at leasta table of allowable width between supportsbut was not included in the first edition in2002. Annex Q originated from a Germanproposal. This annex contains a calculationmethod for determining the permissiblewidths between supports, as well as a flexi-bility check.

The calculation methods correspond to theprocedure as defined in TRR 100 and in AD2000 bulletin HP 100 R [11]. The tablesof allowable widths between support wererevised; the values given in Annex Q differslightly from those in AD 2000 bulletin HP100 R.

Section 13: Supports

One of the biggest construction sites in EN13480-3 in Section 13, with the correspon-ding Annexes. In the changes, differentiationis made between

[ ge ] = general

[ te ] = technical

[ ed ] = editorial

[ tr ] = translation

If the number of changes in Section 13 iscompared with the other parts of the stan-dard, above-average changes are necessary.

Large parts are translation errors or unhap-pily phrased translations that change thesense of the text. In the German version thetitle is Absttzungen the literal translationof the English title Supports. Normally, allpipe-holding components, i.e. supports andhangers, are described as supports in Eng-lish language usage the more meaningful

German translation is Rohrhalterungen (lit.:pipe holders).

A few examples should demonstrate how in-appropriate terms and translations can con-fuse the reader.

In the legend of (Fig. 4) Spring supportto steel intermediate structures [Figure13.1.4.-2] the following explanations are tobe found:

(A) pipe(B1) pipe clamp(B2) pipe support(B3) secondary or intermediate steelworkto

be built in by the support manufacturer(C) steelworkEven a glance at the original English ver-sion of the standard does not help us muchfurther:(B3) secondary or intermediate steelwork

to be constructed by the supportmanufacturer

A number of unfortunate circumstances coin-cide here: the German translation is certainlynot what the originators of the standard in-tended. A literal fulfillment of the standard,often generally demanded in specifications,leads in cases of doubt to discussions con-cerning the different shipments, consideringthat the intermediate steelwork could undercertain circumstances lie within the field ofbuilding law.

A further example of confusing formulationsin Section 13.1.3 Supplementary terms isthe definition

13.1.3.1. Verankerung: starre Vorrichtung,die an der Sttzstelle die gesamte relativeVerdrehung und Verschiebung der Rohrlei-

tung bei Auslegungstemperatur und -belas-tung verhindert und selbst Bewegungen un-terworfen sein kann.

(13.1.3.1 anchorage: rigid device, usedto prevent all relative pipe rotation and dis-placement at the point of application underthe design conditions of temperature andloading and which may itself be subject toimposed displacement.)

A look at the English version shows whattype of pipe support is actually meant:

13.1.3.1. anchor: rigid device, which may

itself be subject to imposed displacement,used to prevent all relative pipe rotation anddisplacement at the point of application, un-der the design conditions of temperatureand loading.

Bild 4: Verbindung von Federhnger undZwischentragwerkskonstruktion [Bild 13.1.4-2]

Fig. 4:Spring support to steel Intermediatestructures [Figure 13.14.4-2]

6


7/14

FACHBERICHTE


By anchor, fixed points are normally meant.Reading the text, one is inclined to think ofthe famous comment but it does move!.During the discussion in working group 3 ofTC 267 the formulation und selbst Be-wegungen unterworfen sein kann (... andmay itself be subject to displacement) was

explained. Connection points on vessels orsimilar are thereby meant; in some calcula-tion programs these are defined in a similarway to anchors. In the next edition anchors,as generally accepted, are so defined:

13.1.3.1 Festpunkt: starre Vorrichtung, diean der Sttzstelle die gesamte relative Ver-drehung und Verschiebung der Rohrleitungbei Auslegungstemperatur und -belastungverhindert.

(13.1.3.1 Fixed point: rigid device, usedto prevent all relative pipe rotation and dis-placement at the point of application, underthe design conditions of temperature andloading.)

The list of corrections to the German trans-lation is fairly copious. As a final exampleof translation errors, the definition of rigid

struts should be mentioned here:

13.1.3.9 Gelenkstrebe: Einrichtung, die dieRohrleitung in einer Ebene hlt; gilt blicher-weise fr dynamische Belastung.

(13.1.3.9 Rigid strut: device to restrain thepiping in a plane, applies generally to dyna-mic loading.)

The English original describes the function ofrigid struts more clearly, for rigid struts actonly in one direction.

13.1.3.9 Rigid strut: device to restrain the

piping in a single direction, generally duringdynamic loading.

Here too, in the next version of the standarda common definition is used:

13.1.3.9 Gelenkstrebe: Einrichtung, die dieRohrleitung in einer Richtung hlt und bli-cherweise fr dynamische Belastung einge-setzt wird.

(13.1.3.9 Rigid strut: device to restrain the

Bild 5: An das Rohr angeschweite Absttzung[Bild 13.1.5-1] (akt. Norm / nderungsvorschlag)

Fig. 5:Support welded to the piping [Figure13.1.5-1] (act. Standard / modification proposal)

Bild 6: Verbindung zu Stahltragwerk [Bild 13.1.4-1] (akt. Norm)

Fig. 6:Connections to steel structures [Figure13.1.4.-1] (act. Standard)

piping in a single direction, in many casesused for dynamic loading.)

Additionally, in the definition part of Section13 some details not generally included areshown in the illustrations. For example (Fig.5) Support welded to the piping [Figure13.1.5-1] shows two weld seams.

In pipe supports with NB 900 it is possibleup to a certain length to weld the pipe sup-port to the pipe, as shown in the diagram onthe left. In general, however, it will be a mat-ter of a fillet weld or a full penetration weld.

Key: (A) Pipe (B) Pipe Support (C) Steel structure

7


8/14

FACHBERICHTE


It is a similar case with (Fig. 6) Connec-tions to steel structures [Figure 13.1.4-1]in which an anchor (fixed point), is shownas a special design. Most users of the stan-dard will, however, use standardized pipesupports as far as possible. Such a figureplaced exclusively in the definition part leadsto confusion amongst less experienced pipesystem designers. The figure was discussedintensively in working group 3. The Frenchdelegation insisted on keeping this figure inthe definition, as it is also presented in this

form in CODETI [4]. As a compromise, in thenext version of the standard a support ofstandardized components will be displayedbeside the anchor as a special design, asshown in (Fig. 7).

Section 13.3.7: Determinationof component sizes

Greater modifications were necessary in theSection Determination of component sizes.In Section 13.3.7.3 Stresses, the followingdefinition is to be found:

The individual or equivalent stresses mustnot exceed the permissible stresses givenin [Table 13.3.7-1] and [13.3.7-2]. The value

of the combined stress e must fulfill thefollowing equation:

Therebyais the calculated axial (membrane) stressbis the calculated bending stresssis the calculated shear stress

Within this brief definition two different termsequivalent stress and combined stressare used for equivalent stress. The use of

the Tresca-equivalent stress is actuallyuncommon in mechanical engineering; inother rules and standards (VGB R510 L [13],KTA 3205.3 [14]) the determination of thevon-Mises equivalent stress is required. Inthe revision of this section the normally-usedsymbol was used for shear stress. In thelatest internal working version distributedin the TC 267, the standard (English ver-sion) is found as a definition of the equivalentstress:

The permissible stresses are defined in Sec-tion 13.3.7.2. It is a question thereby of twodifferent definitions:

(design in the yield stress range / time-inde-pendent design) and

(for components with a design temperaturein the creep range / time-dependent design)

For components designed in the yield stressrange (time-independent design) the usual sa-fety level is required. The permissible stressin the creep range (time-dependent design)fCR is defined in Section 5 [Eq. 5.3.2-1]:

fCR= SR 200,000t/ 1.25

with SR 200,000t as the mean creep rupturestrength according to the material standardat calculation temperature t and an observedlife of 200,000h (whereby the usual devia-tion of max. 20 % of the mean value isrequired).

The permissible stress in the creep range isthereby

fCR= 0.8 mean creep rupture strength at200,000h or

fCR = min. creep rupture strength at200,000h

It is a question thereby of the usual defini-tion for the piping calculations. For pipe sup-ports an additional safety factor of 1.25 isrequired:

f = 0.64 mean creep rupture strength at

200,000h orf = 0.8 min. creep rupture strength at200,000h

This requirement is definitely unusual andleads to unnecessarily oversized compo-nents compared with the design accordingto VGB R 510 L. The reason for this uneco-nomic requirement is only evident in the fol-lowing definitions. In Sections 13.3.7.3 and13.3.7.4 different permissible stresses aredefined for linear supports and plate andshell supports. The definitions of the two dif-ferent types are:

Linear supports can be calculated accor-ding to the beam theory and the relevantpermissible stresses must correspond to[Table 13.3.7-1].

Plate and shell supports are made from flatbars and plates and cannot be calculated ac-cording to the beam theory; the relevant per-missible stresses must correspond to [Table13.3.7-2].

In Table 4 the permissible stresses from[Table 13.3.7-1] and [Table 13.3.7-2] fornormal operating conditions are compared.

A direct comparison shows that by applica-tion of the shell / plate theory the permissi-ble bending stress lies 50% above the usuallevel.

Bild 7:Verbindung zu Stahltragwerk [Bild 13.1.4-1] (nderungsvorschlag)

Fig. 7:Connections to steel structures [Figure 13.1.4.-1] (modification proposal)

Tab. 4: Zulssige Spannungen fr normale Betriebsbedingungen (akt. Norm)

Table 4:Permissible stress for normal operating conditions (act. Standard)

Type of stress

Permissible stresses (normal operating conditions)

Linear supports Plate and shell supports

Tension a 1.0 f 1.0 f

Bending b 1.0 f 1.5 f (!!!)

Shear 0.5 f 0.5 f

Equivalent e 1.0 f 1.5 f (!!!)

Key: (A) pipe (B) pipe support (e.g. clamp base) (C) structure

(B) pipe support (B2) pipe support (e.g. intermediate steel)

Pipe support made of standard components Customised pipe support

8


9/14

FACHBERICHTE


On closer observation the following stresslevel is produced with the definition of f (f =fCR/1.25):

1.5 f = 0.96 mean creep rupture strengthat 200,000h or

1.5 f = 1.2 min. creep rupture strength at200,000h.

These factors actually speak for themselvesand need no further explanation. The rea-son for these questionable definitions istheir 1:1 adoption from the French standardCODETI.

The German modification proposal no longerdifferentiates between the applied calcula-tion theory; the permissible stress is definedas usual as:

The limits shown in Table 5 then result forthe individual stresses.

The modification of the max. shear stress isthereby the consequence from the changefrom the Tresca equivalent stress to thevon-Mises equivalent stress. The permis-sible stresses for occasionally operating con-ditions amount to 1.2 times the permissiblestresses for normal operating conditions.

For pipe supports NOT used in the creep range

(time independent design), higher bendingand equivalent stresses are permissible:

For pipe supports analyzed with the plateor shell theory

normal operating conditions:b1.5 f, e1.5 f

For double symmetrical solid sections normal operating conditions:b1.1 f, e1.1 f

Section 13.5.1.2: Constant

hangers/supportsIn the current issue of EN 13480-3 thefollowing requirement is made in Section13.5.1.2 Constant hangers/supports:

Constant hangers/supports must be able toresist lateral thrusts of up to 30% of the no-minal load. If higher lateral thrusts are expec-ted, then the use of sliding surfaces should

be considered in the design.The requirement Constant hangers must re-sist a lateral thrust of 30% is unrealistic, asthe deflection of the tension rods is limitedto 4 - that corresponds to approx. 7% ofthe vertical load. In this section the Germanand English versions of the standard differ.In the English versions only base mountedsupports are mentioned. The requirement30% lateral thrust/load is, compared with

German regulations, unusual and unrealistic.Theoretically, constant supports can be con-sidered for such high lateral thrusts. Due tothe internal friction they would have a hyste-

resis exceeding the usual requirement loaddeviation max. 5%. All conceivable designmeasures (independently of the hangersfunction principle) would be out of all propor-tion to the use of suitable sliding surfaces(e.g. PTFE).

The following formulation was proposed bythe German mirror committee: Constanthangers must be designed for oblique ten-sion of 4 %.

Bild 8:Einstellbereich fr Konstantsttzen [Bild I.1-2]

Fig. 8:Adjustment range for constant load support [Figure I.1-2]

Bild 9:Einstellbe-reich fr Federstt-

zen [Bild I.2-1]Fig. 9:Adjustmentrange for variablespring supports[Figure I.2-1]

Tab. 5: Zulssige Spannungen fr normale Be-triebsbedingungen (nderungsvorschlag)

Table 5:Permissible stress for normal operatingconditions (modification proposal)

Type of stress Permissible stress(normal operating

conditions)

Tension

a 1.0 fBending b 1.0 f

Shear 0.6 f

Equivalent e 1.0 f

maximum hanger load

possible re-adjustment +15 %

FD.maxmaximum hanger load

scheduled adjustment range

possible re-adjustment -15 %

min. adjustment load

9

FD.minmin. adjustment load

FN= 1,15 FD.max

Fmin= 0,85 FD.min


10/14


11/14

FACHBERICHTE


Table 6defines the Rated load derived bytesting [Table J.4-1]. At first glance this tablereminds us of German codes. However, thelast line but one is strange: buckling safetyof 4 or 2.4 K1is demanded for anchor ten-sion rods thereby K1is the ratio between thetensile strength of the material used and thevalues in the material standard. The physical

relationship between buckling and tensilestrength is not easy to detect. A look at theEnglish version shows that instead of anchortension rods the term rods is used, where-by tension rods are meant. In this connectiona buckling load is really meaningless.

A number of clearer formulations were there-fore included in the revision.

As permissible rated load the smallest testload determined is to be used in which thefailure limit (ultimate failure load FU), yieldlimit (yield load FY), buckling limit (bucklingload FB) or stability limit (stability load FS) is

reached, whereby the lowest value accor-ding to Table J.4-1 is to be applied for thecorresponding component.

In addition, an explanation in respect of thestability load was included:

Note: Failure through instability can occurin various forms such as buckling, lateralbuckling, lateral torsional buckling, plate/shell buckling in the elastic as well as theplastic range.

The table was adjusted to the usual require-ments (Table 7).

Annex L: Buckling ofrod-like supports

The informative Annex L treats buckling ofrod-like supports. The reader can be con-fused in the fundamental equations by unfor-tunately chosen symbols or by typing errors.The radius of gyration is as usual defined as

. The buckling length of therod-like support is calculated as lb= K I (with

K = {0.5; 0.7;1;2}). Here the length L ofthe support should be used. The slender-ness ratio is defined as = lb/ and is tobe smaller than 200. The calculation proce-dure distinguishes between elastic bucklingand plastic or elastoplastic buckling. Elasticbuckling begins at slenderness ratios c.The permissible compression stress is de-fined for both ranges:

The formula a (< c) contains an error:in the last term, in the denominator the fac-tor 1/8 is missing. By comparing differentcodes, e.g. ASME BPVC [5] and AISC [6](USA) RCCM [7] CODETI [4] (FR) it is clearthat this error has crept in from the inclu-sion of the equations in the French stan-dard CODETI. The representation of the twoequations as a diagram reveals the mistake(Figure 12).

The diagrams in [Table L.5-1] had in largepart to be revised, as the boundary values ofthe buckling-deflection lines were unclearly

or wrongly presented. As an example, a va-riant of the third Euler buckling case (rotatio-nal spring instead of rigid fixation) is shown.At both ends the buckling-deflection line isshown with a horizontal tangent, but an in-

clination of the deflection line is possible atboth base supports (Figure 13).

The correction of the last section of An-nex L is particularly complex: Checking ofbuckling safety for components which at thesame time are loaded with axial compressi-on stress and bending moments.

Bild 12:Zulssige Druckspannung in Abhngigkeitvom Schlankheitsgrad

Fig. 12:Permissible compression stress in depen-dence of slenderness ratio

Tab. 6:Durch Prfung ermittelte Nennlast [Tabelle J.4-1] (akt. Norm)

Table 6:Rated load derived by testing (act. Standard)

Tab. 7:Durch Prfung ermittelte Nennlast [Tabelle J.4-1] (nderungsvorschlag)

Table 7:Rated load derived by testing (modification proposal)

Type of support

Permissible load based on

Ultimate failure load Yield load Buckling load

Rod type parts Fu/4.0 or Fu/2.4 K1 Fy/1.6 K2 Fb/1.6 K2

Clamps Fu/4.0 or F

u/2.4 K

1F

y/1.6 K

2F

b/1.6 K

2

Rigid struts orshock absorbers

Fu/4.0 or Fu/2.4 K1 Fy/4.0 or Fy/2.4 K1 Fb/2.5

Sway braces Fu/4.0 or Fu/2.4 K1 Fy/4.0 or Fy/2.4 K1 Fb/2.5

Anchor tension rods Fu/4.0 or Fu/2.4 K1 Fy/4.0 or Fy/2.4 K1 Fb/4.0 or Fb/2.4 K1

Where

Type of support

Permissible load based on

Ultimate failure Yield loadStability load,buckling load

Rigid supports

FU/ 4.0 orFU/ (2.4 K1)

FY/ (1.6 K2) FS/ 2.5Hanger clamps

Hangers

Rigid struts

FU/ 4.0 orFU/ (2.4 K1)

FY/ (1.6 K2) FB/ 2.5

Shock absorbers

Sway braces

Compression loadedpipe supports

(!!!)

Euler bucklingwithout (1/8)

with (1/8)

11


12/14

FACHBERICHTE


For components loaded in this way the fol-lowing two equations [L.5-1] and [L.5-2]must be observed:

Annex L ends with the definition of the equa-tions. The user must have wide experienceof foreign codes to recognize that with f,calculated stresses, and with F, permissi-ble stresses are meant. This nomenclaturedoes not accord with the first part of thestandard. The indices x and y denote thebending axes of the beam, x is normallythe longitudinal axis of the beam. Altogetherall the other eight symbols of the [Eq. L.5-1]are not defined, except for a.

Annex N: Documentationfor pipe supports

In Annex N the rules for the documentationof pipe supports are set out. The 2002 issuethereby makes the classifications material,design, manufacture, testing and certifica-tion for the three support classes S1 S3.The requirement are kept fairly general; forexample, for Class 3 pipe supports, all ma-terials are to be supplied with inspection cer-tificates 3.1, independently of the working/operating temperature, for example. AnnexN was revised on the basis of a Germanmodification proposal, to be formed in theEuropean agreement as EN 13480-3:2002

/ prA5:2007. In this proposal the documen-tation (inspection certificate) is itemized indetail according to the product shapes e.g.springs, welding consumables, welding fil-lers, sheet metal, connections and smallparts. The operating temperature as in VGBR 510 L, is thereby taken into account. Inthe second part of the table (design, manu-

facture, testing and certification), referenceswere included in Annex I (production testingof spring supports and shock absorbers)and Section 13 (pipe supports).

Section 11: Integralattachments

In Section 11 the stress determination forhollow circular and rectangular attachmentsis defined. Shear lugs and trunnions actuallybelong to the piping and not to the pipe sup-ports, but this interface between pipe stressanalysis and pipe support design is not freeof repercussions. The calculation method iswell known from various other codes (e.g.ASME Code Cases N-392-3 and N-318-5[8]). The German modification proposal com-prises four points.

Proposal 1: Restructuring of the code

The Section Integral attachments shouldbe placed after the section Stress analysis,as the stress analysis output data supply theinput data for calculation of the attachments.(This was not done, at the request of theFrench delegation).

Proposal 2: Correction ofthe clerical errors

In the formulae of Chapter 11 there are anumber of clerical errors DIN EN 13480-3correction 2 also contains some mistakes.As examples, only the corrections to equati-on [11.3.5-2] are mentioned here.

Proposal 3: Rearrangementof the section

As an aid to users and for easier applicationSection 11 is to be rearranged. The calcula-tion methods for hollow circular and rectan-gular attachments are to be summarized ina single section in each case.

Proposal 4: Integrated attachmentsin the creep range

In the current version of the code the calcula-ted stresses for the run pipe, the attachmentand the weld seam are secured against theyield stress. For the creep range, correspon-ding stress limits are to be included.

The additional relation is included for the runpipe:

The following equation limits the stresses inthe pipe wall to the median value of the creeprange in a similar way to [Eq. 12.3.5-1].

1.25 fcrwith0.75 i 1,

MT, PT; additional stresses resulting fromdead weight, constantly acting loads andloading due to restricted thermal expansion.

A further condition limits the maximum stressin the attachment.

In the creep range, the equivalent stress isto be limited to a value smaller or equal to

the median value of the creep range: NT**1.25 fcr

One condition in each case for trunnions/shear lugs limits the resulting shear stressin the attachment or weld seam:

For trunnions in the creep range, the resul-ting shear stress is limited to the averagevalue of the shear creep strength dep.on time according to the von-Mises hypo-thesis:

For rectangular attachments in the creeprange the resulting shear stress is limitedto the average value of the shear creepstrength dep. on time according to thevon-Mises hypothesis:

Section 12: Flexibility analysisand acceptance criteria(12.2.8 Support conditions)

In Section 12.2.8 the support or boundaryconditions are defined for the pipe systemcalculations. In the German translation, unfor-tunately, the usual terms are not used. Twoexamples will serve to show how readerswho occupy themselves largely with pipesystem calculations can be left in some con-fusion. In the current issue of the standardthe following definitions are to be found:

Typische Absttzungen sind: Halterun-gen: Absttzungen, die Krften und Mo-menten in allen Richtungen standhalten, z.B. Verankerungen;

(Typical supports are: supports which with-stand all forces and moments in all direc-tions, e.g. anchors)

The use of common terms improves read-ability:

Typical pipe supports are: fixed points:pipe supports which absorb forces andmoments in all directions.

A further example of an unfortunate choiceof words:

Bild 13:Darstellung der Knickbieglinie - aus[Tabelle L.5-1]

Fig. 13:Picture of buckling-bending line takenfrom [Table L.5-1

and

Mn not W

J not J

12

F F

L

0.7 < K < 1


13/14

FACHBERICHTE


Absttzungen mit variabler Sttzkraft:Absttzungen, deren Fhigkeit zur Aufnahmevon Krften und Momenten in linearer Be-ziehung zu Federsteifigkeit und Verformungsteht;

(Supports with variable supporting force:supports whose capacity to absorb forcesand moments stands in linear relation to

spring rate and deformation.)

In general, spring hangers or spring sup-ports are thereby meant: rotational springsare more seldom used. The term Verfor-mung (deformation)is not a happy choiceeither, but it is the literal translation of theEnglish term deformation. A better formu-lation is:

Pipe support with variable force: Pipesupport whose capacity to absorb forcesstands in linear relation to spring stiffnessand displacement.

The further definitions in this section will alsodiffer slightly from the current version in thenext issue of the standard.

Literature

[1] Specification for Unfired fusion welded pres-sure vessels PD 5500:2003 Published by:British Standards Institution BSI, 389 Chis-wick High Road, London

[2] ASME Boiler and Pressure Vessel Code, Sec-tion III, Division 1, Subsection NB Publishedby: The American Society of Mechanical Engi-

neers, New York - USA[3] ASME B31.1-2007 Power Piping, ASME

Code for Pressure Piping Published by: TheAmerican Society of Mechanical Engineers,New York - USA

[4] CODETI Devision 1 Code de construction desTuyauteries Industrielles Published by: SNCT(Socit Nationale de Contrle Technique) -France

[5] ASME Boiler & Pressure Vessel Code, Sec-tion III Division 1 - Subsection NF: SupportsPublished by: The American Society of Me-chanical Engineers, New York USA

[6] ANSI/AISC 360-05 - An American NationalStandard: Specification for Structural SteelBuildings Published by: American Instituteof Steel Construction, INC. Chicago, Illinois -USA

[7] Rgles De Conception Et De ConstructionDes Matriels Mecaniques Des lots Nucl-aires Rep (Design And Construction Rules ForMechanical Components Of PWR Nuclear Is-lands) Published by: AFCEN France

[8] ASME Boiler & Pressure Vessel Code, Sec-tion III Division 1 Code Case N-392-3 / N-318-5Published by: The American Society of Me-chanical Engineers, New York USA

[9] Technische Regeln fr Dampfkessel (TRD),Festigkeitsberechnung von Dampfkesseln,herausgegeben vom Verband der Techni-schen berwachungs-Vereine e.V.

Technical Rules for Steam Boilers (TRD),Calculation of boiler strength, TRD 300series Design, published by Verband derTechnischen berwachungs-Vereine e.V.

[10] FDBR-Richtlinien Berechnung von Kraftwerks-rohrleitungen, Herausgegeben vom FDBRFachverband Dampfkessel-, Behlter- undRohrleitungsbau e.V., Dsseldorf

FDBR guideline Design of Power Piping,published by FDBR Fachverband Dampfkes-sel-, Behlter- und Rohrleitungsbau e.V., Ds-seldorf

[11] AD 2000-Regelwerk, herausgegeben vomVerband der TV e.V. (VdTV), Berlin, BeuthVerlag GmbH, Berlin-Wien-Zrich

AD 2000 bulletins, published by Verband der

TV e.V. (VdTV), Berlin, Beuth Verlag GmbH,Berlin-Wien-Zrich

[12] DIN V 2505, Berechnung von Flanschverbin-dungen, Vornorm Ausgabe 1/1986, BeuthVerlag GmbH, Berlin

DIN V 2505, Calculation of flanged joints,Issue 1/1986, Beuth Verlag GmbH, Berlin

[13] VGB Richtlinien Rohrhalterungen VGB R 510 L,Herausgegeben von der VGB PowerTech e.V.,Essen

VGB Guidelines Pipe Supports VGB R 510 L,published by the VGB PowerTech e.V., Essen,Germany

[14] Sicherheitstechnische Regeln des Kerntech-nischen Ausschusses (KTA); KTA 3205.3,Komponentensttzkonstruktionen mit nicht-integralen Anschlssen; Teil 3: SerienmigeStandardhalterungen, Herausgegeben vonder KTA-Geschftsstelle

Safety Standards of the Nuclear SafetyStandards Commission (KTA); KTA 3205.3,Component Support Structures with Non-Integral Connections, Part 3: Series-Production Standard Supports Published by:KTA-Geschaeftsstelle c/o BfS, Willy-Brandt-Strasse 5, D-38226 Salzgitter, Germany

Authors:

Dr.-Ing. Jochen WeberBHR Hochdruck-RohrleitungsbauGmbH, Essen

Tel. +49(0)201/3645486E-Mail: [email protected]

Dr.-Ing. Heinz-Wilhelm LangeLISEGA AG, Zeven

Tel. +49(0)4281/713-276E-Mail: [email protected]

13


14/14

The high-pressure pipe systems we develop,

fabricate and install for power stations across

the globe must be able to withstand extremepressures and temperatures of up to 700C.

A new pipe-bending machine Europes most

efficient induction DA 850 pipe-bending

system has meant technological independence

for BHR in the fabrication of all the high-pressure

pipe bends needed for water-steam circuits in

power stations.

Another key factor in meeting increasing demands is the use of sophisticated,

efficient welding techniques such as submerged-arc narrow-gap welding and

branch welding at the pre-fabrication site, TIG orbital narrow-gap welding during

installation and internal cladding in pipes for the reactor coolant line in nuclear

reactors where the company has highly specialised know-how.

www bhr bilfinger de

Power for our customers

BHR Hochdruck-Rohrleitungsbau GmbHHeadquartersWolbeckstr. 25 45329 EssenTel.: 0201 3645-0 Fax: -111i f @bh bilfi d

EN13480-3 Current Status

Documents

Transcript of EN13480-3 Current Status