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2013 International Nuclear Atlantic Conference - INAC 2013Recife, PE, Brazil, November 24-29, 2013ASSOCIAÇÃO BRASILEIRA DE ENERGIA NUCLEAR - ABENISBN: 978-85-99141-05-2COMPARATIVE STUDY OF DESIGN OF PIPING SUPPORTS CLASS 1,2 AND 3 CONSIDERING GERMAN CODE KTA AND ASME III – NF.Altair A. Faloppa1, Gerson Fainer1, Marcos V. Elias2 and Miguel Mattar Neto11Instituto de Pesquisas Energéticas e Nucleares (IPEN / CNEN – SP)Av. Professor Lineu Prestes, 224205508-000, São Paulo, SP, [email protected]; [email protected]; [email protected]ás Termonuclear S.A. - ELETRONUCLEARDepartamento GTP – TRua da Candelária, 65 Centro – 5º andar20091-906. Rio de Janeiro, RJ, [email protected];ABSTRACTThe objective of this paper is developing a comparative study of the design criteria for class 1, 2, 3 pipingsupports considering the American Code ASME Section III – NF and the German Code KTA 3205.1 to thePrimary Circuit, KTA 3205.2 to the others systems and KTA 3205.3 series-production standards supports of aPWR nuclear power plant. An additional purpose of the paper is a general analysis of the main design conceptsof the American Code ASME Boiler and Pressure Vessel Code, Section III, Division 1 and German NuclearDesign Code KTA that was performed in order to aid the comparative study proposed. The relevance of thisstudy is to show the differences between codes ASME and KTA since they were applied in the design of theNuclear Power Plants Angra 1 and Angra 2, and to the design of Angra 3, which is at the moment underconstruction. It is also considered their use in the design of nuclear installations such as RMB – ReatorMultiPropósito Brasileiro and LABGENE – Laboratório de Geração Nucleoelétrica.1. INTRODUCTIONThe objective of this paper is developing a comparative study of design criteria for class 1, 2,3 piping supports considering the American Code ASME code Section III – NF and theGerman Codes KTA 3205.1 to the Primary Circuit, KTA 3205.2 to the others systems andKTA 3205.3 series-production standard supports of a nuclear power plant. The papercompares the prescriptions of “Design by Analysis” and “Design by Rule” from ASME, with“Analysis of the Mechanical Behavior” and “Component Specific Analysis of the MechanicalBehavior” from KTA, and also compares the equations for piping design of both codes.A general description of the German KTA standards is presented in [1]. Also the differencesbetween ASME standards [2]-[8] and KTA standards [9]-[20] are analyzed in [21]. Thecomparison between KTA 3201.2 and ASME NB standards applied to the Primary Circuitdesign is summarized in [22] and included in section 3 of the paper. The main aspects of thepiping support design were discussed in section 4 and an example of a piping supporthardware calculation was presented in section 5. Some comments and conclusions areaddressed in section 6.

2. TSSmSTSTRTSySyRysosnSuTtmy additional thickness to account for material corrosion (ASME)Absolute value of the minus tolerance of wall thickness (KTA)value accounting for wall thickness reduction due to mechanical wear (KTA)Coefficient of frictionoutside diameter of pipe (ASME)outside diameter of pipe (KTA)Young modulusallowable stress (bending)Moment of inertiaNormal forceSpan of supportsdesign pressure (ASME and KTA)minimum tensile strength at room temperature (KTA)minimum tensile strength above room temperature (KTA)minimum yield strength at room temperature (KTA)minimum yield strength above room temperature (KTA)room temperature (ASME and KTA)allowable stress (ASME class 2 and class 3)allowable stress (ASME and KTA)minimum tensile strength at room temperature (ASME)minimum tensile strength above room temperature (ASME)minimum yield strength at room temperature (ASME)minimum yield strength above room temperature (ASME)calculated wall thickness (KTA)nominal wall thickness (KTA)ultimate tensile strengthtemperatureminimum required wall thickness (ASME)parameter to adjust the Boardman equation to the Lamé equation (ASME)Poisson s ratioThermal expansion coefficient3. ASME SECTION III VERSUS KTA3.1. GeneralThe American Society of Mechanical Engineers (ASME) is a professional membershiporganization with experts in all areas of mechanical engineering. The ASME committeesissue codes and standards focusing mechanical engineering providing rules andrecommendations to apply in the design, fabrication, installation and inspection of pressurevessels, pumps, valves, piping and supports.The organization of the ASME code for instance, ASME Section III division 1 that definesrules to build a nuclear power plant components, presents the division in Subsections, andeach Subsection is organized in Articles, as shown in Table 1.INAC 2013, Recife, PE, Brazil.

Table 1: ASME III organizationDIVISION 1ARTICLESSubsection NB - Class 1 ComponentsSubsection NC - Class 2 ComponentsSubsection ND - Class 3 ComponentsSubsection NE - Class MC ComponentsSubsection NF - Supports/2//3//4//5//6/1000 - Introduction or Scope2000 - Material3000 - Design4000 - Fabrication and Installation5000 - Examination6000 - Testing7000 - Overpressure Protection8000 - Nameplates, StampingThe Nuclear Safety Standards Commission (KTA) has the task to issue nuclear safetystandards to the design of German nuclear power plants components. KTA design rules werederived from ASME code, while adding some design rules from German industry experience.There are 92 KTA standards [21] to cover protection, transportation and safe operation ofnuclear power plants. Concerning the mechanical design, there are 9 safety standards: KTA3101.3 [10], KTA 3201.2 [11], KTA 3204 [12], KTA 3205.1 [13], KTA 3205.2 [14], KTA 3205.3[15], KTA 3211.2 [16]-[17], KTA 3401.2 [18], KTA 3902 [19] and KTA 3905 [20].The design concepts of KTA standards are applied to the systems of the plant. For instance,the KTA 3201.2 provides design rules for pressure and activity retaining boundaries ofcomponents and piping systems of the primary circuits, while KTA 3211.2 provides designrules for the others systems. KTA standards apply, also, for specific systems of power plantsand contain rules and regulations for subjects like material or in-service inspection. A typicalKTA division of subjects is presented in Table 2, although not all KTA Standards areorganized in this manner.Table 2: KTA 3201 and 3211 organizationKTA 3201 (3211)Volume32xx.1 - Details material32xx.2 - Outlines design andanalysis32xx.3 - Contains rules formanufacturing32xx.4 - Covers in-service inspectionand operational monitoringINAC 2013, Recife, PE, Brazil.Sections1. Scope2. General principles3. Load case classes as well as design, service and testloadings and limits4. Effects on the components due to mechanical and thermalloadings, corrosion, erosion and irradiation5. Design6. Dimensioning7. Analysis of mechanical behavior8. Component-specific analysis of mechanical behavior9. Type and extend of verification strength and pertinentdocuments to be submittedAnnexes

The main difference between ASME and KTA is that the German code deals with the systemof the plants, and the American code has a broader scope and is not restricted to a systems ortypes of power plants. The equivalence between KTA design standards and ASME SectionIII, Division 1 Subsections can be established as given in Table 3.Table 3: ASME versus KTA equivalenceASME Section III, Div. 1 KTA StandardSubsectionsNB (Class 1 Components)NC (Class 2 Components)ND (Class 3 Components)NE (Class MC Components)NF (Supports)KTA 3201.2 and KTA 3211.2KTA 3211.2KTA 3211.2KTA 3401.2Primary System:KTA 3201.2 Sections 5.3.6 and 8.5 for integral areas ofcomponent support structuresKTA 3205.1 for non-integral areasOther than Primary System:KTA 3211.2 Sections 5.3.6 and 8.5 for integral areas ofcomponent support structuresKTA 3205.2 for non-integral areasKTA 3205.3 for standard supports3.2. Design PressureThe ASME and KTA codes apply the concept that the wall thickness of a straight pipecalculated with design pressure determines which pipe schedule is needed. The componentsand fittings have to be specified according to the pipe schedule. This is because the burstpressure of a tested product is greater than that of a straight pipe of the same schedule.ASME code outlines for design pressure of piping in NB-3132, NC-3132 and ND-3132, theequation for calculating the required wall thickness of a straight pipe, as:tm PDo A2( Sm Py )(1)The allowable stress Sm for Class 1 has to be replaced by S in the equation (1) for Class 2 &3. When the factor y is 0.4, the equation (1) is called Boardman equation, and is anapproximation of the Lamé equation, which calculates the elastic hoop stress of a thickwalled cylinder under internal pressure.KTA formula for design pressure of straight pipes is:so da P2 Sm P(2)As in ASME code, the allowable stress Sm for Class 1 must be replaced by S in the equation(2) for Class 2 & 3.INAC 2013, Recife, PE, Brazil.

The nominal wall thickness sn is then calculated by:sn so c1 c2(3)The calculated minimum wall thickness with equation (1), ASME code, and equation (3),KTA standard considering c1 as the minimum value of the minus tolerance, are nearlyidentical, differing by less than 1%.3.3. Design by AnalysisDesign rules for Design by Analysis are defined in NB-3200 and NC-3200, for class 1 andclass 2 components respectively. There is no Subsection ND-3200, so, a general analysis canonly be performed with NB and NC. Design basis of ASME is described in NCA-2140.In order to develop a specific component design, it is required that all loadings applied to theplant conditions are already defined to be considered in it. The design condition, the servicelevels and its correlation to the plant condition (normal, upset, emergency and faulted) andtest loadings are defined in ASME and KTA as showed in Table 4.Table 4: Service loadings - ASME and KTAPLANT CONDITIONSDesignService Level ALevel BLevel CLevel DTestLevel Pnormal operationabnormal operationemergencyfaulted conditionstest e structural integrity for design, service and test loadings has to be proved. The stressintensity Sm (class 1) and S (class 2 & 3) have to be used to calculate the design, service andtest limits with one of the analysis methods listed bellow:1.2.3.4.5.elastic analysislimit analysiscollapse load analysisplastic analysisshakedown analysisThe theory of failure for combining stress, stress intensity or equivalent stress, is the so calledTresca s maximum shear stress theory and is used as proof of structural integrity to bothcodes ASME and KTA.Design rules for “General Analysis of the Mechanical Behavior” are defined in Section 7 ofKTA 3201.2 for Primary Circuit components and KTA 3211.2 for component of the otherssystems. The section 7.7 “Stress Analysis” provides the design rules, which are the same asINAC 2013, Recife, PE, Brazil.

ASME code. It means that the design, service and test conditions and the analysis methodsare the same as defined in the earlier paragraph.3.4. Design by RuleDesign rules for component specific analysis, class 1 & 3, of ASME are defined inSubsection NB, NC and ND 3300-3600. For class 2 pressure vessels, ASME providesalternative design rules in NC-3200, in addition to those of NC-3300. In the KTA standards,KTA 3201.2 and KTA 3211.2, the design rules are defined in Sec. 8.2, Sec. 8.3, Sec. 8.4 andSec. 8.5.The design criteria for a specific component in ASME and KTA are quite the same.The Table 5 gives a resume of paragraph and/or sections that have to be applied in the designbased on ASME and KTA.Table 5: ASME versus KTA equivalenceComponentVesselPumpsValvesPipingCLASS 1NBKTA 3201.2NB-3300NB-3400NB-3500NB-3600Sec. 8.2Sec. 8.3Sec. 8.4NCNB-3200NB-3400NB-3500NB-3600CLASS 2 & 3NDKTA 3211.2NB-3300NB-3400NB-3500NB-3600Sec. 8.2Sec. 8.3Sec. 8.4Sec. 8.53.5. MaterialsASME Section II provides all information for the design analysis regarding materialsproperties. The criteria to calculate Sm, for class 1 design, are in the TABLE 1-100 ofMandatory Appendix 1 (criteria for establishing allowable stress values for tables 1A and 1B)and to calculate S, for class 2 & 3 design, are in the TABLE 2-100(a) of MandatoryAppendix 2 (criteria for establishing allowable stress values for tables 2A and 2B) of ASMESection II, Part D [8]. The tables 1A/2A/1B/2B show the values of allowable stress even inhigh temperature. It is because ASME code takes into account the effects of the creep rate todetermine the allowable stresses.KTA does not have a general section dedicated to materials like ASME Section II. Theregulations are not the same in the different KTA standards. For example, in KTA 3211.2, forclass 1, 2 & 3 outside Primary Circuit design, the materials which are permitted are listed inKTA 3211.1. In the case of KTA 3201.2, standard for class 1 Primary Circuit design, theallowable materials are listed in KTA 3201.1. The stress intensities allowable Sm for class 1and S for class 2 &3 are calculated with TABLE 6.6-1 of KTA 3211.2 based on the materialproperties, which are provided in Annex A of KTA 3211.1. KTA limits the designtemperature to 400 ºC because the effects of the creep rate, but there are materials that areallowed to be used at higher temperature.INAC 2013, Recife, PE, Brazil.

The safety factor of ASME and KTA are different for class 2 & 3. KTA S-value divides thetensile strength by 4.0 and the ASME by 3.5, as shown at the Table 6. So, the safety marginsfor tensile strength are 14% higher in KTA, while for yield strength is 7% higher than thoseof ASME. Therefore, KTA is slightly conservative compared to ASME. For class 1components, the safety margins are similar.The allowable stresses are chosen as the minimum values considering the conditions at RoomTemperature and Above Room Temperature as shown in the Table 6.Table 6: ASME versus KTA – allowable stressesStrengthTensileST/3.0CLASS 1CLASS 2 & 3KTA 3211.2ASMEKTA 3211.2ferritic austenitic (NC & ND) RT/4.0above RT 1.1STRT /3.0 RmT/2.7RmT/2.71.1STRT /3.5--Rp0.2RT/1.52/3 SyRp0.2RT/1.6Rp0.2RT/1.62/3 SyRy or0.9 SyRyRp0.2T/1.6Rp0.2T/1.1 orRp0.2T/1.5at RTat RTYieldASME(NB)2/3 Sy-above RT 2/3 SyRy or Rp0.2T/1.5 Rp0.2T/1.1 or0.9 SyRyRp0.2T/1.54. PIPING SUPPORT DESIGN ACCORDING TO ASME & KTAThe structural integrity of a piping system is ensured by providing minimum piping wallthickness (controlling the hoop stress) and an adequate design of supports for holding thepipe in place (controlling the longitudinal stress). In a mathematical model to perform thestress analysis of a piping system every point is associated with six degrees of freedom(DOF): three translations and three rotations. Without restriction, the pipe can move androtate in the x, y and z directions, but if the movement is not allowed, loads will arise in therestricted directions.Piping Support is a generic designation used to describe an assembly of structural elements,which restrict one or more degrees of freedom of the piping system, resulting in loads that aretransmitted to the building structure. By this approach, the type and function of the pipingsupport are established and summarized in the Table 7.A non-rigid piping support is a non linear type of support that restrains the movement in thedownward direction and is applied to sustain the piping weight and the loads acting in thesame direction. A dynamic support is a type of support that restrains only dynamic loads dueto earthquakes, water hammer, relief valve discharge, etc.Piping support can be built with several structural configurations, usually named “PipingSupport Hardware”, which depends on the: function of the support; distance between the pipe and building structure; available space in order to arrange the structural elements of the piping support.INAC 2013, Recife, PE, Brazil.

Table 7: Types of supports versus restricted DOF versus FunctionRestrictedDOFTYPEFunction / Devices1rigidnon-rigiddynamichanger, restraint, strut, guide and stopvariable spring, constant springsnubber2rigid(hanger or restraint or strut) guidedouble guidedynamic(hanger or restraint or strut) guide stopdouble guide stopviscodamperrigidanchor (fixed point)rigid36A piping support hardware is an assembly of mechanical parts such as beams, columns,brace, connectors, pins, bolts, nuts and are designed taking into account the conditionsdescribed in the previous paragraph and is connected to the building structure.Typical piping supports hardware arrangements usually applied in nuclear power plantsdesigned by ASME or KTA code are showed in the Fig. 1 and Fig. 2.4.1. Jurisdictional BoundaryThe jurisdictional boundaries between pipe x pipe support hardware and pipe supporthardware x building structures are treated in a similar way according to ASME and KTAcode. These are shown in Fig. 1 and Fig. 2 and summarized in Table 8:Table 8: Definition of jurisdictional boundaryBoundaryASMEKTAPipexSupportNF-1130 and requirementsof NB-1132, NC-1132 orND-1132 for piping class 1,2 or 3KTA 3201.2 section 8.5.1.2 and KTA3211.2 item 8.6.2 for non-integral areas of asupport applied to primary system andothers systemsSupportxBuilding StructureNF-1130 and requirements KTA 3201.2 item 8.5.1.2 and KTA 3211.2of concrete or metallic item 8.6.2 for non-integral areas of asupport and requirements of concrete orbuilding structuremetallic building structureIntegral area of a support is that part rigidly connected to the pipe. A lug, for instance, is anintegral area of the support and has to be analyzed with the pipe.INAC 2013, Recife, PE, Brazil.

Figure 1: Jurisdictional boundary versus function – one-directional typeNF (or KTA)Buildingstructure(steel.)pipe in accordance withNB/NC/ND (or KTA)Connection in accordance with NF (or KTA)Surface baseplate, bolts, nuts and concreteanchors shall be building structureBuilding structure(concrete)Figure 2: Jurisdictional boundary versus function - two-directional type4.2. Support DesignThe mechanical design of any structure, for instance a support, in a Nuclear Power Plant,performed with ASME or KTA, establishes procedures and rules meeting the safety of theplant. It means that “the safety criteria”, i.e., the Component Stability, the Structural Integrityand the Functional Capability, are established as defense in depth by ASME and KTA.The ASME III NF-1200 classifies the supports taking into account the function, the type ofstructure to be supported and the feasibility of series productions, like: plate and shell type supports – a support such as a skirt or saddle fabricated from plateand shell elements and normally applied in components; linear type support – a support acting only in one degree of freedom, such as tensionand compression struts, beams and columns subjected to bending, trusses, frames, archesand cables; standard supports – supports described in MSS-SP-58 [23], which was developed andapproved by Manufactures Standardization Society of the Valve and Fittings industry,and some of them is listed :o rigid supports consisting of anchors, guides, restraints, rolling or slidingsupports and rod-type hangers;INAC 2013, Recife, PE, Brazil.

ooooconstant and variable type spring hangers;snubbers;sway braces and vibration dampeners;structural attachments such as ears, shoes, lugs, rings, clamps, slings, strapsand clevises.A stress analysis of supports, according to NCA-3550 [2] and NF-3133, including theirmechanical parts, has to be performed as well as KTA establishes the proof of integrity bycalculation, considering the design of supports according to the system they belong. Thedesign of a piping support is performed in both ASME NF and KTA with one of the threedesign procedures: Design by Analysis, Experimental Stress Analysis or Load Rating. Pipingsupport hardware arrangement to support a safety class 1 piping system must attend therequirements of NF-3320 and in case of number of cyclic loading 20.000, a fatigueanalysis, as described in NF-3330, must be performed. The KTA code demands also a fatigueanalysis as shown in Table 9.Table 9: KTA code: stress analysis versus fatigue analysisPrimary CircuitKTA-3205.1Others systemsKTA-3205.2Standard supportsKTA-3205.3Stress analysisFatigue analysisStress analysisFatigue analysisStress analysisFatigue analysisSection 5(e)Section 7.3.7Section 5.1(a)Section 5.1(4)Section 3.3 (l) & 5.2Section 5.1The fatigue analysis of a piping support is performed applying the transients of level A and Bwith the procedure of NF-3330 and the transients of loading level H and HZ of KTA, and it isthe same procedure applied to analyze a piping system. The methods to perform the fatigueanalysis in both codes are “elastic fatigue analysis” and “simplified elastic plastic fatigueanalysis”. In KTA 3201.2, section 7.8.3 and 7.8.4, the two methods are described.4.3. Support and Piping DesignThe external area of the piping and the support structure hardware at the restrained pointtouch each other and, because of this, any aspects of the direct contact between surfaces anddesign parameters of piping and supports structure has to be analyzed. This way, in astructural viewpoint, we outline the most relevant parameters, such as stiffness, frictionforces, gap and localized pipe stress of the design applied to the contact surface betweenpiping and supports.4.3.1. StiffnessNormally, a stress analysis of a pipeline is performed and the resulting loads on piperestrictions are forwarded to a team which develops a support design. This independentbehavior between a piping design and support design is grounded in the assumption that thesupport has a quasi rigid behavior.INAC 2013, Recife, PE, Brazil.

According to WRC-353 [24], this decoupling is valid since: EIL3maximum deflection of 1.6 mm in the direction of load, for combining loads in theabnormal operation service (Level B).piping support hardware stiffness in the direction of load: K sup 2004.3.2. Friction forcesFrictions forces are generated by the movement of the piping system, between the pipe andany piping support hardware, during heat up and cool down of the plant operation, in theunrestrained directions. It is recommended to include theses forces in support design, in thecombination deadweight and thermal loading.The friction forces are computed as:F friction C N4.3.3. GapsThe definition of the gaps is important to improve the distribution of the loads of the contactarea and avoid stress concentration at any point at the contact area between pipe and support.A total gap recommended to a frame type support design in the cold conditions is 3.2 mm inthe direction of load. For supports located near rotating equipment nozzle or for supports type“stop” near to “relief valves” the gap is limited to 1.6 mm. Gaps recommended by [24]. Thisprescribed gap must be enough to assure that the pipe hot conditions allow free radialexpansion of the pipe.4.3.4. Localized pipe stressAny piping attachment to transmit load or restrict motion may cause, in most case, somedegree of localized stress in the pipe wall. As a general rule, clamps, U-bolts and bearing onstructural members produce stresses in the pipe and they are classified as secondary stressesin nature and, according to WRC-353 [24], can be neglected. Others type of support whichfunction is, for instance, to restrain an axial movement or to impose an anchor in the middleof a straight pipe, produces primary stresses. A special care must be taken when applyingclamps and U-bolts in thin-walled piping (Schedule 10) because an excessive installationtorque may cause high localized stresses and excessive deformation.4.4. Loads Combinations and LimitsThe “Service Limit” and “Loading Level” combination, defined in ASME and KTArespectively, are the way that these codes correlate the loads and combinations with theoperational conditions of the plant. The Table 10 shows the relationship among the “ServiceLimit”, “Loading Level” and the design criteria usually inherent at the design of a nuclearpower plant.INAC 2013, Recife, PE, Brazil.

Table 10: Service limit versus loading level x design criteriaServiceLimitA/BCLoadingLevelH / HZHS1DHS2/HS3Design CriteriaFully suitable for intended useFulfillment of stability requirements and maintenance ofrequired functions, limited deformation, generally re-usableGross plastic deformation permitted, re-use not intendedThe combinations of the loads, according to ASME and KTA codes, describing the load casesthat normally arise in the design of a nuclear power plant, are shown in Table 11.Table 11: Service limit (ASME) versus loading level (KTA)Service LimitLoadingLevelNormal (A)HUpset (B)HZEmergency (C)HS1Faulted (D)Loads combinationOBSDeadweightDeadweight thermalNormal relief valve dischargeNormal earthquake (OBE) relief valve dischargeNormal earthquake (DBE*1) relief valve dischargeNormal water hammerNormal earthquake (SSE) relief valve dischargeNormal earthquake (DBE*1) relief valve dischargeHS2/HS3 Normal earthquake (SSE) pipe ruptureNF & KTANF & KTANFKTANF & KTANFKTANF & KTA*1) – KTA 2201.4 [9]The allowable stress for normal, shear, bending, combined and equivalent stresses to NFlinear type supports class 1, 2 and 3, as well as KTA supports are summarized in Table 12.Table 12: Allowable stresses for linear type support design – ASME & KTASTRESSNormal (tension)ShearBendingBearingCombinedEquivalentINAC 2013, Recife, PE, Brazil.ASME-NFKTA0.60 Sy0.40 Sy0.66 Sy0.90 Sy0.66 Sy0.38 Sy0.66 Sy1.17 Syfa fbyfbz 1.0Ft Fby Fbz--22 normal 3 x shear 0.77 Sy

The applied service limits (A, B, C and D) and loading levels (H, HZ and HS) are defined asa function of allowable stress, Table NF-3623(b)-1, NF-3225-1 and appendix F-1334 forASME-NF, and section 7.2.7.1 and 7.2.5 of KTA 3205.1. The Table 13 shows all these limitsfor a linear type support.Table 13: Factors to the limits for linear type supportsSTRESSDesignNormal (tension)ShearBendingEquivalent1.01.01.0-ASME - NFLevel ALevel B1.01.01.0-1.33 *1)1.33 *2)1.33-Level D *3)HKTAHZ HS1.86 *4)1.86 ) - not exceed (1,5*Sh); *2) – not exceed (0,3*Sy, Sy from weld material) or (0,42*Su, Su frombase material); *3) - as item F-1334.4(a) from appendix F, adjust factor "K" for: fragile orductile steel *4) - not exceed [1,2*Sy] and [0,7*Su]; *5) - not exceed [0,72*Sy] and [0,42*Su]The allowable stress for an elastic fatigue analysis of a piping support is defined by KTA3201.2 as 3 x Sm. The ASME code outlines in NF-3330 the procedure to define the allowablestresses, as showed in Table 14.Table 14: ASME procedure to define allowable stressesLoading conditionGeometryStress categoryAllowable stressesTable NF-3332.2-1Figure NF-3332.3-1Table NF-3332.3-1Table NF-3332.2-15. EXAMPLEThe purpose of this section of the paper is to present a structural analysis of a piping supportaccording to the rules of NF and KTA in order to point out the differences between the codes.Fig. 3 shows the three dimensional and the side view of a typical piping support hardware,which provides supporting to a class 2 DN80 piping system.INAC 2013, Recife, PE, Brazil.

Figure 3: Typical piping support hardwareThe main dimensions are shown in Fig. 3. Materials properties of piping support structureused in both codes are presented in Table 15:Table 15: Materials properties – ASME x KTAMaterialCodeT(ºC) SA36 ASME 150 0,3Rst37.2 KTA 145 0,3 (mm/mºC)E1,2 E-051,2 E-05195000205800Su(MPa)SySh400340250235114-Table 16 shows load cases and typical values to piping stress analysis. The same value ofOBE load case from ASME code was adopted to load case DBE in KTA.Table 16: Loads – ASME x KTALoad caseDead Weight (W)Thermal Expansion (T)Operational Basis Earthquake (OBE)Design Basis Earthquake (DBE)Shutdown Safety Earthquake (SSE)INAC 2013, Recife, PE, Brazil.Fx(N)104185 35 55ASMEFy(N)2280 20 30Fz(N)-Fx(N)104185 35 55KTAFy(N)2280 20 30Fz(N)-

5.1. Structural ModelThe stress analysis of the piping support hardware shown in Fig. 3 is performed developing astructural model of the support with the finite element computer software ANSYS [25]. Thefinite element “SOLID95” was used to model the support geometry, resulting in twenty nodeswith three degree of freedom by node (displacements: Ux, Uy and Uz). The generated meshof the structural model can be seen in Fig. 4.AnchorPlateFigure 4: Piping support hardware – finite element meshThe displacements in directions X, Y and Z were restricted in the anchor plate that connectsthe piping support hardware to the building structure in order to represent the restrainingboundary conditions. Loads resulting from the load cases combinations in the connection ofthe piping support hardware with the pipe were applied, according to the Table 17. Thevalues of the forces in direction Z are calculated as: Fz 0.3Fx 2 Fy 2 .Table 17: Load combinations– ASME & KTAServiceLevelDesign / Level ALevel BLevel CLevel DLoad casecombinationW / W TW OBE : W T OBEW SSE : W T DBEW SSE / W T SSEFx (N)max.min.2891043246934449Fy (N)max.min.2822302-18312-28Fz (N)max.min.121133139-Once the structural model is built, the boundary conditions and the load cases are defined,then a numerical simulation with the computer program ANSYS can be performed.INAC 2013, Recife, PE, Brazil.

5.2. ResultsThe results of the computational simulation to normal, bending, shear, combined, equivalentstresses and the stress limits of the used material steel SA-36 (NF) and Rst 37.2 (KTA) aresummarized in Table 18.Table 18: Stress results and combinations – ASME & KTA (MPa)NF(KTA)NormalBendingShearCombined / el .2226.8 1.0180,0

The design concepts of KTA standards are applied to the systems of the plant. For instance, the KTA 3201.2 provides design rules for pressure and activity retaining boundaries of components and piping systems of the primary circuits, while KTA 3211.2 provides design rules for the others systems.