Expansion Joints and Bellows

7/24/2019 Expansion Joints and Bellows

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TRAINING MANUAL PIPING

BELLOWS EXPANSION JOINT

Uhde India Limited

DOC No. : 29040-PI-UFR-0034

Rev. : R0

Page : 1

CONTENTS

Page

0.0 Cover Sheet 1

1.0 Introduction 2

2.0 Application 2

3.0 Bellow Pressure Thrust 2 3

4.0 Bellow Types 4 13

5.0 System Design Considerations 13

6.0 Internal Sleeve Requirement 13

Appendix A 14-15

App licable Rev is ion:

Prepared:

Date:

Checked:

Date:

App roved:

Date:

First Edition: R0

Prepared: DNL

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Checked: AKB

Date:

App roved:

Date:

File Name:C- 34 Server: Pune: KUMUS 207 VKO: KUMUS 209

Directory- Pune: Refer\Pi\Training Manual VKO: Refer\Training Manual


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Uhde India Limited

DOC No. : 29040-PI-UFR-0034

Rev. : R0

Page : 2

1.0 INTRODUCTION:

In a piping system a Bellow is like a sealed spring. Sealed because it is required to containthe fluid pressure which is flowing through it and spring because it is required to respond tothe movement of the connected piping without offering appreciable stiffness to the pipingsystem. A Bellow element employed in a piping system is an assembly of generally more than

one convolute in series. The convolutes are designed strong enough to withstand the internalpressure of the system, at the same time the typical contour of the convolute assembly allowsit to flex under thermal movement of the connected piping. As a result of this extremeflexibility the Bellow as such is highly incapable of absorbing any longitudinal loads by its own,thereby requiring external attachments to transfer these longitudinal loads to its connectedpiping for maintaining the overall stability of the piping system under question.

2.0 APPLICATION:

The Bellows are generally employed in a piping system in one of the following situations:

When the space constraints do not permit providing adequate flexibility by conventionalmethods (e. g. expansion loops etc.) for maintaining the system stresses withinacceptable limits.

When conventional solutions (e.g. expansion loops etc.) create unacceptable processconditions (e.g. excessive pressure drop).

When it is not practical to limit the piping induced loads on the terminal nozzles of theconnected equipment within admissible limits by conventional methods.

When the equipment such as Compressors, Turbines, Pumps etc. necessitate isolatingthe mechanical vibrations from being transmitted to the connected piping.

3.0 BELLOW PRESSURE THRUST:

The end anchors in a piping system employing a Bellow requires special considerations owing

the large imbalance axial force generated due to internal system pressure acting on the

bellow convolutes. At the same time the inherent weakness of the Bellow to transfer the

longitudinal force across its ends.

It is therefore imperative that a proper assessment of the imbalance Pressure Thrust of

the Bellow and its effects on the piping end terminals be evaluated prior to using the

Bellow on a piping system of large diameter and sizable internal pressure.

To understand the above phenomena let us consider a straight length of pipe of internal

diameter D capped at its both ends and subject to an internal pressure P (refer Fig.-1A

below). The longitudinal Pressure Force acting at each capped end is:

Pf = PD2/ 4


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DOC No. : 29040-PI-UFR-0034

Rev. : R0

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The above longitudinal force is carried in tension in the Pipe wall and the system remains

stable with the opposite and equal force acting at the capped end balancing each other. Now

let us introduce a Bellow in the middle of the above pipe section (refer Fig 1B). Since the

above Bellow does not have any appreciable longitudinal stiffness it will tend to straighten out

as shown in Fig 1C below resulting into rapture of the convolutes. It is therefore necessary to

provide end anchors (refer Fig 1D below) to counter the pressure force acting at the ends

and thereby stopping the bellow convolute from flattening. The magnitude of above force will

be combined longitudinal force acting at the Bellow inside diameter and the imbalance

pressure thrust acting on the side-wall, of the convolute.

The net Pressure Thrust to be absorbed by the End Anchors, due to incorporation of the

bellow in a straight pipe line, therefore it based on the Mean Diameter of the bellow and is

given by p Dm2/ 4 where :

Dm = Mean Diameter of the bellow

P = System internal pressure.


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Uhde India Limited

DOC No. : 29040-PI-UFR-0034

Rev. : R0

Page : 4

4.0 BELLOW TYPES:

Simple Expansion Joint.

Universal Expansion Joint. Pressure Balanced Expansion Joint.

Hinged Expansion Joint.

Gimbal Expansion Joint.

Following paragraphs illustrate the typical situations for employing the above type of Bellowsdepending upon the application and configuration of the piping profile.

SIMPLE EXPANSION JOINT:

1.0 Expansion Joint fo r absorbing axial displacement.

1.1 Single Element Bellow installed in a straight line

A typical arrangement of the above application is shown in the accompanying sketch(Figure-2) below. The Bellow is locked between the end anchors (Main Anchors) and isnormally located close to one of the above Main Anchors. The other end of the Bellow isaccompanied by First Alignment Guide G1 (as close as possible to the below) followed bySecond Alignment Guide G2 at a distance of 14 D (as per EJMA recommendation). TheSecond Alignment Guide G2 is, followed by the Intermediate Guides (located as per thenormal support span) if required as per the length of the line.

Figure-2

1.2 Single Element Bellow installed in a straight line with an off set.

A typical arrangement of the above application is shown in the accompanying sketch(Figure-3) below. The application of this type is normally not recommended and will performsatisfactory only within certain limits. The axial pressure thrust of the Bellow is transmitted tothe Main Anchor through the offset, resulting into bending moment in the piping.The remaining arrangement of the Main Anchors, First and Second Alignment Guides andrest of the Intermediate Guides remains same as that of the Bellow installed in a straight line.

Figure-3


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1.3 Double Element Bellow employing an intermediate anchor in the middle when

installed in a straight line

A typical arrangement of the above application is shown in the accompanying sketch(Figure-4) below. The arrangement is generally employed in the situations where the linearexpansion of the line is of a very large magnitude. The Bellow assembly consists of 2

elements separated by an Intermediate Anchor. Thereby absorbing the linear expansion ofthe 2 sections of the pipeline individually. It may be noted that the above Intermediate Anchorneed not be designed for the bellow axial force, which cancels out between the 2 BellowElements. The remaining arrangement of the Main Anchors, First and Second AlignmentGuides and rest of the Intermediate Guides remains same as that of the Bellow installed in astraight line.

Figure-4

1.4 Double Element Bellow employing a main anchor in the middle, installed in a

straight line at the interface of changed line size (i.e. reducer)

A typical arrangement of the above application is shown in the accompanying sketch(Figure-5) below. The arrangement is similar to that of Double Element Bellow on a straightpipeline except that the middle anchor between the 2 Bellow Elements is required to be

designed as Main Anchor for the differential axial thrust of the 2 Bellows employed on eachside of the Reducer.

Figure-5

1.5 Three Element Bellow employing a main anchor in the middle, installed at the

juncti on of the branch connecti on

A typical arrangement of the above application is shown in the accompanying sketch(Figure-6) below. The middle anchor between the 3 Bellow Elements in this case is requiredto be designed as Main Anchor for the axial thrust imposed by the Bellow of the branch pipe.


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Figure-6

2.0 Expansion Joint for absorbing lateral movement, angular rotation and combined

movement

2.1 Single Element Bellow employing a directional anchor, installed in the longer leg of

L shaped piping profile

A typical arrangement of the above application is shown in the accompanying sketch(Figure-7) below. The Bellow is located at 1 end of the longer leg and thereby absorbing thelinear expansion of the longer leg as axial displacement. The Main Anchor near the Bellow isa Directional Main Anchor (DMA), which prevents the pipe end from moving axially, at thesame time allowing the expansion of the shorter leg, which is absorbed by the Bellow as alateral deflection. The Anchor on the shorter leg is required to be designed, only asIntermediate Anchor. The remaining arrangement of the First and Second Alignment Guidesand rest of the Intermediate Guides remains similar to that of the Bellow installed in a straightline to prevent the straight pipe of the longer leg from rotating/ buckling.

Figure-7


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2.2 Single Element Bellow employing a directional anchor, installed in the shorter leg

of L shaped piping profile

A typical arrangement of the above application is shown in the accompanying sketch

(Figure-8) below. The Bellow is located in the shorter leg and thereby absorbing the linearexpansion of the longer leg as lateral displacement. The Main Anchor near the Bellow is aDirectional Main Anchor (DMA), which prevents the pipe end from moving axially, at the sametime allowing the expansion of the long leg, which is absorbed by the Bellow as a lateraldeflection. The Anchor on the longer leg is required to be designed, only as Intermediate

Anchor. Only 1 Guide is required on the longer leg for alignment purpose.

Figure-8

2.3 Single Element Bellow employing a tie rod in place of a directional anchor, installed

on the shorter leg of L shaped profi le

A typical arrangement of the above application is shown in the accompanying sketch(Figure-9) below. This is a modified arrangement wherein, by employing a tied Bellow (in theshorter leg) the need of the Directional Main Anchor (DMA) is eliminated. Owing to tie rods thebellow can only absorb lateral deflection (other than its own axial growth) and hence the axialgrowth of shorter leg must be accommodated by the flexibility in the longer leg.

Figure-9


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UNIVERSAL EXPANSION JOINT:

1.0 Bellow with tie rod installed in a Z shaped piping profi le in a single plane

A typical arrangement of the above application is shown in the accompanying sketch below(refer Figure-10). Typically the assembly employs 2 Bellow elements tied across. The abovebellow is purely lateral, and hence the axial expansion of the leg (excluding the expansion ofthe Bellow itself) housing the Bellow is, required to be accommodated by the Flexibility of theadjoining legs. To prevent the longer legs from rotating necessary Directional Guides areprovided as shown. The End Anchors are required to be designed as Intermediate Anchorsonly.

Figure-10

2.0 Bellow w ith tie rod installed in a Z shaped piping p rofil e in two plane

A typical arrangement of the above application is shown in the accompanying sketch

(refer Figure-11) below. The arrangement is completely similar to that of the earlier situationexcept that the Bellow is subject to lateral deflection in a resultant plane derived from themagnitude of the 2 linear expansion components of the longer legs.

Figure-11


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DOC No. : 29040-PI-UFR-0034

Rev. : R0

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3.0 Bellow w ith pantographic linkage

A typical arrangement of the above application is shown in the accompanying sketch(Figure-12) below. Owing to the limited space between the 2 directly connected equipment

nozzles the Bellow is required to absorb axial as well as lateral deflection. In such case theequipment nozzles must be designed to take the axial force due to Bellow imbalance area.The Pantographic linkage is provided to distribute the expansion between the 2 Bellows andcontrol their movements.

Figure 12

PRESSURE BALANCED EXPANSION JOINT

As it is evident from the forgoing discussion the axial thrust imposed by the imbalance area ofthe Bellow under internal pressure is a main concern in designing the Piping Systememploying such Bellows. The conventional method of designing such systems is by employingMain Anchors to absorb the above axial force. It is however not always practical (due tospace/ access constraints) to achieve these conventional solutions. The excessive magnitudeof the axial force could also become prohibitive in some instances. The Pressure BalanceBellow design, which basically is a combination of a Flow Bellow and a Balancing Bellow,comes handy in addressing many of such situations.

The working principle of the above Bellow relies on the fact that since both Flow andBalancing Bellow have identical cross sectional area, they will produce equal, but opposite indirection, forces under the same internal pressure. If the ends of these Bellows are locked toeach other by a suitably designed tie-rod, the above equal and opposite forces will cancel outto transmit no axial force on the end terminals of the connected piping. At the same time the

above tie rod will not interfere with the Flow Bellow in absorbing axial/ lateral deflections.

1.0 Single Element Bellow installed at the 90Oturning of a piping profile

The sketches below show a typical arrangement of 3 such applications (refer Figure-13,Figure-14 and Figure-15 below. In all the 3 cases the Bellow is capable of absorbing primarilyaxial movement along with a small amount of lateral movement. Since the axial thrust due tointernal pressure is cancelled out between the two Bellows the system requires onlyIntermediate Anchors wherever applicable.


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Figure-13

Figure-14

Figure-15


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2.0 In-line Pressure Balanced Bellow

A typical arrangement of the above application is shown in the accompanying sketch(Figure-16) below. The above arrangement is typically employed in the situations where the

bellow is required to be, installed on a long line without the possibility of installing the MainAnchors. The common balancing Bellow effectively nullifies the imbalance axial force of the 2flow Bellows, at the same it allows the required deflection to be absorbed within the assembly.The piping end anchors are, therefore required to be designed as intermediate anchors only.

Figure 16

3.0 Double Element Bellow installed at the 90Oturning of a piping profile for absorbing

large lateral movements

A typical arrangement of the above application is shown in the accompanying sketch Fig.17below. Where large amount of lateral deflections, are involved a Pressure Balanced UniversalJoint (with tie rod) may best suit to the situation. By a proper design of the tie rods to rotatearound its attachment points it is possible to absorb the lateral deflection by the combination

of 2 flow bellows where as the balancing bellow is subject to only axial deflection.

Figure 17

HINGED EXPANSION JOINT

Hinged expansion joints are usually used in sets of 2 or 3 elements to absorb lateraldeflection in one or more directions in a single plane. Each element of the assembly is subjectto pure angular rotation by its hinge pin. Each pair of bellow element connected by a segmentof pipe will act in unison to absorb lateral deflection in much the same way as universal joint ina single plane. The hinges are designed strong enough to take the axial pressure thrust andalso to transmit the piping deflections in a plane perpendicular to the plane of hinge rotation.The magnitude of the lateral deflection that could be absorbed by a hinged bellow is directlyproportional to the length of spool piece connecting the bellow elements.


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DOC No. : 29040-PI-UFR-0034

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1.0 Two Element Bellow

A typical arrangement of the above application is shown in the accompanying sketch(Figure-18) below. Since the axial pressure thrust is absorbed by the hinges the piping endanchors need to be designed as intermediate anchors only. The position of the pipe guides on

the axial pipes should provide adequate flexibility to absorb the expansion of the offset leghousing the bellow.

Figure-18

2.0 Three Element Bellow

A typical arrangement of the above application is shown in the accompanying sketch(Figure-19) below. The above arrangement is typically employed in the situations where the

flexibility in Z shaped profile (in a single plane) is not sufficient to absorb the thermalexpansion of the offset leg.

Figure-19


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GIMBAL EXPANSION JOINT

A typical arrangement of the above application is shown in the accompanying sketch(Figure-20) below. Just as hinged expansion joints offer a great capacity to absorb lateralexpansion in a single plane, the Gimbal Expansion Joints offer the same feature in a multiple

plane system. Generally the ability of Gimble Joint to absorb the lateral movement in anyplane is best utilized by employing 2 of such bellows connected together by a pipe spool. Thestructure of the Gimble ic adequately designed to absorb the axial pressure thrust and hencethe piping end Anchors need to be designed as Intermediate Anchors only. Similar to hinged

joint the growth of the offset leg accomodating the bellows must be absorbed by the adjoiningpiping legs.

Figure-20

5.0 SYSTEM DESIGN CONSIDERATIONS:

The design of the piping system employing a Bellow shall take into account therecommendations made by EJMA Standard. The main consideration while employing abellow is a piping system are covered in Doc.No.29040-PI-UFR-0027 of the Piping TrainingManual.

The specification for the Bellow shall as a minimum provide technical information as perSpecification Sheet given as Appendix-A of EJMA. The same is enclosed as attachmentto this chapter.

6.0 INTERNAL SLEEVE REQUIREMENT:

Internal sleeves are recommended when it is necessary to reduce the system pressure dropto minimum. The internal sleeves are also required to be provided when flow velocity in thepiping system tend to approach the resonant velocity for the Bellow. standards providesnecessary guide lines when evaluating the sleeve requirement for the Bellow in view of itsresonant velocity.


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DOC No. : 29040-PI-UFR-0034

Rev. : R0

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APPENDIX A

STANDARD EXPANSION JOINT SPECIFICATION SHEETCompany : Date : / / /

Sheet ofProject : Inquiry No.

Job No.Item No.EJ Tag No.

1. Quantity2. Nominal Size / I.D./O.D. (In.)

3. Expansion Joint Type

4a Fluid Information Medium Gas /Liquid4b Velocity(Ft./Sec.)

4c Flow Direction

5. Design Pressure, psig.

6. Test Pressure, psig.7a Temperature Design (F)

7b Max./Min. (F)

7c Installation (F)8a Maximum Installation Movement Axial Compression (in.)

8b Axial Extension (in.)

8c Lateral (in.)8d Angular (deg.)

9a Maximum Design Movements Axial Compression (in.)

9b Axial Extension (in.)

9c Lateral (in.)9d Angular (deg.)

9c No. of Cycles

10a Operating Fluctuations Axial Compression (in.)10b Axial Extension (in.)

10c Lateral (in.)

10d Angular (deg.)10c No. of Cycles

11a Material of Construction Bellows

11b Liners

11c Cover 11d Pipe Specification

11e Flange Specification

12. Rods (Tie/Limit/Control)13 Pantographic Linkage

14 Anchor Base (Main/Intermediate)

15a Dimensional Limitations Overall Length (in.)

15b Outside Diameter (in.)15c Inside Diameter(in.)

16a Spring Rate Limitations Axial (lbs./in.)

16b Lateral (lbs./in.)16c Angular (lbs./in./deg.)

17 Installation Position Horiz./Vert.

18a

18b

Quality Assurance Requirements Bellows

Weld NDE

Long.Seam

Attach.

18c Pipe NDE18d Design Code Reqrd.

18e Partial Data Reqrd.

18f

18g19 Vibration Amplitude / Frequency

Cont'd/-


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APPENDIX A

STANDARD EXPANSION JOINT SPECIFICATION SHEETCompany : Date : / / /

Sheet of

Project : Inquiry No.

Job No.Item No.EJ Tag No.20 Purge.Instrumentation

Connection

21a Facing

21b O.D.(in.)

21c I.D.(in.)21d Thickness (in.)

21e B.C.Diameter (in.)

21f No. Holes21g Size Holes

21h Hole Orientation

SpecialFlangeDesign

Piping Sketch :

Expansion Joints and Bellows

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