Expansion Jointby

Nivedit Mathur & Manik DeshpandeNISH-IN MLD-IN

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This presentation consists of:- Introduction. Definition and Application. Working Principle. Metallic versus Non-Metallic types. General considerations for calculating expansion values. Case wise methodology:- I – For Straight Duct. II – For Inclined Duct. III – For Pre-heater downcomer duct. IV – For Duct with connecting equipments. V – For Duct subjected to different temperatures. VI – For Expansion Joint located nearer to process damper. VII – For Duct subjected to transverse/angular expansion. Exercises.

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Introduction:-

The reasons for organizing this presentation are:-

To minimize expansion joint problem/failure at project sites.

To minimize PL5 dependencies on Plant Utilities.

To establish a common platform interms of understanding expansion joint terminology, calculation, behavior and documentation.

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Definition and Application:-

Expansion Joint is an flexible connector designed to perform the following four major task:-

To allow expansion and contraction of the duct due to temperature changes.

To provide isolation of a component to minimize the effects of vibration and noise.

To allow movement of component during process operation.

To aid in installation or removal of large components and erection tolerances.

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Definition and Application:

Axial Elongation – Dimensional lengthening of

the expansion joint along its longitudinal axis.

Axial Compression – Dimensional shortening of

the expansion joint along its longitudinal axis.

Lateral Movement – Relative displacement of the two ends

of the expansion joint perpendicular to

its longitudinal axis.

Angular Movement – Displacement of the longitudinal axis of

the expansion joint from its initial straight

line position into a circular arc.

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Working Principle:-

Non Metallic Type – Works on the basis of fabric as flexible element formed into

one or maximum two convolution.

Metallic Type – Works on the basis of thin metallic sheets as flexible element

formed into multiple convolutions.

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Metallic versus Non-Metallic Type:

Temperature

Standard rubber joints have an upper range to 230-deg F.

Standard metal joints are designed up to 420-deg F to 1800-deg F. Movements

Rubber joints absorbs far greater lateral movements when compared to metal joints

Similar face to face dimensions. Spring Rates – Defined as the total force required to move an expansion joint

by one inch in any direction.

Rubber Joints – Low spring rate.

Metal Joints – High spring rate. Gas Tightness at all temperature

Rubber Joints – Lower

Metal Joints - Higher

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Basic Consideration:-

Temperature for calculation (T) = design - minimum ambient temperature(If not insulated) and Temperature =design (IF insulated).

Thermal coefficient (a) = 12x10^-6. Length(L):

Length can be calculated from the 1st fixed support to expansion

joint center and Expansion joint center to 2nd Fixed Support. No need to consider any margin for values of expansion joint as it is calculated for

design temperature.

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Basic Consideration:-

If movements acts in same direction then the movements value should be subtracted and vice versa...

For those expansion joints which comes with connecting equipment the movements due to corresponding Connecting equipment also has to be considered.

1. For Cyclone, Temperature should be skin temperature

2. For ESP and other Connecting equipment, movements will be specified in the OL drawings.

3. For mill and cooler as per respective department there will be no movements. For tall elevators and chain conveyors expansion values given in the respective OL/ Supplier drgs

to be considered

Formula:-Increase in length = aTL

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Case wise Methodology: I – For Straight Duct.

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II – For Inclined Duct.

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III – For Pre-heater downcomer duct.

Two different values of temperature must be

considered for calculation

For Cyclone Temperature should be skin temperature

Total axial movement is 35.145+12.48=47.625~50mm

III – For Pre-heater downcomer duct.

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IV – For Duct with connecting equipments.

Movement due to connecting equipment must be taken in to

consideration.

Resultant movement

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V – For Duct subjected to different temperatures.

Two different temperature condition on the same duct.

Two different temperature condition on the same duct.

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VI – For Expansion Joint located nearer to process damper.

During shut off condition the movements due to duct 85-10 will alone exist and movements due to

duct 85-3 will not act So maximum lateral movements is considered and axial movements due to both duct considering working condition..

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VII – For Duct subjected to transverse expansion.

As Axial movement for this expansion joint act in the same direction

the relative value Should be considered ..

As both the lateral values act in two different axis the resultant is taken

(√13.152+21.482)

Two different temperature condition

on the same duct.

Two different temperature condition

on the same duct.

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VIII – Special Case.

In cases like this where the slide support is placed you have to

check the moment acting on the fixed support.

Resultant movement

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Exercise

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Thank you.