Piping Design & Applications Workshop

Rev. 9-4-03

Piping Design & Applications Workshop

Part C

Piping Design & Applications Workshop

Part C

Don Frikken – Becht Engineering Company

C-2

The process of calculating the strains, and resultant stresses and forces in a piping system to determine if the system

Flexibility AnalysisFlexibility Analysis

has adequate supporthas sufficient flexibility to safely accommodate changes in length resulting from temperature variationsexerts sufficiently low reaction forces at restraints and equipment

Piping Design & Applications Workshop

Rev. 9-4-03

C-3

Flexibility Analysis – adequate supportFlexibility Analysis – adequate support

A piping system has adequate support if:The calculated stresses do not exceed the allowableThere are no sags greater than about 0.3 inches (8 mm), andThe system looks adequately supported to those people who have to work around the piping.

C-4

Flexibility Analysis – change in lengthFlexibility Analysis – change in lengthChanges in length resulting from temperature variations

Piping Design & Applications Workshop

Rev. 9-4-03

C-5

Flexibility Analysis – change in lengthFlexibility Analysis – change in lengthHow much change in length due to temperature variation?

ΔL = α * ΔT * L

Whereα = coefficient of thermal expansion (1/ºF, 1/ºC)∆T = change in temperature (ºF, ºC)L = original length∆L = change in length

See table in supplement for values for α.

C-6

Flexibility Analysis WorkshopFlexibility Analysis Workshop

How much does a 20 ft (6 m) long segment of stainless steel pipe change in length due to temperature increasing from -20ºF (-30ºC) to 600ºF (315ºC)?

Piping Design & Applications Workshop

Rev. 9-4-03

C-7

Flexibility Analysis – change in lengthFlexibility Analysis – change in length

A piping system has sufficient flexibility to safely accommodate changes in length resulting from temperature variations if:

The calculated stress ranges do not exceed the allowable, andThe system looks adequately flexible to those people who have to work around the piping.

C-8

Flexibility Analysis – reactionsFlexibility Analysis – reactionsA piping system exerts sufficiently low reaction forces at restraints and equipment if:

The calculated reactions at supports do not exceed the design loads, andThe calculated reactions at equipment are less than the allowable.

Piping Design & Applications Workshop

Rev. 9-4-03

C-9

Flexibility Analysis – reactionsFlexibility Analysis – reactions

Excessive reactions at equipment cause:Cracks at the base of nozzlesDistortion of rotating equipment casings, which

Shortens life of seals and bearingsMay result in rubbing contact of close-clearance rotating elements

C-10

Flexibility Analysis – reactionsFlexibility Analysis – reactionsAllowed loads for equipment:

Equipment Item Industry StandardCentrifugal Pumps API 610

Centrifugal Compressors API 617

Air-Cooled Heat Exchangers API 661

Pressure Vessel and Shell-and-Tube Heat Exchanger Nozzles

WRC 107

Tank Nozzles API 650

Steam Turbines NEMA SM-23

Piping Design & Applications Workshop

Rev. 9-4-03

C-11

Proposed SystemProposed System

NPS 4Carbon SteelAmbient to 600°F (315°C)SG contents = 1.0

C-12

Adequate SupportAdequate SupportCheck Deflections

Deflected 0.4” (10 mm) Marginal:> 0.3” (8 mm)

NormalMaximum

Piping Design & Applications Workshop

Rev. 9-4-03

C-13

45%10%

Check Reactions

Adequate SupportAdequate Support

100% =1020#

(4500 N)

5%

ReactionsPoorly

Distributed

C-14

Check Stresses

Adequate SupportAdequate Support

Max. is 66% of allowable

StressesOK

Piping Design & Applications Workshop

Rev. 9-4-03

C-15

45 to 30%10 to 15%

Revised System (Added Support)

Max. Displacement –0.4 to 0.1” (10 to 2 mm)

Max. Stress –66% to 34% of allowable

Adequate SupportAdequate Support

100 to 60% 5 to 10%

DisplacementsStresses &Reactions

All OK0 to 45%

C-16

Sufficient FlexibilitySufficient Flexibility

Check Deflections

0.4” (10 mm)

0.9” (23 mm)

DeflectionsOK

Piping Design & Applications Workshop

Rev. 9-4-03

C-17

Sufficient FlexibilitySufficient Flexibility

Check Reactions

5% 20% 100% =1240# (5520 N)

95% 10%

ReactionsHigh, PoorlyDistributed

C-18

Sufficient FlexibilitySufficient FlexibilityCheck Stresses

Max. is 79% of allowable StressesOK

Piping Design & Applications Workshop

Rev. 9-4-03

C-19

Sufficient FlexibilitySufficient Flexibility

5 to 5% 20 to 0% 100 to 10%

95 to 0% 10 to 15%

Revised System (Added SpringSupport)

Max. Displacement –0.9 to 1.5” (23 to 38 mm)

Max. Stress –79% to 48% of allowable Displacements

Stresses &Reactions

All OK

100% =1240# (5520 N)

C-20

The process of calculating the strains, and resultant stresses and forces in a piping system to determine if the system

Flexibility AnalysisFlexibility Analysis

has adequate supporthas sufficient flexibility to safely accommodate changes in length resulting from temperature variationsexerts sufficiently low reaction forces at restraints and equipment

Piping Design & Applications Workshop

Rev. 9-4-03

C-21

Designing With Expansion JointsDesigning With Expansion Joints

Types of Expansion JointsPressure ThrustInstallation of Expansion Joints

(Hanjo) (General Rubber) (Hyspan)

C-22

Types of Expansion JointsTypes of Expansion Joints

Ball Slip

Rubber Bellows Metal Bellows

Piping Design & Applications Workshop

Rev. 9-4-03

C-23

Pressure ThrustPressure Thrust

Expansion Joint Manufacturer’s Association (EJMA)

C-24

Pressure ThrustPressure Thrust

(EJMA)

Which types of expansion joints have this problem?

Piping Design & Applications Workshop

Rev. 9-4-03

C-25

Pressure ThrustPressure Thrust

For a bellow type expansion joint, the pressure thrust force is

F = P * π * d2

4Where

P = pressure d = pitch diameter of bellows

C-26

Pressure Thrust WorkshopPressure Thrust Workshop

What is the apparent change in the weight of a vessel caused by increasing the pressure by 100 psi (700 kPa)?

See the supplement, page 42.

Piping Design & Applications Workshop

Rev. 9-4-03

C-27

Installation of Expansion JointsInstallation of Expansion Joints

Anchors must be designed for full pressure thrust based on test pressure.

(EJMA)

C-28

Bellows MovementBellows Movement

Axial (EJMA) Rotation (EJMA)

Piping Design & Applications Workshop

Rev. 9-4-03

C-29

Bellows MovementBellows Movement

Lateral (EJMA)Inefficient for bellows

Efficient use of bellows for Lateral movement (EJMA)

C-30

Universal Expansion JointUniversal Expansion Joint

Piping Technology & Products(PTP) (PTP)

Piping Design & Applications Workshop

Rev. 9-4-03

C-31

Universal Expansion JointUniversal Expansion Joint

In-plane application(EJMA)

3-dimensional application(EJMA)

C-32

Hinged Expansion JointHinged Expansion Joint

(EJMA) (Adsco) (Hae Jo Industrial)

Piping Design & Applications Workshop

Rev. 9-4-03

C-33

Hinged Expansion JointHinged Expansion Joint

(EJMA)

(EJMA)

C-34

Gimbal Expansion JointGimbal Expansion Joint

(EJMA) (Adsco) (Hae Jo Industrial)

Piping Design & Applications Workshop

Rev. 9-4-03

C-35

Gimbal Expansion JointGimbal Expansion Joint

(EJMA)

C-36

Pressure Balanced Expansion JointPressure Balanced Expansion Joint

Piping Design & Applications Workshop

Rev. 9-4-03

C-37

Pressure Balanced Expansion JointPressure Balanced Expansion Joint

(EJMA) (Hae Jo Industrial)

C-38

Pressure Balanced Expansion JointPressure Balanced Expansion Joint

(EJMA)

(EJMA)

Piping Design & Applications Workshop

Rev. 9-4-03

C-39

Shipping BracesShipping Braces