pipe stress amp support

7/29/2019 Pipe Stress Amp Support

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Piping Stress Analysis


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Overview

What is Flexibility Analysis ?

Analytical Method to calculate Displacement & Stresses

Guidelines for lines connected to Critical Equipment

Fundamentals of Primary & Secondary stresses

Spring Supports

Various Load Cases

Stress Analysis

Expansion Joints

Checking Flexibility using Nomographs

Fundamentals of Buried Pipe Analysis

Stress Analysis using CAESAR-II

Stress Analysis- Responsibilities & Methodology


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Flexibility

Temperature

COLD

HO

T

Stress Analysis

Not Flexible

Flexible

What is Flexibility of the Piping System?

Ability to absorb thermal growth of the piping system


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Overview

What is Flexibility of the Piping System?

Stress Analysis

Piping system shall be designed to have sufficientflexibility to prevent pipe movements from causing

failure from overstress, leakage at joints or detrimentaldistortion of connected equipment resulting from

excessive thrusts and moments

How to provide Flexibility in the Piping system ?

By change in direction using BENDS, utilising

Expansion joints

Ability to absorb thermal growth of the piping system

What code states about Flexibility in the Piping system ?

HOW to conclude whether system is Flexible or not ?


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Sustained (Primary) Stresses


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Types of STRESSES in the Piping SystemPrimary Stresses

Direct Shear and Bending in nature Caused due to-

Dead Weight Internal Pressure Occasional Load

Pipe Fluid Piping Component Snow/ Ice

Wind Seismic Load PRV Thrust

Secondary Stresses

Bending (cyclic) in nature Caused due to- Thermal Expansion Equipment Piping System

Local Stresses

Localised Bending and Shear in nature Caused due to-

Local load like load on welded lug on pipe

Stress Analysis


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Code Allowable STRESSES

Primary Stresses

Checking Criteria

Secondary Stresses

Induced Stresses


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Stress Range- Definition

COLD

HOT

HOT OPERATINGCOLD COLD

AsInstalled

Outer fibre-Tension

At Elbow >>

Thermal exp.

Inner fibre- Compr.

Bending stressesdiminishes due toplastic deformations

Stresses Relaxed

At Elbow >>Outer fibre-Compr.

At Elbow >>

Thermal contraction

Inner fibre- Tension

Stress Loading type - CYCLIC

Failure type - FATIGUE

Failure time - Number of Cycle

Stress Analysis

Conclusion ?


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Allowable Stress Range

Allowable Stress Range ( Sa) = (1.5 x Sh) + (1.5 x Sc) = 1.5 ( Sc +Sh )

Yield Stress ( Sy ) =1.5 x Allowable Tensile Stress ( Sc or Sh)

Provision of Primary stresses = Sh

Reduced allowable = 1.25 ( Sc + Sh) To account for simplification in calcn.

To account for localised stresses

Allowable Stress Range ( Sa) = (1.25 Sc + 0.25 Sh ) x f

f = Stress reduction factor

= 1 For life cycle up to 7000

= 0.9 For life cycle 7001 ~ 14000

= 0.8 For life cycle 14001 ~ 22000 = 0.7 For life cycle 22001 ~ 45000

= 0.6 For life cycle 45001 ~ 100000

= 0.5 For life cycle 100001 & over

Stress Analysis

COLD

HOT


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Stress Evaluation

Temperature

COLD

HOT

L = x L

Linear Coef of thermal expn.( Ref. B31.3, Table C-1 )

Stress = Strain x E

Young Modulus of Elasticity( Ref. B31.3, Table C-6 )

Force = Stress x Area

= 48 (L)2 S / E D

E D / 48 (L)2S =

Guided Cantilever Method

Stress Analysis


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Stress Evaluation-In & Out Plan Bending, SIF

Mi

MtMo

For safe design Se < = Sa

Sb = ( Ii x Mi )2+ ( Io x Mo )2 Z

Ii = SIF factor- In Plane

Io = Sif factor- Out Plane

Z = Sectional Modulus of Elasticity

= 3.142 x ( Do3 - Di3 ) / 32

B 31.3 Table D-1

St = Mt / ( 2 x Z )

Se = Sb2 + 4 x St2

Stress Analysis


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Simplified method to check piping system flexibility

Basis - Code B 31.3 para 319.4.1

COLD

HOT

U

L

D x

( L - U ) 2< = KI F Then Piping is Flexible

D = Pipe OD ( mm )

= Resultant Displacement ( mm )

L = Developed Length ( mtrs )

U = Anchor Distance ( mtrs )

K = 208.3

Limitations

Only two point of fixation

No change in pipe size

No intermediate restraint

Stress Analysis


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Other Methods to check the flexibility

Using Nomographs

To perform quick flexibility check

To estimate preliminary anchor loading for civil structural design

Highly versatile application program

To do preliminary exp.. loop sizing on pipe rack at early stage of the job

To review visual analysis lines to avoid expensive CAESAR analysis

Results are acceptable to world wide Engineering companies

Based on Finite Element Analysis Method

Stress Analysis

Using Computer application - CAESAR-II


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Initial Review

Review Piping Specification Review Piping Study Drawing around critical equipment Identify critical civil structural requirements Review all applicable project standards

Prepare Preliminary Stress Critical Line List

Quick check using Excel spreadsheet for Pipe Wall and Br. Reinf. Calculation

Review Pipe-Rack study layout- Establish preliminary exp.. loop location Establish preliminary Pipe-rack loading for structural design

Detailed Review

Identify CAESAR Stress Models- Include group of lines in single model

Perform detailed stress analysis based on issued stress critical line list

Analyse visual check lines using simplified manual techniques Communicate with civil, Vessel and Mechanical groups for loading

Final Approval

Freeze the stress model based on final isometrics

Documentation of Input and Output Reports

Stress Analysis

General Working Procedures


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Identify StressCritical Lines-

Stress Critical Line

List

ReviewStress

Isometric

Revise thePiping study &

Isometric

FreezeSupporting

arrangement

Approvethe Stress

Isometric

Nozzleloading &

Civil Loading

Acceptable ??

Yes

No

Stress Analysis

General Working Procedures


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Responsibilities of Stress Engineers

Nominated by Chief Piping Engineer Responsible for all Stress and Support related activities

Ensure work carried out per Procedures and Design Basis

Establish the Contract Design Data and Design Philosophy

Issue Stress and Support Design Note

Establish Stress Critical Line List

Stress Group Progress Reporting, Man-hours allocation and

Forecast

Raise the Change order to reflect additional work

Supervise Stress and Support activities

Review Piping Specification for Pipe wall thickness and Branch Calc

Job close-out report for stress and support group

Stress Analysis

Stress Lead Engineer

R

esp

o

nsibil

ities


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Nominated by Chief Piping Engineer/Lead Stress Engineer

Carry out Flexibility analysis

Identify all the load cases to be considered in analysis

Review Study Drawing to ensure sufficient flexibility in critical piping

Identify and review all critical piping supports Summarise Equipment Nozzle Loading communicate to others

Perform flange leakage calculation for high pressure piping

Communicate critical support loading to Civil

Prepare Spring Schedule/Bellow Specification for procurement

Identify requirement of reinforcement pad due to stress consideration

Decide on position of Fixed saddle of horizontal Heat Exch.. and Vessels

Review Vendor data regarding nozzle loading etc..

Documentation of Analysis Reports

Stress Analysis

Responsibilities of Stress Engineers Stress Engineer

R

esp

o

nsibil

ities


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SPRING Supports

Spring Hangers/ supports

Why required ? ? ?

Variable Type Constant Force Type

Types of Spring supports

Principle of working

Terminology

Cold Load Hot Load

Spring Rate Travel

Instruction for Field Installations

Technical Specification

Stress Analysis


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Expansion Bellows

Why to use ? ? ?

Instruction for Field Installations

Why NOT to use ? ? ?

Metallic Bellow

Material of Construction Non- Metallic ( Rubber / Fabric )

Axial Types of Metallic Bellows

Universal Tied Swing

Hinged Gimbal Pressure Balanced

Selection Criteria

Technical Specification

Stress Analysis

Back Thrust of Un-tied bellow


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Piping Supports


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Pipe Supports

Purpose of Support

Pipe support Instructions and Design Guide

Type of Supports

Pipe support Standard

Pipe Support - Trunnion Calculation

Pipe Support - Span Table

Overview


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Purpose of Pipe supports

Purpose

To Support dead weight of Piping system

To absorb wind load and Seismic load

To absorb Vibration in the Piping system

To Suppress the Noise level in the Pulsating Piping systems

To take Expansion load in the Piping system

To absorb Hydraulic Thrust in the Piping system

To Support the system during Shut down/ Maintenance Cond.

To absorb the Pressure Thrust of Bellow

To minimise Pipe Sagging

Pipe Supports


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Types of Pipe supports

Based on Functions

Loose or Resting supports Longitudinal Guide Supports Transverse Guide Supports Anchor Supports Limit Stops

Welded Type

Non- Welded Type

Based on Construction

Rigid Support

Adjustable Supports

Elastic Supports

Bolted Type

Welded Type

Constant Type Variable Type Snubber Type

Pipe Supports


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Types of Pipe supports- Details

U-Bolts and Clamps Shoe Rod Hangers

Welded Type Clamped Type

Secondary Supports

Attachment from Steel Structures

Attachment from RCC Structures

Attachment from Equipment

Primary Supports

Attachment from Grades

Other Supports

Trunnion Supports

PTFE Sliding Supports

Pipe Supports

pipe stress amp support

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