nafr-tfv00-0000-tr turbine and valve allowable stresses

7/30/2019 NAFR-TFV00-0000-TR Turbine and Valve Allowable Stresses

1/6

2x 60 MW NAFRA HE Project

Allowable StressesRevision -

Summarisation ofDesign Guidelines of Allowable Stress Levels for Turbine and

Spherical Valve

NAFRA HEP

143525382.doc Page 1 of 6


2/6



TABLEOF CONTENTS

1 Voith Hydro Standard for Allowable Stresses 3

2 Definitions 3

3 Loading Cases 3

Annex 1 Basic Loading Case Definitions 5

A1.1 Turbine and MIV 5

143525382.doc Page 2 of 6


3/6



1 Voith Hydro Standard for Allowable StressesThe allowable stresses are determined as a fraction of the minimum yield strength. Theactual combined stresses calculated according to von Mises Criterion shall not exceed thefollowing allowable values:

2 Definitions

Rp Yield strength or 0,2% offset from the linear region of elongation.

Rm Ultimate strength of the material.

Stress value to be evaluated for a component, typically the combined stress

according to von Mises criterion. For different stress classes, see chapter 1.

allow Stress level not to be exceeded, typically defined as a fraction of Rp or Rm.

aD Amplitude of stress which defines the limit of endurance of a material under cyclic

strain for a given number of load cycles.

3 Loading Cases

There are three basic loading cases to be evaluated:

143525382.doc Page 3 of 6


4/6



Such loading case definitions are linked to the stress levels laid down in chapter 1.

143525382.doc Page 4 of 6


5/6



Annex 1 Basic Loading Case DefinitionsA1.1 Turbine and MIV

FRANCIS and PUMP TURBINES

Components Operating Loading Case Exceptional Loading Case Extreme Loading Case

Runner

Pump turbines

Max. Head

Max. Output

Speed no Load

Pump start Max.

Head/Max. Input

Min. Head/Max. Input

Max. Runaway

Shaft Max. Output 3-phase Short Circuit 2-phase Short Circuit

120 Synchronization

Failure

Head Cover, Bottom

Ring Discharge

Ring

Pump turbines

Max. Head/Max. Output

Full Load Rejection

Pump Start

Pump Load Rejection

Spiral Case

Stay Ring

Max. static Head incl.

Water Hammer

Pressure Test

Installation/Embedment

Wicket Gates Max. static Head + Gate

Squeeze

Effective pressure

difference during LoadRejection

Max. static Head + Water

Hammer, safety elementactivated

Closing of Distributor at

Runaway at Max. Headand Max. Opening

Operating Ring Max. torque on Wicket

Gates, Wicket Gatespre-stressed

Shear pin failure of one

Wicket Gate under closingduring Load Rejection.

One Servomotor blocked

operation againstengaged Lock.

Distributor

Servomotor

Max. Oil Pressure and

Max. force

Pressure Test

Draft Tube Max. Tail Water pressure

inside

Embedment

Max. Tail Water pressure

outside plus 5m vacuumbelow Runner

MIV -SPHERICAL VALVE

Valve Body Max. static Head + Water

Hammer

Maintenance Seal engaged

(effective Penstock

Pressure with Valve closed

and other Units facing Full

Load Rejection)

Pressure Test

143525382.doc Page 5 of 6


6/6



Valve Rotor Effective Pressure during

closing at Max. static

Head at normal Flow

Penstock Pressure with

Valve closed and other

Units facing Full Load

Rejection


(Penstock Pressure with



Rejection)

Pressure Test with Rotor

closed (if no downstream

Test Head foreseen)

Trunnions Effective Pressure during

closing at Max. static

Head at normal Flow

Penstock Pressure with



Rejection


(Penstock Pressure with

Valve closed and other Units

facing Full Load Rejection)

Pressure Test with Rotor

closed (if no downstream

Test Head foreseen)

143525382.doc Page 6 of 6

nafr-tfv00-0000-tr turbine and valve allowable stresses

Documents