Seal of a Large High Performance Pump – A Big “Bomb ...€¦ · Technology, Together, For You...

Technology, Together, For You

Seal of a Large High Performance Pump – A Big ”Bomb” with a Short Fuse?J. Baumgartner & T. Johne | R&D – Mechanical Integrity | June 14, 2017

GT Global Technology | Technology, Together, For You June 14, 2017 © Sulzer Ltd2

THE SAFE HARBOR STATEMENT UNDER THE US PRIVATESECURITIES LITIGATION REFORM ACT 1995

This presentation may contain forward-looking statements, including but not limited to, projections of financial developments, market activities or future performance of products and solutions, containing risks and uncertainties. These forward-looking statements are subject to change based on known or unknown risks and various other factors, which could cause the actual results or performance to differ materially from the statements made herein.

GT Global Technology | Technology, Together, For You June 14, 2017 © Sulzer Ltd

1986 the disaster happened

The shuttle exploded after the liftoff

A tiny seal can have a huge impact

NASA Space Shuttle “Challenger”

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Sources: - https://history.nasa.gov/rogersrep/v1p26.htm- Wikipedia


1 Seal design for 6 variations

Modular Design

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ITO-Seal


Modular Design

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Hea

d

Volumetric Flow


Machining tolerances fits

Assembly and maintenance work

Test sequence

Extrusion of the seal

Thermoshock bearing pressure?

Thermal distortion of the casing tightness?

Fatigue

Static plastic collapse

Modular design

Material definition / behavior

What to consider?

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Source: Internet


Combinations

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Source: Internet


Advice: take your time and think about the possible model combinations before creating single models.

Model combinations have lots of positive effects: Save money and time

Less effort and a better overview for the report

Less effort for later revisions

The reviewer saves time and gets a better overview, which improves the quality of the investigation.

Quality audit

Reliability of the engineer’s work

Combinations

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Sav

ings

Source: Internet


Collection of all failure modes and failure causes that could occur

Cover all of the failures with the minimum number of models

Failure Mode Table

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Failure Modes and Loading Conditions

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Physical Effect (shown in a log p-h-diagram) Isothermal expansion of water at 220 °C

Expansion from 820 bar down to environmental pressure of 1 bar

the water vaporizes hot vapor at 220 °C gets blown out!

Leakage – Big “Bomb” with a Short Fuse

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Source: Internet


2-D-Axisymmetric

Fits considered in contact offset

FEM Model

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Pressure chamber 1

Pressure chamber 2


Hydrotest sequence tightness

Tightness

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Linear material Higher material resistance, which is

conservative for evaluating tightness. The seal gets at a higher pressure into touch with the barrel.

Elastic-plastic material All element locations over yield stress, the

material has a lower young’s modulus. The seal gets at lower pressure into touch to the barrel.

Tightness

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Impacts on tightness:

The chosen material behavior

Real yield strength of the material from the supplier!


Not such an obvious parameter but is has a big impact.

Minimum Clearance– Bearing pressure

– Plastic deformation

Middle Clearance– Plastic deformation

Maximum Clearance– Fatigue

– Leakage

Manufacturing Driven Parameter

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Cle

aran

ce


Radial plastic deformation after load (unload case)

Min. clearance: Disassemble it out of the same barrel

Mid clearance: Assemble it into a new barrel

Plastic Deformation

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Stage Casing

Barrel

Cle

aran

ce

(Nominal diameter)

Stage Casing

Barrel

Cle

aran

ce

(Nominal diameter)


Plastic Deformation

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Modular design - does it fit into a new barrel after unload?

Is it demountable or does it stuck to the barrel?


A simple 2D FEM model

Not all parameters are so obvious

Invest at the beginning time

Important are the thoughts, decisions and the approach which the analyst has to make in advance.

Conclusion

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Seal of a Large High Performance Pump – A Big “Bomb ...€¦ · Technology, Together, For You...

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