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”
3
Sources: - https://history.nasa.gov/rogersrep/v1p26.htm- Wikipedia
GT Global Technology | Technology, Together, For You June 14, 2017 © Sulzer Ltd
1 Seal design for 6 variations
Modular Design
4
ITO-Seal
GT Global Technology | Technology, Together, For You June 14, 2017 © Sulzer Ltd
Modular Design
5
Hea
d
Volumetric Flow
GT Global Technology | Technology, Together, For You June 14, 2017 © Sulzer Ltd
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?
6
Source: Internet
GT Global Technology | Technology, Together, For You June 14, 2017 © Sulzer Ltd
Combinations
7
Source: Internet
GT Global Technology | Technology, Together, For You June 14, 2017 © Sulzer Ltd
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
8
Sav
ings
Source: Internet
GT Global Technology | Technology, Together, For You June 14, 2017 © Sulzer Ltd
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
9
GT Global Technology | Technology, Together, For You June 14, 2017 © Sulzer Ltd
Failure Modes and Loading Conditions
10
GT Global Technology | Technology, Together, For You June 14, 2017 © Sulzer Ltd
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
11
Source: Internet
GT Global Technology | Technology, Together, For You June 14, 2017 © Sulzer Ltd
2-D-Axisymmetric
Fits considered in contact offset
FEM Model
12
Pressure chamber 1
Pressure chamber 2
GT Global Technology | Technology, Together, For You June 14, 2017 © Sulzer Ltd
Hydrotest sequence tightness
Tightness
13
GT Global Technology | Technology, Together, For You June 14, 2017 © Sulzer Ltd
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
14
Impacts on tightness:
The chosen material behavior
Real yield strength of the material from the supplier!
GT Global Technology | Technology, Together, For You June 14, 2017 © Sulzer Ltd
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
15
Cle
aran
ce
GT Global Technology | Technology, Together, For You June 14, 2017 © Sulzer Ltd
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
16
Stage Casing
Barrel
Cle
aran
ce
(Nominal diameter)
Stage Casing
Barrel
Cle
aran
ce
(Nominal diameter)
GT Global Technology | Technology, Together, For You June 14, 2017 © Sulzer Ltd
Plastic Deformation
17
Modular design - does it fit into a new barrel after unload?
Is it demountable or does it stuck to the barrel?
GT Global Technology | Technology, Together, For You June 14, 2017 © Sulzer Ltd
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
18
GT Global Technology | Technology, Together, For You June 14, 2017 © Sulzer Ltd19
Thanks for your attention!
Top Related