Horizontal Joint Gasket Failure Feedwater Systems Reliability Users Group Presenter: Kurt J Weis...

Horizontal Joint Gasket Failure

• Feedwater Systems Reliability

• Users Group

• Presenter:

• Kurt J Weis

• Rotating Equipment Repair, Inc.

Finite Element AnalysisTo resolve split case gasket failure

Ingersoll Rand 12 Stage Split Case Pump

4X10-12DAH-E

Equipment Analyzed

• Ingersoll Rand 12 stage spilt case pump

• 4X10-12DAH-E

• 3000-3600psi operating range

Failure Mode: Internal RecirculationMTBF: <2500 hours

Previous Repair Solutions

• Different Gasket materials

• Increased Stud Preload (Use of “Super Studs”)

• Beveled or Tapered Joint

Analyzing the Failure Mode• Gasket has minimal contact pressure between

stages causing internal recirculation• Contact pressure can be analyzed with FEA• Accurate full casing model required to perform

FEA

Creating Accurate Model• White Light Scanner/Digitizer gathered 3D

point cloud data needed to create a model.

Creating Model

• Using point cloud data, a Pro-E solid model-assembly was created.

Model Constraints

• CA6NM Material, a 400 series stainless steel cast material

• Feet restricted to horizontal movement only• Internal pressures

Pressure Distribution

Analysis 1• Standard Casing, 75% stud preload, (original design)

to establish baseline.

Analysis 2

• Standard Casing, 112% stud preload

Beveled Casing, Analysis 3

Analysis 3• Beveled or Tapered Casing, 75% Stud Preload

Additional Row of Studs, Analysis 4

Analysis 4• Additional Row of studs, 75% Stud Preload

Analysis 5• Additional Row of studs and beveled joint, 75% Stud Preload

• The final design choice: Additional row of studs with no joint bevel

Manufacturing

Manufacturing

Completed Product

Completed Product

Completed Product

Results• Three pumps rebuilt with this modification.

No pumps have been removed from service yet.

• First installed pump has over 17000 hours on it, with no degradation in performance.

Reverse Engineering

• The same technology can be used for reverse engineering impellers

ExampleCirculating Water Pump Impeller Failure

Large Horizontal Circ Pump Impeller• Impeller was scanned and modeled using same technologies

Pattern Fabrication using Model

Casting Poured with CA6NM

Machining

Old to New Impeller Comparison

Old to New Impeller Comparison

Deviation Report

Completed Product

Completed Product

Completed Product Installed

Questions?