Thinning Rate

[Cessh]

Dear Senior,

Does anyone knows what is the "best practice" equation used to calculate Boiler tube thinning rate given that you know it's initial tube thickness, last measured thickness and operating hours? in order to predict whether in the next overhaul we should replace the tube or not..

NB: ASME or BABCOCK & WILCOX equation is ok. Thx.

Best Regards

 

[metengr]

The best practice is to measure wall thickness during either scheduled or forced outages, and compare with original tube wall thickness to determine wastage rate. The measured thickness data can be plotted over time to establish a tube wastage rate.

 

[Cessh]

How about using this equation:

Thinning Rate (mm/hours) = (Wi-Wf) / (Wi*running hours)

Wi = initial thickness
Wf = final measured thickness

Is anyone familiar with the equation above? Is it correct?

Is there any equation from ASME that tells how to find the thinning rate of boiler tubes?

 

[metengr]

1. You do not need Wi thickness in the denominator, only service hours; Wi-Wf/service hours.
2. Not in ASME B&PV Code.