drill stems have a varied life. They usually fail due to “bending” while drilling and getting caught in a “coke bed that moves”. Sometimes these are straightened and reused but often just replaced. Drill stems have also failed due to corrosion at the treaded area. this is caused most often by high PH water. Adjust the water, replace the section and that usually does the job. There have been a few failures in our industry due to poor manufacturers design or production. the drill stem threads are not cut “deep” enough. I have not heard of drill stems losing dia to the point they fail or must be replaced except maybe a very rare case. Sounds like “erosion”.
I would ensure the metallurgy is correct and that they are being manufactured correctly. Check the water PH and trend for 6mo.
Jim Blevins – Chevron