Hello, Hayden!

I have an pipe which can have a condition rating from 1-5.

1 being perfect and 5 being worst.

It is at 8 yrs old and has a condition rating of 3.5.

What formula can I use to calculate to calculate where this pipe design life finshes?

It is not straight line, it is an ever decreasing curve.

With no more information, we mustthe form of the function.guess

Assuming it is anexponentialfunction, we can solve it.

The condition function would have the form: .

. . where is the initial rating and is a constant to be determined.

Assuming that a brand-new pipe is perfect, we have:

. . So the function is: .

Your pipe is 8 years old and has a rating of

. . The equation becomes: .

. . Hence: .

The condition function is: .

I assume that, when the pipe's condition has a rating of 5, it is replaced.

When does this happen? .When is ?

We have: .

Hence, we can expect to retire any new pipe in about 10.3 years.

Your pipe has about 2.3 more years of useful life.