The limits stand individually. They cannot be relaxed if the other parameters are lower than their respective limits.

Also, remember that welds are not covered.

Steve Jones
Corrosion Management Consultant

www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

And other forms of corrosion are not covered either.
It is up to you to address those as well.

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P.E. Metallurgy, consulting work welcomed

Thanks Mr. Jones and EdStainless.
Your replies are not clear to me. Please elaborate. I was looking for yes / no type reply.
My pipe class shows 316L pipe used upto 250 deg C.
What is the maximum temp limit of 316L per ISO 15156-3.

The 250C is strictly related to temperature and pressure.
Once you start adding any corrosion effects those will only reduce the maximum service temperature.
Looking at just pH and Cl you will run into pitting/cervice corrosion limits.
And then you need to consider the H2S related issues.
This is called engineering, the solving of problems.

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P.E. Metallurgy, consulting work welcomed

The piping engineers putting the piping class together have no clue about corrosion other than being told what corrosion allowance is required (in this case it should be zero). They work purely from mechanical and availability considerations. So, mechanically, the piping class might be able to go to 250 deg C, but from a corrosion point of view it could be inappropriate.

There are three ways to allow 250 deg C:

1. Absolute confidence in a maximum 50 ppm of chloride

2. Performing a suitable laboratory qualification test programme

3. The pipe is going into equipment that has already performed satisfactorily for a minimum of 2 years in the specific environment.

Good luck

Steve Jones
Corrosion Management Consultant

www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.