Mill Cert vs PMI

[elm383]

Good day to all.

Main question: Can PMI substitute a 3.1 mill certificate?

Some Context:
- Specification document states this as a general requirement. Not really mentioning which components requires it or which isn't.
- We are system integrators that integrate components to build hydraulic/pneumatic controls for offshore instrumentation and control purposes.
- All of the components consists of small instrument valves and sensors; at most having 1/2" ports and tube connections (usually 3/8"), unlike piping components.
- Pressures can go upto 150psi on certain loops, or upto 6000psi in other loops though.
- Component's material is mostly SS316.
- Not all instrument manufacturer can provide 3.1 mill certificate for all of their products.

Follow up question:
- Is mill certificate really required not PMI for the above context?
- How to know which components would actually require mill cert. or not? Client rep. is not helping. For him/her, it should be "EV-ER-Y-THING".

All of your insights are truly appreciated. Best regards.

 

[Arkaprava Ghosh]

EN 10204 3.1 mill certificate is generally required for all components. It states that the QC department of manufacturer should certify the material, which is basically present is most ISO 9001 certified organizations.

PMI cannot replace a 3.1 certification, since PMI is only considered as a verification program. It cannot form a basis for rejection of material, it can only raise a doubt over the chemical composition of material, based on which product analysis shall be carried out (mainly OES spark methods). All ASME / ASTM material specifications require heat analysis to be carried out, none of them specify PMI as a substitution method for heat analysis or product analysis.

 

[gtaw]

PMI may do a fine job of identifying the metallic elements, but they do a poor job of identifying the lighter elements like carbon.

Best regards - Al

 

[elm383]

Thanks for the reply!

What if the materials does not fall under ASME/ASTM material specifications?

 

[SJones]

The product specification should detail the requirements for determination of chemical composition. If it does not, then the purchaser should define the requirements in the purchase order. If the purchaser fails to do that, then it's pot luck.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

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

 

[elm383]

A follow up question:

Do all the parts of an item (i.e. a valve) require mill cert? If we look at a more complex valve, it may contain multiple parts that may be produced from different raw materials. Does it mean that each part would have it's own mill cert? How do we identify which mill cert belongs to which part, if the part is very small and/or can't/doesn't have the heat number on it?

Again, thank you in advance for all the advice. I really appreciate it.