One of the first questions that needs to be answered is "What is 'it' made of?"
And that is where PMI enters the picture. PMI stands for Positive Material Identification. That used to be a
cumbersome, destructive process. You would gouge out 40-60g of material,
hopefully not contaminating it or destroying the piece, and send it to a lab.
The lab would then analyse the sample and send you a report, days or weeks
later.
Our inspectors use a process that is a lot faster and simpler than
that! The Innov-X Systems α-2000 AS portable X-Ray Fluorescence (XRF) system uses an electric X-Ray tube, an
onboard detector and processor to deliver results from a prepped surface in less
than 30 seconds. No radioactive sources means no regulatory hassle. With a
weight under 5 lbs, it can go anywhere the operator can go.
Sometimes you own or purchase used equipment whose
manufacturer or fabricator has ceased operations. When it comes time to repair or certify it, there's a problem because
capacity and repair procedures are greatly influenced by the material properties involved. PMI and hardness testing can go a long way toward
resolving these questions.
Other times, the issue is that you have purchased materials overseas. It looks like a familiar. It looks like what you have contracted for.
But given past history, you'd like to be sure that the materials that it should have been constructed out of are what it actually is constructed out of.
PMI can determine if that expensive alloy you paid for actually got used in all
the items that were delivered -- and yes, that has been a real-case occurance.
Items that are going to be used in sour-service oilfield operations generally need to be NACE MR0175 compliant and certified.
Items exposed to H2S at typical environmental temperatures will be subject to sulfide stress cracking, which is a form of
hydrogen embrittlement. Items that are too hard, or contain certain kinds of
alloying materials -- primarily nickel -- in larger than permissible quantities
will become subject to immensly destructive corrosion and cracking if exposed to
wet H2S conditions. If you have mill certs for your items like spools,
adapters and other wellhead equipment, then a simple test for hardness will be
the extent of the NDT required to acertain whether your piece can be certified
as NACE MR0175 compliant. When you don't have mill certs -- well, that's
when PMI is a very, very handy thing to have avaliable.