Hello everybody,
we are supplier of vacuum valves and the first time of our company life working for US nuclear industry.

Purchasing materials with CMTR is a problem for us:

- could you give us a hint, where to buy fasteners?

We received a list of certified suppliers but haven't got any answer for fasteners so far.

Thanks in advance

Do you have a N certificate of Authorization? If yes, you may certify fasteners as USM or qualify the supplier. If no, I don't see the necessity of having a CMTR
Mauro

anfaenger,

http://cstools.asme.org/holdersearch/index.cfm

On the ASME homepage ther eis a database. If you look for "MO" and for "NPT" you have the suppliers list, just concentrate on the bolting specialists for Bolting.
If you look for Supports, check the "NS" Certificate holder.

Some will not be interested, but this is a beginning.

What kind of FASTENERS are you looking for? Maybe there is somebody interested in offering?
DK

When it comes to fasteners, meeting NCA and NB requirements is a big problem

Fasteners used for pressure retaining bolting need to meet NB requirements along with CMTR as per NCA-3860

But when you look for QSC holders, there are not many fastners suppliers. I could locate only one supplier from the list published in ASME website and he was not ready to supply when we approached him for some small quantity.

Utilizing unqualified source material for fasteners is another big pain. Fastener suppliers do the required material heat treatment in the last stage after cutting and threading to the required dimensions. Hence as per NCA-3855.5, we have to do product analysis on each piece of material which is very impractical in case of fasteners.

Before we proceed further, let us look at their manufacturing sequence

1) Procurement of long bars (may 6-10 meters in length)
2) Identification of bar and product analysis of each bar
3) Cutting the bar to many pieces of required stud length
4) Punching and identification on both faces
5) Chamfering of the edges
6) Threading
7) Heat Treatment (Quenching and tempering or normalizing and tempering)

With very big struggle, we pushed the fastener supplier to do the heat treatment before threading. Nevertheless, the heat treatment cannot be done before cutting the long bar in many pieces because the furnace they employ is a small continuous furnace and it cannot accomodate long bars. Hence utilizing unqualified source material for fasteners is a big problem.

There are only two easy solutions (theoretical) for this problem, but i dont know how far it is practical.

1) Do the required heat treatment at long bar stage not after cutting. In that case, we can do the required product analysis and testing on each bar and not for each stud.

2) Qualify the fastener supplier atleast for heat treatment operation. But this not so simple. It involves qualifying their furnace (proper calibration as per ASTM A991), indoctrination and training of their heat treatment operators

Also do not forget the fracture toughness requirements of NB for fasteners (including studs and nuts).