Review of Design Drawing for ASME Sec III

[GrimesFrank]

I just want to take a straw poll here as I've hit an odd item.
When reviewing a design drawing (i.e. used in design report), what details do you look for as a minimum for acceptance?
I ask because I have received a drawing that is light in details (basically a pictorial of the fitting) and when I have questioned the vendor I was asked what the 'code' requirements were. I thought of course ASME would've covered this and so I went searching, NQA...nothing....NCA....nothing...just some generic text on enough to show the design. I may be blind if anyone can help I'd appreciate it.

Today is gone. Today was fun.
Tomorrow is another one.
Every day, from here to there,
funny things are everywhere. ~'Dr.' Theodor Geisel

 

[gr2vessels]

Frank,
The code does address the issue of documentation required for the parts manufactured by other than the vessel fabricator, for the use/installation on a pressure vessel (refer Partial Data Report in UG-120(c)). However, you have mentioned "fitting" and I'm not sure, is it any of the ASME B16....fittings, governed by the relevant standard or you just use a bit loosely this word. You might have noticed that only documented/approved/certified/stamped/marked items may be used on the pressure vessels fabricated in accordance with ASME code (or any recognised pressure vessel code). Obviously, it is your responsibility to assess the origin of such certification and the worth of it. This Quick Closure might be installed by this reputed French company on the Gas Filter Coalescer, but you got every right to question the documentation certified and issued in China for that closure (UG-120(c)).
The part drawing must include the design conditions specified by you or the extent of process conditions the part was designed for. Also, basic dimensions and detailed dimensions for assembly/installation/welding, weight if significant, MOC and heat treatment details, date of the last revision and perhaps a stamp for actuality of the part. A pretty picture of a pressure bearing component, welded in a pressure vessel assembly, without all the above details should not be accepted as a document.
This should get you going, give us some more details ...
cheers,
gr2vessels

 

[MJCronin]

Frank,

In my opinion, you have put your finger on the issue that seperates the men from the boys - the degree of accuracy and detail in design drawings.

In recent years, working for several large AE firms, I have found a tendency for the specific vessel drawing details to be spelled out in the purchase order. In some extreme cases an example was provided to show the bidder exactly what was required. Tank and pressure vessel fabricators are suffering from the same malaise as the rest of US industry -- the retirement and disgust of the knowledgeable

You probably would be well served by giving the fabricator some example drawings from his competitors or by purchasing a book on equipment drafting.

Here is one of many:

http://www.amazon.com/exec/obidos/ASIN/0824707400

Some people sell this as a service:

http://www.wech.com.my/pvdesign.html

regards

-MJC

 

[vesselfab]

It all depends on the part.

of course there should be dimensions and material specifications sufficient to build from showing the finished product. Also andy welds should be shown with full description or welding symbol.

Any required stamping and nde required on the part.

As for design information, if design is a function of the fabricator/supplier, then yes. If design is not required by fabricator, then no, it doesn't have to be there.

 

[doct9960]

GrimesFrank,

What type of fitting? Is it a standard item (among those listed in Table NC-3132-1) or a manufacturer's standard?

 

[GrimesFrank]

Thanks people,

The 'fitting' is a 1/2" NPT ported solenoid spool valve, specifically a Marotta. Design conditions; 2700 psi(g) @ 150ºF, D2O (pH 6-11).

Details of drawing
Whats there
- Sectional view with subparts identified with Parts List
- Design specifications are on it
- Overall 'envelope' dimensions.
- Estimated weight
- Maximum Cv

What else I expect when compared to my other valve vendors
- NDE details
- Weld details
- HT details
- identfication of location and thickness of minimum wall
- assembly torques for all fasteners
- any ANSI class rating and CWP
- Model/Assembly # & Serials for purchased valves
- any actuator requirement details (electrical or pneumatic)

Am I overstepping the industry norm?
Here was the big flag for me. The drawing didn't state what type of valve it was (3-way/2-way, 2 position?, indent?, etc)

Another question. Marotta is replacing a valve they haven't made in years. They sent me their old (70's) print of the valve. Should I be expecting a laundry list of concessions from them when they try to construct this valve and material that was readily available in 1974 is not used (more expensive) today?



Today is gone. Today was fun.
Tomorrow is another one.
Every day, from here to there,
funny things are everywhere. ~'Dr.' Theodor Geisel

 

[gr2vessels]

The design is probably a "registered" one, hence there is a production ITP signed off by the manufacturer for compliance with the original design. There you'll find the results for NDE, compliance with the approved welding procedure, the assembly torque could be a "tick" - As Per Bolting Specification - etc... If there is a code number for the valve in top of the mentioned drawing, is likely the code number is tabulated in the main catalogue, which is listing the pressure/temperature rating and many other details, including info on the suitable type of actuator to be used. I'm also sure the main catalogue would list the type of valve (2 or 3 way valve, positioner,...) and all the accessories available for this valve. As for the replacement valve, you should get the actual valve drawing, not the old, obsolete one.
I assume that for a small fee, the company may send you a copy of those details you have expected to come automatically, as standard documentation. However, the guarantees given for the valve imply that all those details have been completed to the satisfaction of the applicable codes, quality control and industry standards.
cheers,
gr2vessels