ASME and Penstock piping 4

[LVLIIIenger]

We have been fabricating Penstock piping for hydroelectric dams from 6' diameter to 26' diameter. All welding has been in accordance with ASME Section VIII BPVC, and all fabrication is in accordance with ASCE no. 79 my questions are:

1) We now have a customer that states 100% Radiographic testing is required per ASME, I can only find this requirement for lethal service am I missing something?

2) Doesn't any single chamber pressure vessel shop constructed to ASME Section VIII require a U-1A tag?

Thank you in advance for your help,

Sam

Sam Bruno

 

[trottiey]

1) See UW-11(a) for a list of other conditions wher full radiography might be required. Some possible candidates include UW-11(a)(2), if thickness at the welded joint exceeds 1 1/2 in, or UW-11(a)(5) if designing for a joint efficiency of 90% or greater. Read the full code to see what might apply to your design.

2) Yes, Section VIII does require you to mark the vessel with an official Code U Symbol per UG-116. Section VIII also requires all welding to be done by a company holding a Code U Certificate of Authorization. So if your company is doing Section VIII welding, presumably you have a certificate and you have someone in the company who understands all of this.

 

[gtaw]

The first question I would research is whether the dam is located in a state that has adopted ASME. If not, the use of ASME B&PV code is a contractual obligation.

Does the contract state that the design has to be in accordance with ASME B&PV Code Section VIII?

Does the contract state that the fabricator has to hold an ASME Stamp and does the vessel require an ASME Code Stamp?

If the contract states the pentstock has to be fabricated by an ASME Stamp holder, that means the fabricator must hold the proper stamps and there is an AI involved to check the calculations, materials, fabrication, etc.

I worked with a vessel shop that built some vessels that were ASME stamped vessels and they build vessels that were designed and fabricated per ASME, but were not stamped. It depended on where they were being installed and whether the individual state required the ASME stamp or not.

Best regards - Al

 

[stanweld]

I would recommend that you ask the Owner to clarify which Section of the Code that RT must comply. It seems clear that the Owner requires 100% RT of long and circ seams. Acceptance criteria must be established.

 

[Kiwi2671]

Please excuse my ignorance gents but why is piping being fabricated to a pressure vessel code and not a pressure piping code ?
ASME VIII Div 1 Scope Clauses U-1 (d) (e) & (f) appear to exclude this type of piping from the code.
Am I missing something basic here ? (other than it being a contract requirement)
Regards,
Kiwi

 

[stanweld]

Although I have not been associated with penstock fabrication for many, many years, it was not uncommon then for Purchasers to specify welding and design per ASME VIII, Div. 1 with RT per UW-51 or UW-52.

 

[trottiey]

Customers can be interesting beasts, eh? But they're always right; management told me so. I've seen orders to build electrical conduits and hydraulic systems in accordance with Section VIII. It makes the parts a little bit rigid and a tad expensive, but it's all permissible under U-1(c)(2): "the following classes of vessels are not included in the scope of this Division; however, any pressure vessel which meets all the applicable requirements of this Division may be stamped with the Code U Symbol"

And don't get me started about the N-stamped toilet. Suffice it to say that it really did get built, stamped and installed.

 

[waterpipe]

Dear trottiey,
Add to your list overhead cranes that were asked to be built in accordance with Section VIII! I've seen it in a spec.

 

[Duwe6]

The customer is ALWAYS right, as long as his checkbook is open.