NDE of Section VIII, Div. 1 Vessel

[Blizzardo]

All,

We are working on an ASME Section VIII, Div. 1 pressure vessel installed in British Columbia, Canada. The vessel is SA516 (P1) material with a 2.5" wall thickness. The vessel is 200' high and 30' in diameter. The vessel operates at 32-350F and at 150 PSI. We are installing several nozzles into the vessel wall. The nozzles are through-wall design, no re-pads. The nozzles are 6" sch. 80 seamless stainless pipe (P10H) for extraction and 10" diameter x 3" thick plate (machined to a 3" nozzle for instrumentation). We are welding out the nozzles with 309L.

My questions relate to the required NDE and hydrotesting for the install of the nozzles. For the required NDE under Section VIII, the design engineer for the nozzles has indicated 100% VT, 100% PT and 25% RT or UT. We are opting for UT in lieu of RT to improve schedule and safety for the project. My question is, does the engineer's indication of NDE required for the work meet the requirements of Section VIII, or is additional NDE required?

On the hydrotest piece, the Owner of the vessel wants to forego the requirement to hydrotest and instead perform a service test of the vessel to normal operating pressure. Considering the size of the vessel, this is reasonable and practical due to the volume of the vessel. The regional Authorized Inspector is accepting of this plan, however I an asking the forum if this is allowed under the applicable Code (ASME Section VIII).

Any assistance in interpretation of the Code would be greatly appreciated.

Thank you.

Blizzardo

 

[TGS4]

Re hydrotest- if the AI is OK with it, then it's OK.

Re NDE - never trust the design engineer (speaking as a design engineer). The answer to your specific question is that it depends. Discuss with your AI.

Please ask your design engineer if they have considered fatigue - the differential thermal expansion over the temperature range that you indicated will give rise to substantial thermal stresses. That could impact their NDE.

 

[Blizzardo]

TGS4 - Thank you for the expedited reply.

The challenge for us for our project is that the AI does not want to be overly prescriptive and rather wants the contractor (us), the design engineer (our client), the vessel Owner and the NDE group to coordinate and agree to the type and extent of NDE. For us as the contractor, I'm really looking for an accurate interpretation of Section VIII in so far as what the Code demands for the type and extent of NDE.

 

[r6155]

Leak testing is required, try with
BUBBLE TEST — VACUUM BOX TECHNIQUE (special shape)
See ASME PCC-2

Regards
r6155