Pressure Vessel Codes - API 510 or NBIC?
 

ASME BPVC-American Society of Mechanical Engineers, Boiler and Pressure Vessel Code

API 510-American Petroleum Institute, Pressure Vessel Inspection Code: Maintenance Inspection, Rating, Repair, and Alteration

NBIC-National Board of Boiler and Pressure Vessel Inspectors-National Board Inspection Code

AI- The authorized inspector defined in the NBIC.

Let’s discuss to what and where each code applies.

The ASME Boiler and Pressure Vessel Code is written for new construction only. The name plate, code symbol stamp, and data report only cover new vessels and the activities of designing, fabricating, and testing new vessels.

Once a pressure vessel or boiler is placed in service, it is no longer under the original construction code rules. Actually, as soon as the Manufacturer’s Data Report is signed by the Authorized Inspector (AI), the vessel is no longer under the rule of the ASME. It is still a "Code" vessel, welding work just now falls under other codes. Even if the vessel is still at the fabrication shop, any welding performed on the vessel after that time will have to come under other repair codes. And those repair codes are the subject of this text.

The NBIC inspection and repair code governs the repair of pressure vessels and boilers after initial construction. The NBIC repair is followed by the "R" stamp being affixed to the vessel.

The API 510 inspection and repair code governs the repairs of pressure vessel after they have been placed in service.

If a vessel is completed at the shop as defined by the AI signing the Manufacturer’s Data Report and a repair is required there are 2 options for the manufacturer.

Either method is acceptable by all codes and is subject to the approval of the AI and the vessel purchaser.

Frankly, from what I have observed, most shops would just perform the repair and ship the vessel "as is", with or without a new "R" stamp, that just depends on how accessible the AI is and when the vessel is due to the purchaser. Also, many purchasers are not involved with any part of the vessel until it arrives at their facility.

The API 510 code would not be enforceable yet as API 510 is an In-Service Repair Code, and the above vessel is not yet been in service.

The API 510 and NBIC both contain rules for repairs and alterations of pressure vessels. Both Codes require an inspector who has passed an examination to perform inspections and sign off on the work performed. The quality program requirements in both are almost the same and the intent is identical. Under both documents you are required to assure that the work performed results in a vessel which will operate safely for the intended service.

The NBIC requires that the organization performing the repairs hold an "R" Stamp issued by the National Board of Boiler and Pressure Vessel Inspectors and that the work be inspected by an inspector holding a National Board Commission. API 510 allows the Owner/User to choose whatever repair organization it approves (this may be his own maintenance department, an "R" Stamp holder, or a local welding contractor). The API 510 inspector is also required to make the inspections and sign for the repair.

The vessel under repair is still a "Code" vessel as the ASME BPVC applied only to the original construction. Once the vessel is constructed, it is always a "Code" vessel unless the code nameplate is removed.

Will the same quality of work be performed if one uses an API 510 Inspector rather than an AI? Because of the quality control manuals and the responsibilities of the Inspectors, there should be no difference in the quality of work.

However, most things in life depend on the individuals doing the work. So the quality of work under either code depends on the welders, the QA/QC and the Inspectors, not the Codes. This is what I have observed in life and I am confident that you also have had the same experience.

In actual observance of welding performed, I have found that the "R" repair in accordance with the NBIC is typically a poorer repair job than that governed under the API 510. The reason for this is that under the NBIC rules, the only signature that counts is the AI. An often heard comment is "The AI already bought it.", meaning as long as the AI thought it was OK, then that was good enough. The real problem is that the AI generally never reviews the work, welding, MTRs, NDT reports, fit-up, welder certs, etc. He is usually called to witness the hydrotest, and that is about all he does. The difference, in the petrochem industry, is that there is almost always an individual who follows the job from beginning to end. He has a vested interest in the safe and proper repair and construction of the vessel because he works there everyday. This individual is the API 510 inspector. The same rules apply in both codes, so in theory the same work should be performed. However, in practice the work performed in accordance with API 510 is inherently better than that performed under the NBIC rules.

Most states have adopted the NBIC as law and so the NBIC rules must be followed. That does not mean you or your API 510 inspector cannot be involved. If it is your vessel, then you can have the final say, but it still must be accepted by the AI. Some states also allow an API 510 Owner/User program. This allows a pressure vessel owner to inspect and repair pressure vessels in accordance with API 510 and some state rules.

Check with your state or AI to see if your state requires the use of NBIC.