If API 570 is your facility’s piping inspection/repair RAGAGEP, the battle over “repair requirements” just got easier! A very popular question in PSM/RMP circles has become…
“Do we have to make repairs in the same manner as we did the initial install of the pipe?”
In other words, what is being asked is…
“Can we bypass some of the ASME B31 requirements like using coded welder or pressure test or leak test when I have to make repairs to the piping?”
Of course, the best answer is NO, you must treat the repairs as cautiously as the original install and meet all the requirements that were intended to be met when the pipe was installed. This means that ASME B31 requirements are the same for a repair as they were when we installed it. But this kind of language is not crystal clear in ASME B31 because the series of codes is for NEW CONSTRUCTION/INSTALLATIONS – not alterations or repairs. So engineers, and those who mascarade as engineers have always liked to play the “show me in the standard/code” game when Process Safety Engineers required the same requirements for alterations/repairs as we did when the pipe was first installed/constructed. But now API 570 makes our position crystal clear!
Section 8 – 8 Repairs, Alterations, and Rerating of Piping Systems contains requirements for welders, documentation, examination, and yes PRESSURE TESTING the repairs BEFORE the piping is returned to service.
(emphasis by me)
8.1.1 General
The principles of ASME B31.3 or the code to which the piping system was built shall be followed to the extent practical for in-service repairs. ASME B31.3 is written for the design and construction of piping systems. However, most of the technical requirements on design, welding, examination, and materials also can be applied in the inspection, rerating, repair, and alteration of operating piping systems. When ASME B31.3 cannot be followed because of its new construction coverage (such as revised or new material specifications, inspection requirements, certain heat treatments, and pressure tests), the piping engineer or inspector shall be guided by API 570 in lieu of strict conformity to ASME B31.3. As an example of intent, the phrase “principles of ASME B31.3” has been employed in API 570, rather than “in accordance with ASME B31.3.” The principles and practices of API 577 shall also be followed for all welded repairs and modifications.
8.1.2 Authorization
All repair and alteration work shall be done by a repair organization as defined in Section 3 and shall be AUTHORIZED by the inspector PRIOR to its commencement. Authorization for alteration work to a piping system may NOT be given without prior consultation with, and approval by, the piping engineer. The inspector will designate any inspection hold points required during the repair or alteration sequence. The inspector may give prior general authorization for limited or routine repairs and procedures, provided the inspector is satisfied with the competency of the repair organization.
8.1.3 Approval
All proposed methods of design, execution, materials, welding procedures, examination, and testing shall be approved by the inspector or by the piping engineer, as appropriate. Owner/user approval of on-stream welding is required. Welding repairs of cracks that occurred in-service should NOT be attempted without prior consultation with the piping engineer in order to identify and correct the cause of the cracking. Examples are cracks suspected of being caused by vibration, thermal cycling, thermal expansion problems, and environmental cracking. The inspector shall approve all repair and alteration work at designated hold points and after the repairs and alterations have been satisfactorily completed in accordance with the requirements of API 570.
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8.2.2 Procedures, Qualifications, and Records
The repair organization shall use welders and welding procedures qualified in accordance with ASME B31.3 or the code to which the piping was built. See API 577 for guidance on welding procedures and qualifications. The repair organization shall maintain records of welding procedures and welder performance qualifications. These records shall be available to the inspector PRIOR to the start of welding.
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8.2.7 NDE
Acceptance of a welded repair or alteration shall include NDE in accordance with the applicable code and the owner/user’s specification, unless otherwise specified in API 570. The principles and practices of API 577 shall also be followed. When surface and volumetric examinations are required, they shall be in accordance with ASME BPVC Section V (or equivalent).
8.2.8 Pressure Testing
After welding is completed, a pressure test in accordance with 5.8 shall be performed if practical and deemed necessary by the inspector. Pressure tests ARE NORMALLY REQUIRED after alterations and major repairs. See ASME PCC-2, Article 5.1 (Pressure and Tightness Testing of Piping and Equipment) for more information on conducting pressure tests. When a pressure test is not necessary or practical, NDE shall be utilized in lieu of a pressure test. Substituting appropriate NDE procedures for a pressure test after an alteration, re-rating, or repair may be done ONLY AFTER consultation with the inspector and the piping engineer.
For existing insulated lines that are being pressure tested after repairs, re-rating, or alterations, it is not necessary to strip insulation on all existing welds. Pressure tests with longer hold times AND observations of pressure gauges can be substituted for insulation stripping when the risks associated with leak under the insulation are acceptable.
When it is not practical to perform a pressure test of a final closure weld that joins a new or replacement section of piping to an existing system, ALL of the following requirements shall be satisfied.
a) The new or replacement piping section is PRESSURE TESTED AND EXAMINED in accordance with the applicable code governing the design of the piping system, or if not practical, welds are examined with appropriate NDE, as specified by the authorized piping inspector.
b) The closure weld is a weld between any pipe or standard piping component of equal diameter and thickness, axially aligned (not miter cut), and of equivalent materials. Where slip-on flanges or socket weld fittings are permitted by the specification for the piping system, they may be used within the limitations of that specification.
Acceptable alternatives are:
1) slip-on flanges for design cases up to Class 150 and 500°F (260°C); and
2) socket-welded fittings for sizes NPS 2 or less and design cases up to 500°F (260°C). A spacer designed for socket welding or some other means shall be used to establish a minimum 1/16 in. (1.6 mm) gap. Socket welds shall be per ASME B31.3 and shall be a minimum of two passes.
c) Any final closure butt weld shall be of 100% RT; or angle beam ultrasonic flaw detection may be used, provided the appropriate acceptance criteria have been established. d) MT or PT shall be performed on the root pass and the completed weld for butt welds and on the completed weld for fillet welds.