It is good that we are finding fewer and fewer facilities without pressure testing and leak testing records on their process piping. But now comes the difficult question:
Is pressure and leak testing required after maintenance or alterations on piping systems?
So, most companies will have their newly installed piping pressure tested and leak tested by the contractor who performed the installation. But two months into operating said piping, some maintenance work is necessary and this work will require us to OPEN the piping system, make repairs, and then return the piping to service. How many of you will include some type of integrity testing on this circuit of piping that has been opened/altered/repaired BEFORE we return it to service?
Using my favorite Piping Maintenance RAGAGEP, API 570, we can see that…
(emphasis by me)
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8.2.8 Pressure Testing After welding is completed, a pressure test in accordance with 5.11 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 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 ºF (260 ºC); and 2) socket-welded fittings for sizes NPS 2 or less and design cases up to 500 ºF (260 ºC). 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 831.3 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. |